Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ Past and Future _ Mars Sample Return

Posted by: Rakhir Apr 7 2006, 07:32 AM

Next phase reached in definition of Mars Sample Return mission

http://www.esa.int/esaCP/SEMJAGNFGLE_index_0.html

Posted by: RNeuhaus Sep 5 2006, 04:50 PM

A very good article :http://www.spacedaily.com/reports/Returning_To_Sample_Mars_999.html

In resume: This mission must be of international cooperation.

Rodolfo

Posted by: ljk4-1 Sep 21 2006, 05:08 PM

Sample return has been highlighted as a key priority for future planetary missions in discussion meetings held at the first European Planetary Science Congress in Berlin.

http://www.europlanet-eu.org/index.php?option=com_content&task=view&id=76&Itemid=32

Prof. Bernard Foing, Project Scientist for the SMART-1 mission, said, “Europe has now looked at the Moon, Mars and Venus and we have put our finger on Titan. These are great achievements. But for the future, it is not enough to briefly ‘kiss’ the surface of other solar system objects. We must bring them back to Earth for analysis.”

Posted by: climber Sep 21 2006, 05:30 PM

Isn't it a coïncidence! Mark Adler is talking about his own experience on the subject on TPS blog today and tomorrow here : http://www.planetary.org/blog/article/00000701/ smile.gif

Posted by: spdf Oct 13 2006, 09:51 AM

Funding a Mars sample return mission is not a good idea. This is a very expensive and complex mission. However since the ways to test space technologies on Earth are limited the possibilities are quite high that a Mars sample return cannot be achieved on the first try. Thats the way it is. But I don t think because of the high cost the public and many "space enthusiast" will have tolerance for a failure on the first try. The political climate is simply not right for high risk missions. So imagine the bashing after ... .

Posted by: climber Oct 13 2006, 12:23 PM

QUOTE (spdf @ Oct 13 2006, 11:51 AM) *
Funding a Mars sample return mission is not a good idea. This is a very expensive and complex mission. However since the ways to test space technologies on Earth are limited the possibilities are quite high that a Mars sample return cannot be achieved on the first try. Thats the way it is. But I don t think because of the high cost the public and many "space enthusiast" will have tolerance for a failure on the first try. The political climate is simply not right for high risk missions. So imagine the bashing after ... .

If you read what Mark Adler says, he doesn't foresee a MSR before well, 20-30 more years. World will be different then...

Posted by: RNeuhaus Oct 13 2006, 07:14 PM

First watch how the russians will be doing by returning the Mars' moon samples with the Phobuss-Grunt spacecraft. Phobus-Grunt is scheduled for launch in 2009. This is indeed cheaper than landing on Mars.

In order to go on on the MRS project be feasible that the man feel highly confident for the success of the project. I think, up to know, we are still close and need about 5-10 years more in order to improve the technology and also to collect money and support from many nations. Up to now, not only russians are doing it but also along with ESA and China.

More details, visit on http://www.unmannedspaceflight.com/index.php?act=ST&f=9&t=1844

Rodolfo

Posted by: Zvezdichko Jan 22 2007, 03:53 PM

QUOTE (RNeuhaus @ Oct 13 2006, 07:14 PM) *
First watch how the russians will be doing by returning the Mars' moon samples with the Phobuss-Grunt spacecraft. Phobus-Grunt is scheduled for launch in 2009. This is indeed cheaper than landing on Mars.

In order to go on on the MRS project be feasible that the man feel highly confident for the success of the project. I think, up to know, we are still close and need about 5-10 years more in order to improve the technology and also to collect money and support from many nations. Up to now, not only russians are doing it but also along with ESA and China.

More details, visit on http://www.unmannedspaceflight.com/index.php?act=ST&f=9&t=1844

Rodolfo


I'm actually quite pessimistic about the Russian Phobos-grunt sampling attempt. Of course, a lot of things have changed since the previous failures, but ... the mission is very ambitious for the current financial state of Roscosmos. Russia hasn't returned samples for more than 30 years ( the Moon ), and the last partially successful mission to Mars was 20 years ago. A Phobos sampling mission requires still untested technologies - Phobos lander, Phobos ascend vehicle. The return capsule will be quite different than these used in the 70s.
And yet, this attempt is worth trying.

Posted by: PhilHorzempa Jul 2 2007, 08:07 PM

Recent written comments by Alan Stern indicate that he wants to initiate MSR, Mars
Sample Return, in the near future, perhaps in FY2008.

Also, the National Academy of Sciences now recommends a new approach to MSR.
Instead of one Grand mission, it should be spread out over several years. It suggests
that all future Mars rovers be equipped with a sample caching system. After several
missions, NASA/ESA would decide whcih site held the best samples, and a retrieval system
would be sent. Once the samples were launched into Martian orbit, they could linger there
until an orbital rendezvous vehicle was sent. This would spread the risk and cost over
several years, instead of gambling everything in one Battlestar Galactica mission.

The recent Orbital Express mission has been a pathfinder for an unmanned rendezvous
and docking craft that would be an important part of MSR. However, it's mission is ending
before NASA has a chance to fully utilize it. See the article on this link -

http://www.space.com/missionlaunches/070630_orbital_express.html




Another Phil


Here is a view from Orbital Express. Imagine that someday, someday this will
be the view from Martian orbit as the Mars Ascent Vehicle closes in for docking with
the Earth Return Vehicle. The background view will be slightly different. We will see
the Martian deserts below, but only empty river channels and rift valleys.






Go to

http://www.darpa.mil/orbitalexpress/mission_updates.html


for more photos.

Posted by: hendric Jul 2 2007, 08:40 PM

On the surface that sounds like a good idea, only sending the "retrieval system" to the interesting caches, but I think that would end up being just as complicated as the BSG style missions. The retrieval system would end up requiring rover-like mobility, since it has to reach the cache in the previous mission. It could probably forgo most instruments, but it would still be a large, precision landed rover. It makes more sense to develop a sample return canister/rocket to be taken on each Mars mission, with the rendevous occuring in space instead of on the ground. The space retrieval bus could even collect multiple canisters before returning home.

Posted by: Analyst Jul 3 2007, 09:15 AM

QUOTE (hendric @ Jul 2 2007, 08:40 PM) *
It makes more sense to develop a sample return canister/rocket to be taken on each Mars mission, with the rendevous occuring in space instead of on the ground. The space retrieval bus could even collect multiple canisters before returning home.


The return capsule/rocket and "launch pad" is very massive. There is no chance to have every rover carry one. We are talking about several hundreds of kilogramms minimum.

The missions can be spread as described above: (1) landers/rovers to select samples, (2) extra lander to carry sample into orbit and (3) orbiter to escape Mars and return to earth. I strongly doubt this will be more efficient than one single MSR mission. Its hard to integrate, several launches, even more things can fail etc. In the end you need all the same elements. I doubt this will be more cost effective. MSR is a classic flagship mission like Viking or Cassini. I don't see a clever way to change this.

Analyst

Posted by: dvandorn Jul 3 2007, 03:11 PM

It all comes down to what you really want out of an MSR mission. Remember, Mars is a fairly big planet as far as rocky planets go. It has a significant gravity well which requires a lot more energy to escape than, say, Luna requires. It also has an atmosphere that gets annoyingly in the way as you try and leave, requiring more energy to achieve orbit from the surface than an airless body would.

So, sending a sample off the surface and back into Mars orbit is not an insignificant operation; it takes more fuel than you'd think. If you include the fuel needed to inject the sample into a trans-Earth trajectory, as well as the heat shielding needed to get it back to Earth intact, you're landing an awful lot of mass on Mars that is dedicated to the return-to-Earth systems. (I'm trying to get y'all used to the idea that an MSR return-to-earth stage on a lander is going to need to be a *lot* bigger, beefier and energetic than, say, the upper stage used by the Russian Luna sample return landers. It's not the "model rocket on a Viking" setup some artists have imagined, it's more like landing a Thor or a Delta on Mars and having it ready to launch with no ground support equipment beyond that you bring with you.)

It would take an Ares V to get such a lander onto Mars with the ability to return more than a few grams of soil and rocks. Such a lander would be so heavy with just the fuel and other things needed to get your sample back to Earth that you'd have no mass left for roving to look for and pick up good samples, much less for a comprehensive survey sensor package.

So, even though it requires three separate launches and spacecraft busses, the concept of splitting the mission into three major pieces -- the survey spacecraft, the surface launch spacecraft and the return-to-Earth spacecraft -- lets you distribute the weight required into pieces that don't all have to be landed and don't all have to support Earth return. Remember, the same booster can get kilograms into Mars orbit that can only get grams onto the surface.

So -- if you want a single scoop of Martian soil, a sample that weighs no more than two or three kilograms, then a single spacercaft architecture is usable. If you want to return tens of kilograms of samples, and not just whatever a scoop can pick up from off the side of the lander deck, you're actually better off with the three-spacecraft architecture. Until and unless we make some propulsion system breakthroughs, it's just not energy-economical to do it with the single spacecraft concept -- not to get enough of a sample back to make the mission worthwhile, anyway.

-the other Doug

Posted by: helvick Jul 3 2007, 08:35 PM

I don't think it can be done easily but I don't think the mass penalty is quite that bad. My back of the envelope scratchings based on some Delta-V and typical Isp's from http://www.pma.caltech.edu/%7Echirata/deltav.html

Martian Surface to LMO ~ 4.1 km/sec
Mars LMO to Earth C3 orbit ~ 2.9 km/sec
Total ~7km/sec Delta-V.

To get a 1 kg sample of mars dirt to Earth C3 orbit.
Assume we have motors with an Isp of about 280 (like ammonium perchlorate solids)
Two stages:
(1) LMO Stage - Motor, shell and supports for the mars launch first stage weigh ~ 5kg
First stage then needs ~ 37kg of fuel to get 11kg to LMO ( its own 5kg dry weight plus 6kg for the initial mass of the Earth Transfer Stage)
(2) Earth Transfer stage weighing 2kg dry (container+2nd stage motor+1kg payload+beacon)
Requires 4kg of fuel to produce +-3.1 km/sec Delta-V
Total initial mass = 48kg.

Alternatively.
Single Stage to LMO
Mars Surface to a Mars orbit stable over a couple of years. Say we need 4.4km/sec Delta-V (LMO + some margin) and the dry weight including payload we are working with is ~ 6kg.
Total initial mass = 29kg.

There's lots of holes in these of course (launch stage drag, no earth capture component ... ) but I reckon you can get 0.5-1kg of sample back for <100kg of landed mass. That's not possible today of course but it isn't warp drive level science fiction either.

That said we are limited today to landing something less than a ton or so onto the Martian surface even with the biggest launch vehicles so without something comparable to the Ares V no-one is ever going to return more than a kilo or two.

Posted by: antipode Jul 3 2007, 11:21 PM

Drifting a bit OT here, but its obvious to all that MSR will be:

1) VERY expensive
2) Technically risky
3) Possibly providing limited 'bang for the buck' even if it succeeds

Might sample return better be conducted as part of a MANNED precursor mission - one that simply orbits Mars Apollo 8 style (plus visits to Phobos etc). Small surface probes/rovers could then be dispatched from orbit, controlled in near real time etc etc. I know such missions have been proposed, and I'm aware of the objections to them, but MSR is one of those missions that, like controlled fusion, is so hard and so expensive that its always 20-30 years in the future.

P

Posted by: Phil Stooke Jul 4 2007, 12:22 AM

Antipode, funny you should mention that, as I am now writing up a description of a mission which includes some elements of what you describe. More on this later.

Phil

Posted by: nprev Jul 4 2007, 05:51 AM

Sounds like one of the old Soviet manned Mars mission proposals, IIRC.

Posted by: dvandorn Jul 4 2007, 04:24 PM

Such a mission has a lot to be said for it. For one thing, it's easier to send a lot of lab equipment to, say, Phobos than to the surface of Mars, and it's likely cheaper (in terms of energy) to get the mass of the equipment you want to use to study Mars rocks to Phobos than it is to bring the rocks all the way back to Earth.

So, you set up a manned microgravity habitat on/in Phobos, outfit it with the best analysis tools you can easily get out there, and send down small sample return probes that bring you up a few kg of carefully selected rocks and soils every few months. Your PIs live on Phobos and send the detailed data back to colleagues on Earth.

What would be the minimum lab requirements for a Phobos geological analysis base? You'd want to have fine-scale composition and isotope analysis, as well as the best rock dating equipment you can afford to transport. You'd also want equipment for examining micro-fossils (just in case) and for examining ices and such for possible biological activity or remnants.

What suite of instruments would best serve your purposes in such a set-up? What are their power requirements? And how much of it can be feasibly transported via rocket from Earth to Phobos? Those are the questions I'd be asking right now...

-the other Doug

Posted by: helvick Jul 4 2007, 05:32 PM

One fairly big problem that I see with the idea though is that the stuff that you loft up from the Martian surface would also have to land on Phobos and do so incredibly precisely and without damaging your lab. That's pretty hard if you ask me - It seems to me that it would be a lot easier to send stuff all the way back to Earth. The Delta-V difference between "Mars-Surface to landed on Phobos" and "Mars-Surface to Earth C3=0 orbit" is only 1.5km/sec.

Posted by: tty Jul 5 2007, 02:11 PM

QUOTE (dvandorn @ Jul 4 2007, 06:24 PM) *
So, you set up a manned microgravity habitat on/in Phobos, outfit it with the best analysis tools you can easily get out there, and send down small sample return probes that bring you up a few kg of carefully selected rocks and soils every few months. Your PIs live on Phobos and send the detailed data back to colleagues on Earth.


It seems to me that the most efficient way to use a manned outpost on Phobos would be to search for bits and pieces of Martian rock on Phobos itself. Nearly every large impact on Mars must have caused some debris to end up on Phobos. You could do the preliminary selection and analysis on Phobos and send the most interesting bits back to Earth for detailed study. In this way it should be possible to get at least a rough outline of Martian historical geology and also "ground truth" data to interpret orbital imagery.

Another fairly simple and cheap, though very limited form of sample return would be to expose a Stardust-type collector during aerobraking and returning it using a small Earth-return stage.

Posted by: gpurcell Jul 5 2007, 02:57 PM

QUOTE (tty @ Jul 5 2007, 02:11 PM) *
Another fairly simple and cheap, though very limited form of sample return would be to expose a Stardust-type collector during aerobraking and returning it using a small Earth-return stage.


SCIM has been proposed in the last two Scout competitions and would follow that mission profile.

Posted by: mchan Jul 5 2007, 11:13 PM

QUOTE (dvandorn @ Jul 4 2007, 09:24 AM) *
Such a mission has a lot to be said for it. For one thing, it's easier to send a lot of lab equipment to, say, Phobos than to the surface of Mars, and it's likely cheaper (in terms of energy) to get the mass of the equipment you want to use to study Mars rocks to Phobos than it is to bring the rocks all the way back to Earth.

So, you set up a manned microgravity habitat on/in Phobos, outfit it with the best analysis tools you can easily get out there, and send down small sample return probes that bring you up a few kg of carefully selected rocks and soils every few months. Your PIs live on Phobos and send the detailed data back to colleagues on Earth.

Would it be cheaper to bring the rocks or the PIs back to Earth? The PIs are coming back, right? unsure.gif

Posted by: dvandorn Jul 6 2007, 03:54 AM

Well, it depends... the PIs have to get their results published before they can come home, after all... wink.gif

-the other Doug

Posted by: centsworth_II Jul 6 2007, 05:27 AM

Publish or perish? ohmy.gif

Posted by: dvandorn Jul 6 2007, 06:06 AM

Literally!

-the other Doug

Posted by: lyford Jul 6 2007, 03:23 PM

biggrin.gif biggrin.gif biggrin.gif

Posted by: AlexBlackwell Jul 6 2007, 11:40 PM

http://www.aviationweek.com/aw/generic/story.jsp?id=news/mars070607.xml&headline=Mars%20Mission%20May%20Be%20Moved%20Up%20&channel=space
By Frank Morring, Jr.
Aerospace Daily & Defense Report
July 6, 2007

Posted by: ustrax Jul 26 2007, 10:44 AM

Didn't know where to put this...

http://www.space.com/scienceastronomy/070726_mars_samplereturn.html

This is how I like to hear them talking! biggrin.gif

Posted by: gndonald Jul 26 2007, 12:17 PM

QUOTE (Phil Stooke @ Jul 4 2007, 08:22 AM) *
Antipode, funny you should mention that, as I am now writing up a description of a mission which includes some elements of what you describe. More on this later.

Phil


Was this by any chance the 'Mars Twilight Flyby' that NASA was planning in 1966?

As I remember the documents I looked through the plan was to fly past Mars, drop off six probes (1 orbiters, 3 hard landers & 2 soft landers), one of which would rocket into orbit a capsule containing a Mars rock/atmosphere sample and film from a high resolution camera for pickup by the manned flyby craft.

On the way back the astronauts would analyze the surface samples and beam the results back to Earth.

Posted by: Phil Stooke Jul 26 2007, 06:07 PM

gndonald:

"Was this by any chance the 'Mars Twilight Flyby' that NASA was planning in 1966? "

No. It's about Phobos, and has evolved into my abstract for the Phobos conference.

Phil

Posted by: JRehling Jul 26 2007, 08:56 PM

[...]

Posted by: nprev Jul 26 2007, 09:26 PM

I get your point, JR. In all fairness, though, there does seem to be some precedent for the strategy. Ranger/LO/Surveyor were all precursors to Apollo, so since Mars is the espoused future goal for US manned exploration it's getting the lion's share of UMSF attention.

Not necessarily saying it's the right way to go, but merely speculating on the apparent reason for the focus.

Posted by: Pavel Jul 26 2007, 09:42 PM

I think you missed the "far into the future" part. Mars sample return is going to be harder than the current missions, and it's likely to take a lot of time. And it can fail like any other mission, for technical or monetary reasons. We can get into the situation when specialists are waiting for additional financing, and there are no working rovers on Mars. The sample return mission is just too big for the pipeline now.
A think we need an "entry" strategy - how to implement ambitious missions efficiently, so that we don't end up with another over-expensive and unsustainable Apollo-like program.

Posted by: JRehling Jul 27 2007, 09:01 PM

[...]

Posted by: Pavel Jul 27 2007, 10:26 PM

Mars is also special because it the easiest extraterrestrial planet to research. Try getting samples from Mercury or Venus. Now that would be hard!

The Moon and asteroids are easier, but some questions can only be answered by researching planets. Mars is a natural stepping stone for planetary research. We may learn enough about Mars at some point, but the technology developed for Mars will be reused for other celestial bodies.

A massive one-off project would be less useful for further exploration than smaller specialized missions. MER-like robots can be driving on Europa one day.

Posted by: Jim from NSF.com Jul 29 2007, 02:42 PM

QUOTE (JRehling @ Jul 27 2007, 05:01 PM) *
I don't think we want a sustainable program. Not a sustainable big program. That implies money pit to me.

The people doing research on liver cancer don't want a sustainable liver cancer research program. They want to cure liver cancer. Research is the means, not the end. I personally would like to see research on liver cancer end -- once they cure liver cancer.

excess quoting removed



Nonsense.
Liver cancer will continue after one cure has been found. The cure may be expensive, lengthy etc
We know how to set broken bones yet research continues and better "cures" are the outcome

Has ocean research finished.

Not until there is a human presence on Mars, will the missions end. Strike that, there may be Martian weathersats.

Posted by: spdf Aug 1 2007, 03:55 AM

A question here: If you have a ~30-40 kg small satellite and you want to launch it from mars surface into mars leo, how much energy do you need for it? And how big would be the rocket? Is there any more detailed study on this online?

Thanks

Posted by: ElkGroveDan Aug 1 2007, 04:16 AM

QUOTE (spdf @ Jul 31 2007, 07:55 PM) *
A question here: If you have a ~30-40 kg small satellite and you want to launch it from mars surface into mars leo,

not sure, but I think you'd first want to launch it in lmo wink.gif

Posted by: helvick Aug 1 2007, 06:40 AM

You can find some of my back of the envelope calculations on that question in an early post in this thread ( http://www.unmannedspaceflight.com/index.php?showtopic=2570&st=0&p=94079&#entry94079 )
The delta-v that you need is 4.1km/sec to from the martian surface to LMO. Assuming you're using an engine with performance similar to an ammonium perchlorate solid motor (ie an Isp of around 280), then you will need at least 135kg of fuel. You will need an actual launch shell to put it all in which would add another 10-20kg + another 30-60kg of fuel to cope with that extra initial mass.
Note I've made no allowances for atmospheric mass here and that will be significant even though the martian atmosphere is not very dense.
Excluding drag you are talking about an initial mass of at least 215kg to get 40kg to LMO.

And finally you need a (martian) ground assembly to hold it all before launch and I've no idea how to estimate how massive that might be.

Posted by: nprev Aug 5 2007, 01:45 AM

QUOTE (helvick @ Jul 31 2007, 11:40 PM) *
And finally you need a (martian) ground assembly to hold it all before launch and I've no idea how to estimate how massive that might be.


I would assume that the return stage would be integrally mounted to the descent stage in the proper configuration--pointy end up, propellant loaded-- before Earth departure; physically configuring it for launch on Mars in any significant way seems really risky from a technical standpoint. Still, lots of mechanical complexity needed to put the payload aboard, unless it's a simple scoop...

Posted by: JRehling Aug 9 2007, 04:37 AM

[...]

Posted by: monitorlizard Aug 17 2007, 08:01 AM

I'm probably going to get my head handed to me for saying this, but can't a case be made for a Mars sample return with a direct Mars to Earth trajectory, bypassing a rendezvous in Mars orbit with an Earth return stage?

The obvious counter to this idea is that the size/weight of the Earth return rocket on Mars would be MUCH larger than that needed to reach low Mars orbit. OK, agreed. But there are a lot of advantages to direct to Earth launchings from Mars. One: A Mars orbiter to receive the sample canister wouldn't be needed. That eliminates an entire launch from earth and an entire spacecraft. Two: No need for a rendezvous in Mars orbit. This is an extremely complex operation to do unmanned, and I think it is the pacing technology for when a sample return could be done. It also raises the cost of the mission enormously.

The alternative is to launch a single massive spacecraft to Mars, have it collect and store samples by whatever means is preferred, wait until the next alignment of earth and Mars, then launch the sample return spacecraft directly to earth (no orbiting Mars first). This would require the use of a much larger launch vehicle from Earth than a standard sample return scenario, but that cost would be offset by requiring no Mars orbiter launch, and the much greater simplicity of the Mars to earth portion of the mission (which should also reduce costs greatly and, more importantly, give a greater chance of success).

I've made my case, let the carnage begin. biggrin.gif

Posted by: djellison Aug 17 2007, 08:29 AM

Well - yes - carnage indeed. Instead of a 5kg litle satellite to launch from the surface - you have to land, and then launch again - a much larger launch vehicle, to launch not only the small sample cache but also a complete, fueled, spacecraft and entry capsule - able to not only enter the Earth's atmosphere at the other end - but navigate with TCM's between Mars and Earth. A full up proper spacecraft - perhaps 100kg (complete guess). Landing and then launching your return capsule is not easier.

You're making the requirements of the MAV an order of magnitude larger - and thus the landing requirements an order of mag larger (when we don't know how to land >750kg on the surface) and thus the first launch vehicle from Earth being an order of magnitude larger....which doesn't really exist

I think from a biohaz perspective (even if it's just paranoia) - taking a small cache from orbit, putting it into another large entry capsule that is then sealed makes a lot of sense. If you have the entry capsule on the surface, you've exposed it to the Martian environment as well.

I can perhaps see the case for single launch - a viking like split between lander and orbiter, and then then a re-rendezvous on orbit for the return to Earth - but taking EVERYTHING you need to get from Mars back to Earth ( a complete spacecraft) all the way to the surface and back makes the entire problem much more difficult than it needs to be. Also- orbit rendezvous and return offers the option for multiple samples collected and launched from multiple sites to be returned via a single orbiter.

Posted by: monitorlizard Aug 17 2007, 09:03 AM

Thanks, Doug. I knew I was going to be defeated on this, but reading the details answered a lot of questions I had.

Posted by: djellison Aug 17 2007, 09:11 AM

It's not 'defeated' - I mean, there's merit to making as few manouvers in the system as possible. If you could make a spacecraft with the necessary Delta V and entry ability to do the Mars to Earth flight - but <10kg - perhaps it could be done - but I'd want my return vehicle to be very big, very reliable, and packed full of redundent systems.

Doug

Posted by: Cugel Aug 17 2007, 09:27 AM

Of course the points Doug mentions are valid and pretty serious drawbacks for the Direct-to-Earth approach.
However, there is (at least) one point in favor for it: ISRU, aka the Zubrin Fuel Processor.
By far the greatest part of the mass of the return vehicle must be fuel, so if you can somehow land with empty tanks and then do a refill the whole plan makes more sense. You probably can't do DTE without ISRU. But even in a split mission approach ISRU could perhaps be an interesting option.

There is also another issue with the split mission architecture. Is it really possible to automatically rendezvous with a completely passive cannister? Something that doesn't have a radio, position control, an energy source, etc... How do you know its orbit with enough accuracy? But if it can't be a passive cannister, how much hardware must be added before you can find it in orbit? What does that do to that 5 Kg mass number?
Actually, I don't believe in such small numbers, it will probably be more like 100 Kg. At least.

Posted by: djellison Aug 17 2007, 09:36 AM

I think a sample cache cannister would have a small battery and a beacon radio.. It'd be interesting to know how much intelligence was required on the 'dumb' part of the recent DARPA orbit rendezvous demos when doing the automated undocking and redocking.

Here's a thought. You could make your sample cache a derivative of a cube sat.

Doug

Posted by: Cugel Aug 17 2007, 02:05 PM

A cube-sat? Hmmm, I believe at Delft University (Holland) they actually are developing something like that called a nano-sat. As I recall it was 30 cm. (12 inch) on each side, or something. (And it carried a radio) I will see if I can find some more information on it.

Posted by: djellison Aug 17 2007, 02:28 PM

Cubesats are a well established and popular platform ( you'll even find extensive info about them here )

It's 10 x 10 x 10 cm and no more than 1kg

You can extend the platform into a double or triple cubesat ( 10 x 10 x 20 and 10 x 10 x 30 , 2 and 3kg respectively) for added performance.

Doug

Posted by: Cugel Aug 18 2007, 01:08 PM

So I guess the 'cannister' could look something like the http://www.delfic3.nl/index.php?option=com_content&task=view&id=67&Itemid=109

This one doesn't have active attitude control, but that's basically all it's missing for being a perfect MSR cannister. Work is also being done to develop autonomous rendezvous, where nanosats would catch up with big satellites for maintenance or repair. This cube-sat development could really be extremely useful for MSR architectures!

So, I'm willing to lower my bid to 10 Kg! rolleyes.gif
2 Kg of samples.
5 Kg for the standard cubesat bus
3 Kg for attitude control, thrusters and a docking mechanism.

Posted by: nprev Aug 19 2007, 04:09 AM

This may be WAY off base, but has anyone considered a purely ballistic MSR mission profile?

What I'm thinking of here is a single-stage (or two at the most, if the upper stage has robust thrusters & agile nav capability) DTE reentry vehicle from the surface of Mars...minimal course correction requirements, tight launch window, maybe even solid-fueled at least for the initial boost phase. Advantages: Relatively simple G&C. Disadvantages: (1) very tight launch window, (2) probably high velocity wrt Earth for entry phase. Don't know without a formal risk analysis how these very coarse factors would play out, nor whatever other dragons there may be.

(BTW, thinking of grams, not kilograms, in terms of sample return quantities: even a very little bit of Mars would go a long. long way in terms of answering fundamental/nagging questions such as the presence or absence of superoxides, carbon abundance/source, iridium ratios, etc., etc., ...)

Posted by: The Messenger Aug 19 2007, 05:37 AM

Good question. Solid fuels have a great track record in space...I think there has been one possible failure in 300+solid propellant motor ignitions in the vacuum of space.

Posted by: tty Aug 19 2007, 07:01 PM

QUOTE (The Messenger @ Aug 19 2007, 07:37 AM) *
Solid fuels have a great track record in space...I think there has been one possible failure in 300+solid propellant motor ignitions in the vacuum of space.


I gather you aren't including the spin/despin rockets of the early Corona recce satellites which went bang in a disconcerting number of cases.

Posted by: djellison Aug 19 2007, 07:48 PM

Or the CONTOUR kick stage smile.gif

Doug

Posted by: Jim from NSF.com Aug 20 2007, 11:36 AM

Or the two HS-376's on PAM's of STS 41-B

Or the IUS on STS-6

Posted by: nprev Aug 21 2007, 02:52 AM

Hmm. Doug & Jim, if you had to shoot from the hip, would you favor liquid or solid propellant for an MSR return vehicle? Expanding on that, do you think that a DTE strategy would be better than, say, a Mars orbit rendezvous with a return vehicle? Seems as if there might be some significant risk analyses needed to make the best possible decision, but interested in your thoughts.

Posted by: John Whitehead Sep 19 2007, 12:07 AM

Here are some comments about "how to get off of Mars" for an affordable sample return mission. We really are talking about a miniature launch vehicle. Mars ascent is far more difficult than any rocket maneuver ever done except earth launch, while Mars ascent needs to be done with about one thousandth the mass of earth launch vehicles.

A Mars ascent vehicle needs to be about 75 percent propellant, e.g. 4200 m/s at 310 seconds Isp. If the rocket stage without payload is 80 percent propellant, then the whole vehicle has to weigh 16 times the payload (12 parts propellant, 3 parts stage hardware, and 1 part payload has the 75% and 80% ratios). If the rocket stage can be as good as 90 percent propellant, then the whole vehicle weighs only 6 times the payload (4.5 parts propellant, 0.5 parts stage hardware, 1 part payload). Much better.

For example, a 20 kg Mars ascent payload means that 80-percent rocket stage technology results in 320 kg launching off Mars, while 90-percent technology needs only 120 kg. That's likely the difference between "not possible" and "possible," given forseeable sizes for Mars landers. I believe the latter can actually be done, if the avionics and batteries can be squeezed into the 20-kg payload allocation -- the rocket engineer perspective on what constitutes payload smile.gif .

So the scale (and therefore cost) of the entire Mars sample return mission depends very strongly on the relative masses of propellant and stage hardware, which in turn is limited by the strength of metal and the difficulty of miniaturization. Whole stages of earth launch vehicles are 90 percent, but there is no precedent for achieving such high numbers in the 1-ton range, let alone on a 100-kg scale. While the above analysis assumes one stage, and multiple stages make it easier in theory, the miniaturization challenge is even more difficult for an upper stage.

Existing flight-qualified solid rocket motors on the scale of interest (~100 kg) are about 90 percent propellant, so it is very tempting to think the problem is solved. However, it is necessary to add directional control. The extra parts could easily over-burden a Mars ascent vehicle. A useful technology development effort might be to build and test-fly a series of small solid rocket stages, all the while working to reduce the auxiliary weight.

For liquid propellants, entirely new custom hardware would have to be developed, because liquid propulsion parts used on satellites and spacecraft are too large and heavy. One possibility for reducing hardware weight is to use a pump-fed engine like launch vehicles do. The principle is to reduce tank weight by making the walls thinner (low pressure), while making the engine more compact (and less massive) by running it at high pressure.

The organizations that build spacecraft propulsion systems have not been asked to design rockets completely from scratch since about 1970 (perhaps a few exceptions), and launch vehicle organizations only build big things. A learning curve should be expected. A bit of good news is that building a Mars ascent vehicle promises to be a very exciting project to inspire the next generation.

John W.

Posted by: monitorlizard Oct 14 2007, 02:15 PM

mepag.jpl.nasa.gov/Announcements/Stern_MEPAG_Summary.pdf

The above has a summary of a meeting between MEPAG scientists and Alan Stern on September 24. It sheds a little new light on Stern's thoughts about an MSR, as well as the MSL descopes, and the 2013 Mars Science Orbiter. He actually makes a 2020 MSR mission seem feasible, even affordable, with the sacrifice of one Mars opportunity mission. Both sides brought out new points I hadn't heard officially before. Worth checking out.

Posted by: John Whitehead Oct 16 2007, 03:25 AM

Thanks to monitorlizard for pointing out the Sep24 MEPAG meeting notes with Alan Stern. To summarize the key points that I noticed regarding MSR:

1. The notion is that skipping one Mars launch opportunity next decade would save enough money to develop and launch MSR in 2020.

2. Planning for science, mission architecture, and curation (sample handling in Houston) are proceeding.

My analysis:

MSR needs two large spacecraft: a lander that carries the Mars Ascent Vehicle (MAV), and an orbiter that carries the Earth Return Vehicle (ERV). Either of these alone is most likely a heavier and more expensive spacecraft than the one single science spacecraft that would be sacrificed in order to pay for MSR. It doesn't appear to compute financially.

Maybe it will be affordable if the 2009 MSL lander works like a charm, and is just copied without new lander development. Then the challenge is back to building a very small MAV, and likely also a new ERV that is small enough to send to Mars orbit in the first place.

All this says that aggressive innovation in down-sizing propulsion technology is needed. Meanwhile, mission architecture studies (number 2 above) can easily have big errors in the estimates of mission mass (and cost) in the absence of the rocket technology.

We have to hope that the science community will appreciate the need for high-risk rocket technology work. There's essentially nothing out there that can be bought and modified or adtapted in order to successfully launch off of Mars.

John W.

Posted by: Jim from NSF.com Oct 16 2007, 11:09 AM

QUOTE (John Whitehead @ Sep 18 2007, 08:07 PM) *
One possibility for reducing hardware weight is to use a pump-fed engine like launch vehicles do.


Not viable. Losses from inefficiencies would be too great. Pressurized systems is the way to go

Posted by: monitorlizard Oct 16 2007, 12:34 PM

"There's essentially nothing out there that can be bought and modified or adapted in order to successfully launch off Mars"

That may very well be true, but there's one possiblity I can think of that might just barely do the job: the ASM-135 ASAT antisatellite weapon that was successfully tested in 1985. It was a two stage (solid propellant?) rocket, with a third stage that I think was just the kinetic warhead itself. The first stage was taken from the Boeing AGM-69 SRAM cruise missile (specifically the Lockheed SR75-LP-1), and the second stage was the Vought Altair III. The third "stage" featured a hydrazine attitude control system to allow a direct hit on the target. Such a control system seems to fit well with the requirements for a rendezvous in Mars orbit with the Earth-return vehicle. (all facts taken from Wikipedia)

The ASAT missile was launched from an F-15 at around 85,000 feet, which is like having an extra stage for your rocket, but I'm wondering if the lower gravity at Mars might make it possible to launch from the surface without an extra stage. The ASAT was described as being able to reach altitudes greater than 350 km (the satellite it hit in 1985 was at 555 km), which seems more than adequate if used at Mars. The weight of the entire ASAT missile was 1180 kg, which seems within the range of possibility for an MSR mission.

I have no idea if such a rocket could actually be used for an MSR, and it might need to be so highly modified that starting from scratch might be better, but I think this is the only already-built system that could meet the weight and performance specs needed. It would be a great sword-to-plowshare moment if it could be used. If MSR is a joint mission with ESA, it could be an ITAR nightmare, but this is supposedly a retired system.

Posted by: monitorlizard Oct 16 2007, 01:07 PM

Rats! I see I'm off by a factor of ten in the weight of the MAV envisioned for an MSR. Pity. I was thinking like a Soviet engineer in the 60s.

Posted by: John Whitehead Oct 16 2007, 11:50 PM

"Jim from NSF.com" noted earlier today that a pump-fed minature launch vehicle may not be viable due to inefficiencies. That's probably true if miniaturization is attempted for centrifugal pumps powered by turbines (aka turbopumps).

Tests on a positive displacement miniature pump indicate that only 2% of the total propellant would provide enough power to run fuel and ox pumps, which is efficient enough. See JPL's Mars Technology Program website for a synopsis at (hope it's still there):
http://marstech.jpl.nasa.gov/content/detail.cfm?Sect=MTP&Cat=base&subCat=LCMT&subSubCat=&TaskID=2289

It's agreed that pressure-fed propulsion is nice and simple and reliable, but you end up having to make tank walls thicker and heavier than you would like them to be, and also engines larger than you would like them to be. For decades, people have envisioned pressure-fed liquid launch vehicles to get off of earth (Bob Truax, "Big Dumb Booster," Beal Aerospace, Microcosm, etc.), but so far none has succeeded. Even using the strongest materials (carbon fiber), the stages end up being closer to 80 percent propellant than 90 percent, and that makes all the difference (in displacing payload with rocket hardware, or in requiring the whole vehicle to grow huge for the same payload).

Regarding monitorlizard's comment about the 1985 ASAT test rocket, the altitude it reached does not necessarily indicate capability to attain orbit (earth or Mars). Reaching orbit requires velocity in addition to altitude. NASA's goal for Mars sample return is to park the sample package in a circular orbit at 500 km altitude. Given only a quarter of orbital energy (half the velocity), it's possible to launch straight up to 500 km (sort of like the ASAT rocket did), but then you fall straight back down again.

"Soviet engineer in the 1960's," is an especially appropriate comparison since their return vehicles that launched off the moon (Luna 16, Luna 20, and Luna 24) weighed about a metric ton. The Mars ascent vehicle has to be a tenth that mass, and just to get to Mars orbit it needs a much higher velocity (4200 m/s) than going from the moon all the way to earth (2800 m/s, which the Soviets did nicely using only one rocket stage).

Great discussion!

John W.

Posted by: nprev Oct 17 2007, 12:16 AM

It seems that for sake of economy and simplicity a solid first stage would be ideal. However, I can't think of anything else but a liquid-fueled (hypogolic?) second stage to achieve orbit; it has to have a throttle & restart capability, esp. if the first stage under- or over-performs, and of course to circularize the orbit. Perhaps pressure-fed tanks controlled by valves alone would overcome the pump problem; pressurize the hell out them with Martian air before launch, then leave the feed pumps on the surface...

Not even touching the autonomous G&C requirements here. This will not be easy.

Posted by: monitorlizard Oct 17 2007, 12:00 PM

I concede now that I was way off with the ASAT idea. It just seems a pity that the Air Force has so many missiles of different sizes and ranges but none seem to be usable as the basis for an MAV.

As long as I'm throwing crazy ideas to the crowd... What if instead of thinking in terms of a 1 kg or larger Mars sample , we go much smaller, say ten grams. Someone has already pointed out here that you could extract a huge amount of science from such a sample size. So you get maybe a small pebble and a little soil. Now the MAV can be smaller, though I admit you still need the same guidance systems, attitude control, radio beacon, etc. (maybe some systems could be made slightly smaller in proportion to the smaller capsule needed for the sample).

Using a balloon to raise an MAV to an altitude of several thousand feet would be a way to make the MAV even smaller, acting as a sort of first stage for the rocket. I don't know how the trade-offs would compare, but if everything were of minimal size, it might be doable. I know it probably seems unnecessarily complex and not worth the effort, yet the U.S. Defence Department studied this very same concept before Sputnik as a way to achieve Earth orbit before the Soviets.
Maybe the fact that they never did it should tell me something.

Posted by: djellison Oct 17 2007, 01:10 PM

QUOTE (monitorlizard @ Oct 17 2007, 01:00 PM) *
Using a balloon to raise an MAV to an altitude of several thousand feet would be a way to make the MAV even smaller,


And also a way to make the MAV far more complex that it ever need be. Balloon's are not great on Mars. The atmosphere is so thin that you would have to have an ENORMOUS balloon to get something like this aloft - and you still have the far from trivial issue of launching from a balloon, particularly w.r.t. orientation for launching. A comparatively simple solid fueled two stage MAV with a cube-to-nano sat sized payload with a radio beacon of some sort - keep it as simple as possible. If you send a mid-scale rover in advance to get samples - then an MSL-scale lander could house both the MAV, and a contingency sample gathering micro-rover. The hard part is the on-orbit rendezvous - and how to convince people that you've got the samples very very tightly locked up.

Doug

Posted by: John Whitehead Oct 17 2007, 06:51 PM

You're right, nprev, that a solid first stage is very attractive. NASA's reference design concept for a MAV has been a 2-stage solid more or less since about 1999. The good news is that solid rocket motors on the scale of interest (100 kg give or take a factor of 2) are existing technology, and they are a whopping 90 percent propellant. However, there's devil is in the details. The thrust of such small solid motors is way more than is needed. It would reach high speeds while still low in the Mars atmosphere, so there's somewhat more aerodynamic drag than for a liquid MAV. Worse, perhaps, is that the high thrust also requires the directional control system to be larger and heavier than would otherwise be needed, and control must be very responsive (quick) to steer correctly for the 20 seconds or so before the first stage motor burns out.

Solid motors and their payloads are usually spinning when used for space maneuvers. Launching a spinning MAV would require the lander to have a spin table rigidly anchored to the ground so it doesn't start wiggling when the MAV is spun up. The landing orientation cannot be guaranteed, so the launch platform would require tilt adjustments on two axes, and then still be rigid when it starts spinning. How to design such a lander or estimate its weight to compare with other options? A spinning MAV was considered at NASA in 1998-1999 and ruled out.

Pressurizing the "heck" out of tanks and leaving the pumps on Mars is not a solution because the high-pressure tanks would be way heavier than pumps.

You hit 2 nails on their heads, monitorlizard.
1. There are so many different kinds of rockets and missiles out there, that it is way too easy for the "collective consciousness" to assume that it is possible to just go and buy something that can launch off of Mars. Therefore there has been no NASA (or ESA) money dedicated to aggressive technology development, most likely necessary.
2. Minimum size for avionics is really what determines the smallest MAV. Who wants to make the agonizing decision about how much telemetry to put on board? If it doesn't reach Mars orbit, how much data is needed to know why the multi-billion dollar mission failed (the painful lesson from Mars Observer 1992).

Rising through the atmosphere with a helium balloon before launching the rocket would be the ideal way to get off of Venus, if only the balloon could be kept from melting.

So for Mars ascent there are several possible solutions, none of which is existing technology. Ideally, some amount of engineering effort (building and testing things) would be affordable for each candidate, to help sort out what makes sense to pursue further.

John W.

Posted by: Jim from NSF.com Oct 18 2007, 12:34 AM

QUOTE (John Whitehead @ Oct 17 2007, 02:51 PM) *
Pressurizing the "heck" out of tanks and leaving the pumps on Mars is not a solution because the high-pressure tanks would be way heavier than pumps.



But not too heavy for a MAV

Posted by: nprev Oct 18 2007, 01:21 AM

QUOTE (John Whitehead @ Oct 17 2007, 11:51 AM) *
The good news is that solid rocket motors on the scale of interest (100 kg give or take a factor of 2) are existing technology, and they are a whopping 90 percent propellant. However, there's devil is in the details. The thrust of such small solid motors is way more than is needed. It would reach high speeds while still low in the Mars atmosphere, so there's somewhat more aerodynamic drag than for a liquid MAV.


John, I admit my ignorance with respect to propellant chemistry, but would it perhaps be possible to formulate a solid fuel mixture that would provide adequate--well, the correct amount is what I really mean--thrust for Martian conditions? Seems easier than designing the MAV for different (and possibly quite variable) atmospheric conditions with COTS booster thrust as a constant.

Posted by: John Whitehead Oct 18 2007, 01:41 AM

QUOTE (nprev @ Oct 18 2007, 01:21 AM) *
John, I admit my ignorance with respect to propellant chemistry, but would it perhaps be possible to formulate a solid fuel mixture that would provide adequate--well, the correct amount is what I really mean--thrust for Martian conditions? Seems easier than designing the MAV for different (and possibly quite variable) atmospheric conditions with COTS booster thrust as a constant.


nprev, I'm happy to admit I'm not a solid rocket expert. But when I've asked solid rocket experts, there is no definitive answer to this question. I fall back on George Sutton's book. Thrust is determined by total mass flow (of burnt stuff), which is proportional to the exposed area of the propellant grain, times the regression rate of a given propellant. Smaller motors have a higher ratio of burn area to propellant mass, hence short burn times. Burn area relative to volume can be reduced by making the solid motor long and skinny, an "end burning" propellant grain. Then how does that package up as a MAV stage (bending modes, more inert wall mass, and it doesn't fit in the spacecraft on the way to Mars).

How do you make a mixture of fuel and oxidizer burn slower? The best of my understanding is that you have to dilute it with something, i.e. lower temperatures, lower Isp, lower exhaust velocity. I wish the rocket companies would publish a paper or advertise their capability to produce low-thrust solid motors. My personal bet is that it's not going to happen.

Posted by: nprev Oct 18 2007, 01:51 AM

Thanks, John.

Hmm...sounds like a real challenge in systems engineering...so many interdependencies! I've got some former classmates still looking for thesis research topics; this sounds like a goodie. Will see if anyone's interested.

Posted by: tty Oct 18 2007, 08:35 AM

QUOTE (John Whitehead @ Oct 18 2007, 03:41 AM) *
Burn area relative to volume can be reduced by making the solid motor long and skinny, an "end burning" propellant grain. Then how does that package up as a MAV stage (bending modes, more inert wall mass, and it doesn't fit in the spacecraft on the way to Mars).


That ”long and skinny” comment is interesting. About the only existing solid rocket motors in the correct size class are for BVR AAM’s, and these tend to be “l,ong and skinny” both for aerodynamic reasons and because they do have fairly long burn times (=fairly long flight times). Perhaps a derivative AIM120 engine might be suitable for a first stage? As for control thrust-vectoring is used in modern AAM’s, though usually only in agile short-range missiles. So most of the technology does exist, but not in a form that is immediately usable.

Posted by: mcaplinger Oct 18 2007, 08:37 PM

QUOTE (nprev @ Aug 18 2007, 09:09 PM) *
even a very little bit of Mars would go a long. long way in terms of answering fundamental/nagging questions such as the presence or absence of superoxides, carbon abundance/source, iridium ratios, etc...

Many of these questions could be far more cost-effectively answered with in situ measurements than by sample return, and some of the others could be answered by a much simpler SCIM-type mission. And some we more or less know already from the SNCs.

Frankly, because of the fundamental energetic difficulties and the valid-or-not "Andromeda Strain" concerns, I'm a little surprised that people are still seriously talking about Mars sample return as a likely mission for the foreseeable future.

Posted by: hendric Oct 18 2007, 09:44 PM

There are some hybrid rockets, that have a solid fuel core and a liquid oxidizer. I believe the SpaceshipOne rockets were of this type provided by SpaceDev. They have throttleable and restartable rockets. So only one pump needed:

http://www.spacedev.com/spacedev_hybrid_prop.php

Posted by: John Whitehead Oct 18 2007, 11:42 PM

QUOTE (tty @ Oct 18 2007, 08:35 AM) *
That ”long and skinny” comment is interesting. ...control thrust-vectoring is used in modern AAM’s, though usually only in agile short-range missiles. So most of the technology does exist, but not in a form that is immediately usable.


Yes I suspect an off-the-shelf AAM motor would not have the required propellant fraction, and I agree with the intended meaning of that last line. It raises a key consideration which might sound like semantics, but bear with me. In the world of solid state advances (computer chips etc.), having "the technology" in hand often means something completely unrelated to "how heavy is the final packaged product." We are surrounded by the notion that implementation and technology are separate things. However, in the world of high performance rockets, the question of whether the hardware is lightweight enough is really not a separate issue. The weight is the main problem that needs to be solved. Most flying things that exist have already been evolved to a practical limit of least weight, given material strength versus the stress loads from internal pressure, thrust, flight vibrations, etc. Can we start with an existing solid stage that has directional control, and carve out a third or a half the weight? If we succeed at doing so, did we have to make innovations along the way that could rightly be called "new technology"?

Offered as food for thought.

In all cases of evaluating what might work for a MAV, the most concise answer to the question is a mass budget for the vehicle, initially supported by calculations showing realistic departures from proven capability, and ultimately supported by a complete design and a working vehicle that meets the need for delta V.

John W.

Posted by: nprev Oct 19 2007, 12:59 AM

Hate to even bring this up, but it sure seems like we might need to fly a pathfinder technology demonstration mission before committing to the real deal...and the nasty part here is that there's no place to do it & gain any value at all in engineering terms but Mars itself.

Aside from the truly formidible problems of designing a MAV, there are a bunch of other systemic complexities and event dependencies to consider, far more IMHO than in any other UMSF effort to date. I wonder if a high-risk Discovery-class mission could designed to send a few grams back of any random Martian surface material as a bonus; the real value would be assessing the performance of all these subsystems.

Posted by: John Whitehead Oct 19 2007, 01:10 AM

QUOTE (Jim from NSF.com @ Oct 18 2007, 12:34 AM) *
But not too heavy for a MAV


If the pressure-fed versus pump-fed question is to be debated, then mass budgets need to be compared. Descending down one layer into what determines the mass budget, one key question is how heavy are the tanks relative to the propellant they contain? Is there stored gas on board to push the propellants out, and how heavy are the extra tanks (or extra tank volume) for storing the gas?

Regarding the earlier suggestion to fill it up with Mars atmosphere then leave pumps on the ground, note that the Mars atmosphere is carbon dioxide, which is 11 times as heavy as helium. A good rule of thumb is that the best aerospace pressure vessels flying today can contain 1/4 of their own weight in helium. Or to put that a different way, the helium needed weighs only 1/4 of the vessel. If carbon dioxide were to be used instead, it would weigh more than the propellant tanks and gas storage vessel(s) combined. What does this look like on the mass budget?

Back in 2001, NASA funded 3 companies to go and design Mars ascent vehicles. The results, made public by AIAA paper number 2002-4318, were:
Lockheed-Martin, 268 kg solid rocket
TRW, 254 kg gel propellant rocket
Boeing, 400 kg pressure-fed liquid bipropellant (hypergolic)
These numbers don't count the mass of essential hardware that remains on Mars, just to support the launch.

The pressure-fed liquid was the heaviest option, and in recent years, all three have been considered too heavy to do the MSR mission within the Mars science budget. All this leads to the conclusion that it's really a nitty-gritty technology problem that is unlikely to be solved in the usual way by engineering design studies.

Before I forget to mention them again, here are two fun-to-read articles that offer an inside view of the people at NASA as they have worked to figure out the MAV. I'm going to mark this spot with a Mars so these refs can be found easily scrolling through here.
mars.gif

Reichhardt, "The One-Pound Problem," Air & Space (the Smithsonian's magazine), October-November 1999, page 50. I have read it online at http://www.AirAndSpaceMagazine.com/ASM/Mag/Index/1999/topp.html but if you can find the original in a library there are some nice artist concepts too. That article was written just before two Mars-bound spacecraft were lost, and years later the conclusions in that article turned out not to be the final answer.

The other is a two-part personal perspective by Dr. Mark Adler of JPL, on the Planetary Society blog in September 2006, http://www.planetary.org/blog/article/00000701/ and Part Two the next day at http://www.planetary.org/blog/article/00000703/

John W.

Posted by: John Whitehead Oct 19 2007, 01:26 AM

QUOTE (nprev @ Oct 19 2007, 12:59 AM) *
Hate to even bring this up, but it sure seems like we might need to fly a pathfinder technology demonstration mission before committing to the real deal...and the nasty part here is that there's no place to do it & gain any value at all in engineering terms but Mars itself.

Aside from the truly formidible problems of designing a MAV, there are a bunch of other systemic complexities and event dependencies to consider, far more IMHO than in any other UMSF effort to date. I wonder if a high-risk Discovery-class mission could designed to send a few grams back of any random Martian surface material as a bonus; the real value would be assessing the performance of all these subsystems.


Maybe launch the MAV from a high-altitude balloon above earth, to simulate the atmospheric density on Mars. It wouldn't reach orbit, but the trajectory would tell how well it worked.

NASA has considered a bare-bones "scoop of dirt" mission. It is a tough decision to spend all that money without sending science instruments and/or a rover and/or a rock drill.

Posted by: JRehling Oct 19 2007, 05:30 AM

[...]

Posted by: djellison Oct 19 2007, 07:27 AM

QUOTE (nprev @ Oct 19 2007, 01:59 AM) *
a high-risk Discovery-class mission could designed to send a few grams back of any random Martian surface material as a bonus;


I can't imagine how you would land on Mars at all for a Discovery budge - let alone with any form of sample return ability. The only thing in that scale you could do is the SCIM proposal that is forever turned down in Mars Scout AO's

Doug

Posted by: Mark Adler Nov 4 2007, 11:52 PM

QUOTE (djellison @ Oct 19 2007, 12:27 AM) *
I can't imagine how you would land on Mars at all for a Discovery budget

Apparently what you do is use leftover hardware from a previous, cancelled Mars landed mission. Phoenix plans to land on Mars on essentially a Discovery budget.

But yes, just getting MSR halfway back (e.g. to low Mars orbit) is not even in the ballpark of Discovery/Scout budgets.

Posted by: ElkGroveDan Nov 5 2007, 02:19 AM

And wouldn't you know it, I bet there isn't any leftover Martian orbital ascent hardware lying around anywhere, is there?.

Posted by: dvandorn Nov 5 2007, 07:04 AM

I dunno, Dan -- the last MSR concept I saw (back in the late '90s) used some leftover, off-the-shelf solid-fuel military missile as its basis for an ascent vehicle. I bet there are at least two or three of them left that haven't been fired in anger yet... rolleyes.gif

-the other Doug

Posted by: djellison Nov 5 2007, 07:59 AM

QUOTE (Mark Adler @ Nov 4 2007, 11:52 PM) *
Phoenix plans to land on Mars on essentially a Discovery budget.


I thought it was planning to land on ice deposits smile.gif

It's a fair point - but if you take the '01 hardware costs, the scout budget, and the little-bit-extra - Phoenix isn't something you could do from the ground up for a discovery budget. If you got to a genuine 'build to print' state, maybe it'd work?


Doug

Posted by: PhilCo126 Nov 5 2007, 11:12 AM

Well, don't want to start any debates but remember:

The very first unmanned (Lunar) sample return mission:
http://en.wikipedia.org/wiki/Luna_16

basic MSR JPL-weblink
http://mars.jpl.nasa.gov/missions/samplereturns.html

huh.gif

Posted by: ElkGroveDan Nov 5 2007, 03:11 PM

QUOTE (PhilCo126 @ Nov 5 2007, 03:12 AM) *
The very first unmanned (Lunar) sample return mission:
http://en.wikipedia.org/wiki/Luna_16

Speaking of left over equipment ohmy.gif

That thing looks like it was made from an old oil drum and surplus scuba gear.


Posted by: PhilCo126 Nov 5 2007, 07:46 PM

Indeed an awkard looking spacecraft and this 'thing' had a weight of almost 2000 kilograms with the ascent stage over 500 kilograms... and the upper 'ball' (in fact the sample re-entry capsule) had a diameter of 30 centimeters... of course the whole thing 'only' had to escape the Moon's gravity wink.gif
When we compare the 1971 Mars 2 or 3 spacecraft configuration, it looks almost identical to the Luna 9 or 13 surface capsules. So probably a Soviet-Russian MSR craft might have looked like the 'ugly' Luna 16?

Posted by: nprev Nov 6 2007, 02:08 AM

Might be worth considering & contrasting US & old Soviet-era (SE) design approaches when thinking about MSR. From what I gather, most SE flight hardware was very rugged, implying that functional modules were optimized for their specific performance, and holistic system interfaces/dependencies were minimized in order to reduce risks. The US approach was almost diametrically opposite, relying instead on a robust C&DH capability to adaptively sequence critical events, which in turn allowed more trade space with respect to subsystem performance margins.

Wonder if there just might be a truly optimal middle ground, here...

Posted by: John Whitehead Nov 7 2007, 11:09 PM

QUOTE (nprev @ Nov 6 2007, 02:08 AM) *
Might be worth considering & contrasting US & old Soviet-era (SE) design approaches when thinking about MSR. ...functional modules were optimized for their specific performance....


I was recently fascinated to learn how the Soviet Luna (16, 20, & 24) achieved its ascent and earth return. Yes, it was functionally very simple engineering, tailored to the particular physical situation. The moon's small size (compared to Mars) permitted a direct return. Not going into lunar orbit meant no circularization (orbit insertion) burn, and the fact that the target (earth) was gravitationally large and nearby meant no midcourse corrections either. No need for any engine restarts or staging. A single propulsive burn from the 1-stage ascent vehicle was simply timed (both moment of launch relative to the calendar, and burn duration).

Guidance consisted of flying a vertical trajectory off the moon. The vernier engines were controlled by a local vertical sensor, a pendulum! Site selection was limited to the east side of the moon, where a vertical ascent reduced the geocentric velocity compared to the moon's, so it was effectively just a deorbit burn with respect to the earth. Velocity would have been less than lunar escape velocity, since the earth was sitting there pulling it home. The return stage had a transmitter that could be switched on and off by commands from earth, and the resulting signals received on earth were used to predict the landing point accurately enough to go out and find it.

All this is explained in a paper by Boris Girshovich, presented at the National Space Society's 26th International Space Development Conference, Dallas Texas 2007May25-28. See isdc.nss.org/2007/index.html.

My notes from reading the above paper say that the earth entry capsule was 3 feet in diameter, while the above posting from PhilCo126 a couple days ago says 30 cm. I suspect both numbers are from memory or word of mouth, so does anyone have any solid references to cite here? Has anyone been to Russia where the capsule is presumably in a museum somewhere?

Mars ascent is MUCH harder to do, considering the need for a smaller size, higher delta velocity, double the thrust-to-weight, and more complicated navigation to orbit.

John W.

Posted by: nprev Nov 8 2007, 01:31 AM

Fascinating & ingenious; really doing more with less. Thanks, John!

Maybe the way to approach this is to design a mission based on what we know we can do, rather then what we hope to be able to develop. (This is not meant to limit technological advance, but instead to constrain the problem). For example, if we assume direct EDL and payload DTE return, this simplifies the mission requirements considerably in some ways but possibly complicates them in others (one being the ability to meet really tight launch windows from Mars to Earth).

Just throwin' that out there...

Posted by: John Whitehead Nov 8 2007, 01:54 AM

QUOTE (dvandorn @ Nov 5 2007, 07:04 AM) *
...leftover, off-the-shelf solid-fuel military missile as its basis for an ascent vehicle.
-the other Doug


Couldn't resist running a quick & dirty trajectory simulation to compare a MAV with military missiles. First verified the flight of a 100-kg MAV by running the trajectory simulation to reach a 500-km circular Mars orbit using about 4150 m/s delta velocity (results match a previous case in the Journal of Spacecraft & Rockets, Nov 2005 p. 1041). Then simulated flight of the same vehicle starting on earth. Had to increase thrust 50 percent so it exceeds earth weight of the vehicle. To reduce the effect of the thick atmosphere on such a tiny vehicle, moved the launch site to 10 km altitude (32,800 feet). The latter seems fair for comparison to air-to-air missiles, which might launch at such an alitude.

The simulation result indicates that a 100-kg Mars ascent vehicle launched 10 km above earth can go more than 500 km downrange. Now, what military missile in this size class has such a capability?

Take a look at www.designation-systems.net, and click Directory of US Military Rockets and Missiles. Note the extensive list available in the selection box. As an example, the latest Sidewinder (AIM-9) is said to have a mass just under 100 kg, but its range is said to be only tens of kilometers. A Navy Standard Missile (RIM-156B or RIM-161) has roughly the same reach as a MAV, but it weighs about 1.5 metric tons. Based on these 2 examples, military missiles appear to offer only a tenth the distance relative to mass, compared to what Mars ascent needs.

While it might be possible to push solid rocket technology toward sufficiently less inert mass to make a solid-propelled MAV, there is no indication that anything off the shelf is capable. If performance details for military missiles and their rocket motors could all be public, there would probably be a more widespread appreciation of just how much harder it is to make a MAV.

John W.

Posted by: John Whitehead Nov 8 2007, 02:27 AM

QUOTE (nprev @ Nov 8 2007, 01:31 AM) *
...if we assume direct EDL and payload DTE return, this simplifies the mission requirements considerably in some ways but possibly complicates them in others....


Small-scale rocket engineering would blossom if NASA decided to build a direct-to-earth Mars ascent vehicle. And I'm a rocket technology person, so I should promote that, right? But the MAV would be multiple tons, not just because of the 40 percent higher velocity, but also to lift an interplanetary spacecraft instead of a sample canister. Solar power, pointing a high gain antenna to earth, midcourse corrections, earth entry capsule, etc. would all have to be launched off of Mars. In addition, the gigantic Mars lander needed to put such a beastly MAV down on Mars, is another whole unsolved problem.

Over 10 years ago, JPL had preliminary design efforts for a DTE MAV because autonomous orbital rendezvous was understood to be an unsolved problem. In early 1997 I had a chance to talk with Donna Shirley, a manager on the rover team who later wrote a book, Managing Martians. I remember saying to her that anyone who solves the rendezvous problem would be making a far greater contribution (to MSR) than any rocket engineer ever could. Since then there has been progress on rendezvous, but no real money dedicated to MAV technology. mad.gif No money for a team of miniature launch vehicle experts means there is no one around to recognize that it actually needs work.

John W.

Posted by: dvandorn Nov 8 2007, 08:09 AM

QUOTE (John Whitehead @ Nov 7 2007, 08:54 PM) *
Couldn't resist running a quick & dirty trajectory simulation to compare a MAV with military missiles...

...While it might be possible to push solid rocket technology toward sufficiently less inert mass to make a solid-propelled MAV, there is no indication that anything off the shelf is capable. If performance details for military missiles and their rocket motors could all be public, there would probably be a more widespread appreciation of just how much harder it is to make a MAV.

The only corroboration I can find right now that the 2003-2005 MSR concept was to use military hardware is Steve Squyres' comment, in "Roving Mars," that the mini-MAV being planned for use in conjunction with the Athena rovers was "based on a classified Navy program." He also mentions the program had been in existence since 1958.

Squyres says that the payload this mini-MAV was to have lofted into low Mars orbit would have been about the size of a coconut. I imagine this would have weighed significantly less than 100 kg -- maybe only 20 to 30 kg.

The 2003-2005 MSR concept was that two different MSR landers would be flown, each serviced (i.e., loaded with samples) by one of the Athena rovers. An RTE vehicle would then rendezvous with and "gobble up" each of these coconuts and then burn back out of Mars orbit into an Earth return trajectory. (No matter what else happened, this means the two coconuts would have to have been launched into identical orbital planes, or else the RTE vehicle would never be able to carry enough fuel to rendezvous with them both.)

-the other Doug

Posted by: AndyG Nov 8 2007, 09:43 AM

QUOTE (John Whitehead @ Nov 7 2007, 11:09 PM) *
The vernier engines were controlled by a local vertical sensor, a pendulum!

Hi John - I'm rather wondering how that would work. If you're accelerating considerably above the level of local gravity, the pendulum will react to the centre of thrust as the local vertical. I could see a long, lazy arc being described back into the regolith.

Andy

Posted by: algorimancer Nov 8 2007, 02:28 PM

There's been discussion elsewhere of the concept of sending a vehicle with a supply of fuel (typically liquid hydrogen), then after landing extracting liquid oxygen from the Martian atmosphere by breaking-down CO2. There was even a plan to fly a test version of the system on one of the recent landers (possibly MPL, doesn't really matter, it was dropped). This seems like a promising direction for MSR. Further, with the more recent establishment of the existence of water ice near the surface over much of Mars, simple electrolysis (via solar power) would allow production of both fuel and oxidizer on site, so this simplifies the MSR problem to that of delivering an empty launcher to the surface, along with associated equipment to generate the oxidizer (and perhaps fuel).

Posted by: mcaplinger Nov 8 2007, 02:28 PM

QUOTE (AndyG @ Nov 8 2007, 01:43 AM) *
I'm rather wondering how that would work. If you're accelerating considerably above the level of local gravity, the pendulum will react to the centre of thrust as the local vertical.

Regardless of the acceleration, the pendulum will always react to the vector sum of the gravity vector and the acceleration vector, so if you want to fly antiparallel to the gravity vector, this should work fine.

Posted by: mcaplinger Nov 8 2007, 02:44 PM

QUOTE (dvandorn @ Nov 8 2007, 12:09 AM) *
The only corroboration I can find right now that the 2003-2005 MSR concept was to use military hardware is Steve Squyres' comment, in "Roving Mars," that the mini-MAV being planned for use in conjunction with the Athena rovers was "based on a classified Navy program." He also mentions the program had been in existence since 1958.

http://www.lpi.usra.edu/meetings/robomars/pdf/6052.pdf and the AIR&SPACE article referenced earlier in the thread. Basically this was the MiniMAV concept, which was found to have some overly optimistic assumptions.

Posted by: John Whitehead Nov 8 2007, 08:04 PM

QUOTE (dvandorn @ Nov 8 2007, 08:09 AM) *
...Steve Squyres' comment, .... mini-MAV ... was "based on a classified Navy program." ...1958.
Squyres says that the payload .... size of a coconut. I imagine... 20 to 30 kg.
The 2003-2005 MSR concept ... An RTE vehicle would then rendezvous with and "gobble up" each of these coconuts and then burn back out of Mars orbit into an Earth return trajectory...
-the other Doug


The Mini-MAV idea was advanced by Brian Wilcox of JPL, whose father had worked on the noted Navy program circa 1958. The latter was a "hail Mary" attempt at China Lake to put a U.S. object into orbit as a quick response to Sputnik. The main trick was to use several spin-stabilized solid rocket stages, which made the vehicle smaller by deleting guidance & control hardware. Brian explained all this at the AIAA Joint Propulsion Conference in 2001, AIAA paper number 2001-3879.

Later studies of the concept by JPL and contractors resulted in putting the G&C back on. The conceptual design eventually grew from Brian's 20 kg to the latest reference design at 268 kg, too heavy to implement MSR using the MSL 2009 landing system (the largest Mars lander ever developed). The coconut-size sample container has remained the notional payload design for a MAV. Yes, launching a coconut off of Mars with a vehicle smaller than ~200 kg remains THE unsolved problem.

The quote attributed to Steve Squyres is a perfect example of the rampant collective optimism that a Mars ascent vehicle is going to appear from behind a curtain. NASA, JPL, and their contractors have done such a tremendous job of pulling off technological "miracles" for Mars spacecraft, that the implementation of missions is too easily taken for granted.

John W.

Posted by: John Whitehead Nov 8 2007, 08:27 PM

QUOTE (algorimancer @ Nov 8 2007, 02:28 PM) *
...simple electrolysis (via solar power) would allow production of both fuel and oxidizer on site, so this simplifies the MSR problem to that of delivering an empty launcher to the surface, along with associated equipment to generate the oxidizer (and perhaps fuel).


In-situ propellant production is something that fits in with colonizing Mars, but scaling it down for robotic missions is very optimistic. The ground support equipment for a vehicle with cryogenic propellants would be heavy (cryogenic disconnects, chilldown, etc.). The equipment to produce, liquefy, and then store those propellants on Mars with refrigeration would not be simple, and it would all most likely be heavier than the propellants loaded into the MAV. In addition, cryogenic launch vehicles work much better on a large scale, where there is enough propellant volume relative to the surface area (i.e. entering heat) to endure the boiloff.

John W.

Posted by: nprev Nov 9 2007, 03:05 AM

Understood. KISS has to be the guiding principle here, which is why I was pushing emulation of the Soviet design philosophy, at least for the Mars-to-Earth return phase. There are some truly formidible risks there that must be mitigated.

Posted by: mcaplinger Nov 9 2007, 04:53 AM

QUOTE (nprev @ Nov 8 2007, 07:05 PM) *
KISS has to be the guiding principle here, which is why I was pushing emulation of the Soviet design philosophy, at least for the Mars-to-Earth return phase.

As Einstein said, "as simple as possible but no simpler." The history of MSR design is full of ideas that are simpler than possible. rolleyes.gif

Posted by: algorimancer Nov 9 2007, 02:39 PM

QUOTE (John Whitehead @ Nov 8 2007, 02:27 PM) *
... scaling it down for robotic missions is very optimistic. The ground support equipment for a vehicle with cryogenic propellants would be heavy ....


Yes, dealing with cryogenic storage of fuel and oxidizer seems the major showstopper to doing this with a single lightweight mission. I don't suppose in-situ manufacture of solid propellant might be an option - I gather that assembling this sort of thing is routinely done by advanced rocketry hobbyists, but the resin used in producing an ammonium perchlorate composite propellant seems unlikely to be an option. An old fashioned gunpowder-based propellant might be feasible (Carbon from CO2, sulfur from sulfates, potassium nitrate from ?). Evaporite deposits seem to concentrate lots of interesting chemicals. Propellant chemistry is well beyond my realm of expertise, however.

Posted by: hendric Nov 9 2007, 10:47 PM

What about using a coilgun to give the payload an initial boost? I think a 2+km/s gun should be feasible to launch a small payload, say 20kg. The beauty is the simiplicity, you just charge some capacitors, load the projectile, steady yourself against the ground, and launch. If the design is done well, it might be possible to launch multiple return projectiles, say one every month with charging.

IEEE Spectrum just recently had an article about the history of railguns and coilguns and the like:

http://spectrum.ieee.org/jul07/5296


Course, might as well be wishing for magic ponies to fly the MAV off of Mars. smile.gif

Posted by: JRehling Nov 12 2007, 08:10 PM

[...]

Posted by: YesRushGen Nov 13 2007, 03:46 PM

QUOTE (JRehling @ Nov 12 2007, 03:10 PM) *
As soon as we get that Mars-to-orbit launch vehicle, let's see if it's easily modifiable to work at 900F with double the escape velocity.


That, and don't forget that dense SOUP either! laugh.gif

Posted by: tty Nov 14 2007, 11:13 PM

Even without the heat a take-off from Venus is almost as difficult as from Earth, and that thick atmosphere means extreme drag and dynamic pressure. You would probably have to lift the booster out of thickest stuff with a balloon before ignition

As a matter of fact a Titan sample return would probably be rather easier (and more interesting) than a Venus sample return.

Posted by: gndonald Dec 6 2007, 01:40 PM

QUOTE (mcaplinger @ Nov 9 2007, 01:53 PM) *
As Einstein said, "as simple as possible but no simpler." The history of MSR design is full of ideas that are simpler than possible. rolleyes.gif


Such as this one, which is not necessarily simpler, but still interesting. Back in the 70's some consideration was given to modifying a Viking lander by removing everything but one camera, the sample arm, the S band transmitters and the power supply, then replacing what was removed with a sample return rocket.

This would be carried to Mars by one Viking Orbiter, another Viking Orbiter would carry the Earth Return Stage.

At the appointed time the sample return rocket would be launched, rendezvous with the Earth Return Stage and the contents sent back to Earth for analysis.

It's quite clear from the study (see links below) that all other science was going to be sacrificed in favor of the return of the Martian Soil sample.

See:

1. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750006729_1975006729.pdf

2. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750006730_1975006730.pdf

 

Posted by: Cugel Dec 21 2007, 01:14 PM

International Group Plans Strategy For Mars Sample Return Mission

http://www.marsdaily.com/reports/International_Group_Plans_Strategy_For_Mars_Sample_Return_Mission_999.html

Some pretty good news, I would say.

Posted by: nprev Dec 21 2007, 01:24 PM

Thanks, Cugel. smile.gif

I like the extensive international cooperation, but worry about 'requirements wars'. It can be pretty damn difficult to reach a consensus with a large cardinal number of stakeholders from different organizations. Hopefully, the mission definition will be as clear-cut as possible to avoid this mess, 'cause it ain't fun at all, plus such wars tend to really jack up costs... sad.gif

Posted by: vjkane Dec 22 2007, 05:02 PM

QUOTE (nprev @ Dec 21 2007, 01:24 PM) *
I like the extensive international cooperation, but worry about 'requirements wars'. It can be pretty damn difficult to reach a consensus with a large cardinal number of stakeholders from different organizations. Hopefully, the mission definition will be as clear-cut as possible to avoid this mess, 'cause it ain't fun at all, plus such wars tend to really jack up costs... sad.gif


I think a sample return could be pretty clear cut for international cooperation. Here's one break down that could make sense:

Rover caches:

ESA - ExoMars
USA - Follow on rover to MSL (astrobiology field rover?)
USA - MSL as backup

Lander and ascent craft

Nation n: Cruise, landing stages
Nation n: Rover to get cached samples
Nation n: Ascent vehicle

Retrieval craft

Nation n: Cruise craft to reach Mars and Mars orbital operations
Nation n: Earth return craft to leave Mars orbit and cruise craft
Nation n: Earth entry craft

This breakdown assumes one particular MSR architecture (separate craft to retrieve samples from Mars orbit) but many others are possible. I think the sample return mission makes international cooperation easier than in most missions.

Posted by: John Whitehead Jan 15 2008, 11:52 PM

Some 'current events' which indicate an increasing emphasis on MSR:

January 2008: This month's issue of Aerospace America has an article titled "Mars Exploration: Digging Deeper," by Leonard David, contributing writer. MSR is featured prominently. The argument is made that the Mars Program needs to keep doing new and exciting things to justify its 46% share of NASA's planetary budget. More orbiter and rover missions alone might not be enough to maintain excitement and political support. On the other side of that coin is a concern that MSR might displace ongoing Mars efforts to such a large degree that there would be a net detriment to the Mars Program and to Mars science. One interviewed science leader expressed the importance of having MSR become an ongoing program to encompass multiple missions, rather than one win-or-lose flagship mission.

Given all these concerns, a way must be found to make MSR affordable for multiple attempts within the current budget (just over a half billion US dollars per year). However, the article did not delve into the unique technology needs for MSR.

My own comments: Is there anything that affects the mission scale and cost more so than the need to deliver a launch vehicle and its ground support equipment to another planet? Is there a more direct path through the above dilemma than building a miniature launch vehicle (or at least finding out definitively how small one can be)?

February 20-21, 2008: The Mars Exploration Program Analysis Group (MEPAG) is meeting in Southern California. Sample return is on the agenda for this discussion among (mostly) geologists. See http://mepag.jpl.nasa.gov/meeting/feb-08/index.html

April 21-23, 2008: A science meeting in Albequerque is named "Ground Truth from Mars: Science Payoff from a Sample Return Mission." Sponsors include the Lunar and Planetary Institute and NASA. Discussion topics include Mars exploration strategy, sampling strategy, and specific topics in geology and astrobiology. See www.lpi.usra.edu/meetings/msr2008/8

Also in the near future, NASA is planning a MSR Technology Workshop to discuss the following topics:
1. Rendezvous and Sample Capture (in Mars orbit).
2. Earth Entry Vehicle (the part that lands in Utah like Stardust did).
3. Returned Sample Handling Technologies on Earth.
4. Sample Acquisition, Sample Handling, and Encapsulation on Mars (packaging for shipment to Earth).
5. Forward Planetary Protection and Organic Contamination (how to not contaminate Mars with Earth life and related chemistry).
6. Entry, Descent, and Precision Landing (for Mars arrival, improved from prior Mars landers).
7. Back Planetary Protection (how to avoid any possibility that Mars life or molecules could harm life on Earth).
8. Mars Ascent Vehicle.

Posted by: tty Jan 16 2008, 07:23 PM

QUOTE (John Whitehead @ Jan 16 2008, 12:52 AM) *
My own comments: Is there anything that affects the mission scale and cost more so than the need to deliver a launch vehicle and its ground support equipment to another planet? Is there a more direct path through the above dilemma than building a miniature launch vehicle (or at least finding out definitively how small one can be)?



As far as I can see there are three ways of acquiring martian samples without having to go all the way down into the gravity well and up again, and we have already been over them several times:

1. a Stardust type mission to collect dust from high in the Martian atmosphere

2. a sample return mission to Deimos or, preferably, Phobos. There is almost bound to be martian material there.

3. Go to Antarctica/Arabia etc and search for more martian meteorites (incidentally a project to go around the world's museums, particular the smaller ones, and see what they already have would very likely be successful - museum drawers are frequently the optimum locality to look for things)

Posted by: JRehling Jan 16 2008, 07:41 PM

[...]

Posted by: monitorlizard Jan 19 2008, 12:37 AM

Of course, nothing can compete with a well documented Mars sample returned to Earth, but I would like to say a few good words about Mars meteorites. They provide ground truth for parts of Mars' surface, we just don't know what parts of the surface. But just maybe CRISM or some future hyperspectral imager will be able to correlate some Mars meteorites with specific areas of the Martian surface. It won't be perfect, but Mars meteorites are an extraordinary bargain (cost-wise) that really do tell us a lot about Mars.

Posted by: edstrick Jan 19 2008, 01:29 PM

I think, maybe it was pointered to from here, that there's a major hi-geo-geek-level book coming out on the geochemistry, igneous petrology, and all the implications of that from the mars rock meteorites for the geology, geophysics and history of mars.

Posted by: JRehling Feb 21 2008, 09:21 PM

[...]

Posted by: vjkane Feb 21 2008, 09:53 PM

QUOTE (JRehling @ Feb 21 2008, 09:21 PM) *
I'm replying to this old post after reading up on the MSL landing site candidates.

John - You and I have ended up reaching the same conclusion -- we need several (I say at least 2, better 3; you say 4-5) sites sampled. I think this may be doable with enough partners: one does the rover, one the landing and ascent, one for the orbital retrieval. A couple of nits/questions. I talked with a senior Mars scientist in December who believes that once the MSL candidate sites are fully studied, they'll be lucky to have a choice of two. So there may not be that many sites that are safe to land on with foreseeable landing systems. Second, if we are going to keep the ascent vehicles cheap, how much more mass is needed to launch into a polar orbit versus an equatorial orbit? I think we may have to select from equatorial sites, only, if the mass penalty is too large.

Posted by: dvandorn Feb 22 2008, 06:00 AM

Well, here's another thought -- instead of relying solely on Mars Orbit Rendezvous (MOR) to collect up all of your separately-launched samples, why not add to this with an element of Mars Surface Rendezvous (MSR)?

It seems to me that the most challenging part of this architecture, both to land on Mars and to get back up off of it again, is the ascent vehicle.

If you want to sample six types of terrain, would it make sense to land six ascent vehicles and then go hunt their easter eggs in Mars orbit, using up tremendous amounts of propellants in rendezvous maneuvers? Or would it make *more* sense to land only two ascent vehicles, each of which is loaded with samples from three different rovers? (I'm thinking that it *must* be easier and cheaper to design, build and fly two MAVs which can each place 30 kilos of samples into orbit than it is to fly six such vehicles which can each loft 5 kilos of samples.) Yeah, you'd "bunch up" each set of three rover sites into something like 100-km circles around each MAV (assuming your rovers can drive as far as 50 km to deliver their samples), but that seems a small price to pay. Besides, there must be many locations on Mars where you can access several different and interesting geological units within a 100-km circle.

Granted, you'd be betting that your rovers would be able to navigate to your ascent vehicles. But again, success could be a graded event -- if only one of your ascent vehicles worked, or if only one or two rovers were able to deposit samples in each, you'd still be looking at a pretty successful mission.

And you'd only need enough fuel in your Earth return/orbiter vehicle to make two rendezvous maneuvers, not six. That could be a truly substantial mass savings.

Yes, we're talking about spending something similar to what Apollo cost just to get 50 or 60 kilos of Mars back to Earth -- at least four major Ares V-type launches, probably more, and a *lot* of spacecraft all operating at once cost a lot of money. But it's a fraction of what putting men on Mars will cost, and a lot of people would argue it's scientifically justifiable.

-the other Doug

Posted by: JRehling Feb 22 2008, 08:12 AM

[...]

Posted by: dvandorn Feb 22 2008, 04:29 PM

Well -- in re rendezvous issues, my thoughts come back to the fact that the U.S. has yet to prove a capability of autonomous rendezvous. A DoD test was attempted a few years ago, and it ran out of fuel before it achieved station-keeping with its target.

I grant you that the Russians have been doing it for years, and the Europeans will be jumping into the fray within the next month. But that's in LEO, where ground tracking data can be instantaneously incorporated into a vehicle's on-board solutions.

I'm also thinking of how rendezvous works. Your sample-carrying pods will have to be the passive targets -- your weight penalties are highest for the vehicles that you actually land on Mars, so the extra prop you need for rendezvous maneuvers will all have to ride in your orbiter. Making multiple rendezvous means you have to adjust the orbiter's orbit for every object you want to meet up with. Unless the sample pods are all in nearly identical orbits, and most importantly are in nearly the same place in those orbits at a given time, you could require from weeks to months of operations trying to reach each one. And if you end up with any significant out-of-plane elements, you exceed the available energy required to rendezvous pretty quickly.

So, for example, if you end up with two sample containers in nearly identical orbits but, say, separated by 120 degrees of orbit arc, you'll need to phase your orbiter back or forward through a third of an orbit, which is pretty energy-intensive.

And remember, you have to loft all of the fuel you need to reach your sample pods all the way from the surface of the Earth into Mars orbit. For every ounce of fuel you deliver to LMO, you have to spend thousands of pounds of propellants just to get it there.

Until and unless we demonstrate an autonomous rendezvous/docking capability in LEO that allows a satellite to travel around to various objects in various orbits, I'm not certain we're talking about sometihng that's within our technical competence at the moment...

-the other Doug

Posted by: Jim from NSF.com Feb 22 2008, 06:00 PM

QUOTE (dvandorn @ Feb 22 2008, 11:29 AM) *
Well -- in re rendezvous issues, my thoughts come back to the fact that the U.S. has yet to prove a capability of autonomous rendezvous. A DoD test was attempted a few years ago, and it ran out of fuel before it achieved station-keeping with its target.



That was DART, a NASA mission. The DOD test, Orbital Express, was very successful last fall

Posted by: JRehling Feb 23 2008, 12:31 AM

[...]

Posted by: edstrick Feb 23 2008, 11:04 AM

An essential ingredient in my utterly unofficial vote for a landing site would be the number of essentially DIFFERENT geologic units sampled. Meridiani, other than the sands on top, is essentially one geologic variations-upon-a-theme. Gusev has 2 major players: the basalt plains that buried what we really went there for, and the much older and much more complex and variable materials of the Columbia hills. The more essentially different materials a site has within the primary misison investigation range (and more beyond it), and the more of them that are of "special interest" in terms of paleo-habitable-environments or the like, the better. It would be great to have phylosilicates and sulfate deposits, plus deep seated igneous rocks and eolian layered sediments and channel wash deposits and ... and ... and...

Meridiani is wonderful.. and it's also boooooringgggggggg.

Posted by: vjkane Feb 23 2008, 03:59 PM

QUOTE (edstrick @ Feb 23 2008, 11:04 AM) *
It would be great to have phylosilicates and sulfate deposits, plus deep seated igneous rocks and eolian layered sediments and channel wash deposits and ... and ... and...

I was told by one Mars geologist that there's one place on mars that has the hematite and clay geologic units in close proximity. This is the soutwest Meridiani sites under consideration for MSL. He also said that there are concerns about the safety of the the site from a landing and roving perspective.

While edges of units would be nice (at least two geological provinces) you may not get the best examples of either unit there. Picking these sites is hard!

Posted by: vjkane Feb 29 2008, 01:56 AM

The journal Science just published a lengthy article on the Mars sample return debate. Unfortunately, Science is a subscription only journal. Much of the article rehashes history that is familiar to those of us who have followed the debate on this forum. I've put a couple of quotes from the article below on new information from the recent MPEG meeting:

"An expert panel assembled at the request of White House budget officials to vet the plan concludes that it doesn’t hold water. “You have to come clean,” says planetary scientist Philip Christensen of Arizona State University, Tempe, who chaired the panel. “Either you fund the program, or you accept the fact that it will be significantly reduced for the next decade.” Christensen laid out the panel’s conclusions at a 20 February meeting of the Mars
Exploration Program Analysis Group in Monrovia, California, with Stern sitting in the front row. The agency’s science chief insists that the new plan is sound and that the community is needlessly worked up about the proposed changes. “No missions have been canceled—none, zero, zip, nada,” he told Science. “The Mars program is really healthy,” he adds, noting that NASA might even hold a competition soon for a new Discovery mission that could be devoted to Mars...

"Christensen’s panel says that fiscal plan won’t fly. “The phasing is just wrong,” says Christensen. “Our assessment is that it just won’t work.” Preparing to launch a sample return by the end of the decade would require a big boost in spending earlier in the decade. The group determined that NASA would have to cancel everything after MSL—including the 2013 Scout and the 2016 missions—to fly a sample return by the second half of the next
decade. Stern, meanwhile, has slapped an $800 million cost cap on the 2016 mission, which he acknowledges would rule out the complex astrobiology field lab. Several scientists say that cap might also eliminate the rovers.
An alternative scenario would preserve the Scout mission and move the sample return back to 2022. But that would require using a poor orbital trajectory and create a dozen-year gap in U.S. landings on Mars, notes planetary scientist Lars Borg of Lawrence Livermore National Laboratory...

"Early estimates put the overall cost of such an ambitious mission at $5 billion to $6 billion. Stern says that NASA can contribute no more than $3 billion, and he hopes to attract another $1 billion or so from Europe— which is eager to participate— and possibly Japan." [The article goes on to say that the price would be lower if samples were returned that had been collected by MSL or ExoMars. It doesn't state that the MSL cache would be a jumbled cache of pebbles. However, it quotes the MPEG chairman, John Mustard, as saying that such a quick grab sample wouldn't be worth the trouble since we already have Mars meteorites.]

All in all, the article does a good job of describing the problem that Stern is trying to address in balancing the overall science program with the Mars program. Science is a highly reputable source, so I presume that the controversy over the feasibility of the program given projected funding is real. Stern seems to have his feet solidly planted on the ground, so I expect that there is another side to the story, though.

Posted by: mchan Mar 1 2008, 06:44 AM

Thanks for the summary of the article, vjkane.

Err, by the way, the group is MEPAG, not MPEG smile.gif

Posted by: nprev Mar 1 2008, 07:22 AM

Thanks also for the excellent summary, VJ; much appreciated! smile.gif

Sounds kind of scary, but at the same time hopeful; MSR is being seriously discussed, and that's really a first. Agree with the point that 'grabbing pebbles' may be fruitless; think we need to do a very focused sample recovery, and IMHO this probably means that we need to do more localized analysis missions al a the MERs & Phoenix, assisted by orbital recon before selecting a target for MSR.

"Focused" is probably too vague; what I mean is most likely to achieve prime science goals, and maybe it's time to refine those. We'd all like to see clays or sediments, and to be fair many would like to see igneous samples from the older terrain. Unfortunately, we'll have to make a choice; unless we're very lucky, no single site will provide a diverse sample set.

Posted by: Juramike Mar 29 2008, 03:00 PM

A really naive question:

Could you do a remote modular assembly of both the MAV (Mars Ascent Vehicle) and the RTE (Return to Earth) vehicle at Mars?

Final assembly/coupling would in Mars orbit (for the RTE vehicle) and on the martian surface (for the MAV).

You would require multiple vehicles to Mars, but you'd get the capability to spread the weight over several trips.


I picture a martian version of DEXTRE bolting together the MAV on the martian surface.

The tricky stuff to develop would be the remote orbital rendezvous capability (ESA's Jules Verne could become a test bed) and the autonomous remote assembly of spacecraft or structures. (Which seems like a really handy technology to develop.)

How whacked of an idea is this?

-Mike






Posted by: Greg Hullender Mar 29 2008, 05:46 PM

Controlled by someone on Earth or controlled by someone in Mars orbit?

--Greg

Posted by: Juramike Mar 29 2008, 05:59 PM

Automated sequence. Program sequence uploaded from Earth.

["SCRW DMNT" = the screw it, dammit! command laugh.gif ]

-Mike

Posted by: djellison Mar 29 2008, 06:06 PM

What would be the requirements ( size, mass etc ) for a MAV with cubesat-to-orbit type ability. I'd have thought it would make a lot of sense to forgo any on-Mars assembly at this stage and just take a solid fueled vehicle in one piece.

Of course, in the future, as a precursor to ISRU methane production - a liquid fueled MAV would be an interesting project - but with something with so many weak links and challenges as MSR - I think where the potential is there to KISS, it would be crazy to do otherwise. You want as few launches as possible.

Of course, even with an MSL or ExoMars cache - we have to presume they're dead. So you need to land close to them, and then go and get them with a rover ( MER-scale I guess) That's going to lead to something very special - revisiting a dead vehicle.

Doug

Posted by: imipak Mar 29 2008, 06:55 PM

Reading back through the thread, Climber posted a link to two excellent Planetary Society blog posts by Mark Adler on the two aborted MSR mission projects he worked on (post #4). (I'd forgotten those, if I ever read anything about them in the first place.) It looks a lot more practical than I thought, but even the most recent would only have returned a "grapefruit-sized" sample container; and you would probably want two landers at least, and it would have clearly been very expensive.

http://www.planetary.org/blog/article/00000701/, http://www.planetary.org/blog/article/00000701/.

As Climber pointed out, at the end he says he doubts a sample return will happen in the 2020 timeframe, or for "a few decades" to come.

Posted by: Juramike Mar 29 2008, 08:02 PM

(Link to http://www.planetary.org/blog/article/00000703/) smile.gif

Posted by: Juramike Mar 29 2008, 08:21 PM

QUOTE (djellison @ Mar 29 2008, 01:06 PM) *
but with something with so many weak links and challenges as MSR - I think where the potential is there to KISS, it would be crazy to do otherwise. You want as few launches as possible.


I agree, I think if we want to do a quick dash and grab from Mars, a simple system makes sense.

But if we are going to go back again and again (I'm very hopeful MSR won't be a one-shot deal), or begin to think about eventually bringing back larger samples, we'll need to start laying out the architecture that can do it.

(I also like the idea of sending smaller pieces that spread out the risk of Mars arrival failure. There will still be risk, but if one module fails to arrive, another could be sent. The increased risk would be on proper assembly and all the components working together - not insignificant, but one that will eventually have to be dealt with for future missions, like ISRU)

-Mike

Posted by: JRehling Mar 29 2008, 08:54 PM

[...]

Posted by: mcaplinger Mar 29 2008, 10:17 PM

It seems to be a foregone conclusion among many that MSR is the next major goal for Mars exploration.

I'm confused by this for two reasons (neither new to this forum but worth reminding everyone of):

1) I haven't seen any objective evaluation of the cost of sample return versus the cost of in situ measurements. For some large class of measurements, in situ would be far cheaper. Presumably this was the motivation for the "Astrobiology Field Lab". Is there a "sample return mafia" pushing for samples?

2) Fear of the "Andromeda Strain" scenario (justified or not) will impose all kinds of sterilization requirements on the returned samples, making MSR even more expensive.

I think MSR would be extremely cool, but I fear it won't happen for a long time.

I also note that Stern was pushing MSR back in mid-07, which seems at odds with the perception that he was advocating fiscal responsibility.

Posted by: algorimancer Mar 30 2008, 12:30 AM

QUOTE (mcaplinger @ Mar 29 2008, 04:17 PM) *
....sample return versus the cost of in situ measurements....

I too have wondered this for many years. I keep hearing it repeated that we have to bring samples back to Earth to do a really thorough analysis of the sample, but I have never seen a really convincing description of why this must be so. Sure, we have geology labs and associated equipment scattered all around the world, and I'm sure that hundreds of geologists would enjoy working on returned samples, but it has long seemed to me that it should be feasible to package lab equipment to send do Mars and do a rather thorough study in situ, particularly with the progress on miniaturization of electronics and MEMS and microfluidics. MER and MSL have some pretty good equipment for remote geology (chemical & mineral analysis) already. What is lacking? I might speculate that such things as a mass spectrometer and electron microscope would be helpful, as well as tools to study isotopic variation, but I can also envision packaging versions of these to drop on Mars, perhaps something like a base station lab package in conjunction with a mobile rover which roves about picking-up samples and periodically returning them to the lab. Such a lab may not replicate all the tools available on Earth, but it could well make up much of the current gap. Sure, some of this equipment is pretty heavy, but so is a MSR vehicle. What am I missing?

Posted by: SpaceListener Mar 30 2008, 12:58 AM

The project of MSR has one of the roots which is to develop and test the architecture for the future returning men's Mars explorers. Hence, the budget for this project must be split into several purposes such as this forum was discussing and also for the future men exploration to Mars.

Posted by: vjkane Mar 30 2008, 06:16 AM

QUOTE (JRehling @ Mar 29 2008, 09:54 PM) *
Deciding first that Apollo 12 / Spirit is the kind of terrain we are betting everything on seems like a really bad idea.

John, I agree with much of what you say. But I will play devil's advocate. There are lots of scientists who could learn a great deal about Mars with well documented samples from any of many places on Mars. They have the labs and just need the rocks. This cadre has been waiting patiently for their turn at enabling their science for decades since MSR was first seriously studied.

However, given the cost of MSR (probably $3B+), I don't think the return of a sample suite from just anywhere is worth the cost. I think it makes much more sense to put down more rovers (and give them proper caching equipment) to find the best site. I think we need rovers rather than stationary landers simply because it would take incredible luck to hit the one spot that reveals the material that tells you whether this is the place to sample or not. Look how far Spirit and Opportunity had to travel to make their discoveries. Imagine having a stationary lander in that crater that Opportunity landed in and never being able to get close to the bedrock a few meters away.

As for Netlander, I'd like to see each station carry a small Sojourner-sized rover with modern instruments to characterize just the local landing site.

We can have great fun and drink lots of beer trying to decide how to best find the place to send MSR to. The key discussion is whether to commit now or after a series of ground truth missions.

Posted by: imipak Mar 30 2008, 11:41 AM

QUOTE (algorimancer @ Mar 30 2008, 12:30 AM) *
What is lacking? I might speculate that such things as a mass spectrometer and electron microscope would be helpful, as well as tools to study isotopic variation, but I can also envision packaging versions of these to drop on Mars,..


I don't think it's practical to fly an STM, http://en.wikipedia.org/wiki/Scanning_tunneling_microscope#See_also smile.gif

Posted by: mcaplinger Mar 30 2008, 04:54 PM

QUOTE (imipak @ Mar 30 2008, 03:41 AM) *
I don't think it's practical to fly an STM...

What use would an STM be for geologic or astrobiological applications? For that matter, even electron microscopy was more confusing than useful in the case of ALH84001.

Phoenix has a mass spec, evolved-gas analyzer, and atomic force microscope. MSL has X-ray diffraction, mass spec/GC, and laser-breakdown spectrometry.

I'd be curious to see an objective analysis of the tradeoffs between sample return and in situ. You'd think one would exist.

Posted by: mcaplinger Mar 30 2008, 04:59 PM

QUOTE (SpaceListener @ Mar 29 2008, 04:58 PM) *
The project of MSR has one of the roots which is to develop and test the architecture for the future returning men's Mars explorers.

Certainly there is some useful information gained by unmanned missions for manned missions, but from a practical engineering requirements perspective the two have so little in common that the connection is weak at best.

For example, the US never did unmanned sample return as a precursor to Apollo, and the role of Surveyor in the development of Apollo was quite minimal (the LM had already been largely designed when Surveyor 1 landed, and I can't think of a single change in Apollo that came out of Surveyor experience; maybe someone can correct me.)

Posted by: dvandorn Mar 30 2008, 05:23 PM

QUOTE (mcaplinger @ Mar 30 2008, 11:59 AM) *
...the US never did unmanned sample return as a precursor to Apollo, and the role of Surveyor in the development of Apollo was quite minimal (the LM had already been largely designed when Surveyor 1 landed, and I can't think of a single change in Apollo that came out of Surveyor experience; maybe someone can correct me.)

You're absolutely correct, none of the Surveyor findings led to any engineering changes in the Apollo system. What those findings did accomplish, however, was to validate that the Apollo design would work.

Had there been no unmanned lunar landers prior to the first Apollo landing, NASA may well have given in to Tommy Gold's insistence that the descending LM drop brightly-colored weights along its final descent path, with Armstrong having orders to positively confirm that the weights didn't sink into the dust before he committed to setting his LM down onto the surface...

-the other Doug

Posted by: JRehling Mar 30 2008, 11:40 PM

[...]

Posted by: nprev Mar 31 2008, 12:41 AM

Hmm. Lot of food for thought there, JR, as per your usual.

Your comments may imply that the Mars exploration strategy should be split into two different realms, geology and astrobiology. Framed in that way, then MSR would appear to be less important for geology, which these days relies more and more on remote sensing even for terrestrial applications. Therefore, MSR targets would be primarily selected for biological potential.

Of course, there would still be considerable opportunistic overlap between the two, but separating them administratively into much more distinct focus areas might refine mission objectives and proposals.

However, if we can find just one tiny little currently active hot spring then the whole astrobiology debate's over; that's where we'll go! An orbiter with an ultra high-res IR imager as well as with a fast visible imager to search for active, small plumes or sudden landscape changes might be the best investment we could make to limit overall mission creep. Life is more likely in chemically active areas.

Not cheap, but quite probably cheaper then 15 or 20 smaller missions to look for likely habitats. I'm still hoping that we get lucky with MRO.

Posted by: dvandorn Mar 31 2008, 01:42 AM

QUOTE (JRehling @ Mar 30 2008, 06:40 PM) *
...The geology issue could be fairly simple: You could do a lot of good by sampling one site, and while more is always better, a few would probably be excellent.

I will point out that the same was thought to be true of the Moon, and yet, even though Luna is obviously, just by cursory examination, comprised of two distinct rock types (the darker mare and the lighter terrae), Apollo returned more than 100 pounds of samples before it returned a single conclusive chunk of anorthosite to pin down the majority composition of the terrae. And this was *years* after in-situ chemical analyses (with an alpha scattering spectrometer) demonstrated a terrae composition "compatible" with an anorthositic gabbro.

It's quite possible that there are crucial rock and terrain types awaiting us on Mars that are hidden or difficult to see and understand from orbit. We may miss something very, very important if we only go for "a few"...

-the other Doug

Posted by: algorimancer Mar 31 2008, 12:57 PM

QUOTE (JRehling @ Mar 30 2008, 06:40 PM) *
....You can't send 500 instruments on one lander. On Earth, you can use 500 instruments on one sample....

This is certainly true, as is the argument that instrument technology evolves. On the other hand, how many instruments do you need to study a sample with in order to understand what is going on there? If the tools available in situ allow you to map the minerals in a specimen with atomic scale resolution, as well as identify isotope ratios, how much more is there to learn by bringing that same specimen back to Earth to run through additional instruments? It seems to me that what is really needed to develop a thorough understanding of Mars geology is sampling over a broad range of terrains, including lots of drilled cores; MSR won't be able to return the mass of rocks which this would involve.



Posted by: vjkane Mar 31 2008, 02:50 PM

We unfortunately seem to be lacking a geochemist on this board who could explain the difference between instruments you can fly on a spacecraft/rover and instruments available in labs.

There are basically two problems with spacecraft instruments. The first is in the preparation of the samples. For example, it is very common to very thinly slice rock samples for study. Routinely done in laboratories. Virtually impossible, as I understand it, to do on a spacecraft. The second problem is the resolution and sensitivity of the instruments you can fit into a spacecraft. For example, rock samples are regularly dated on Earth with great precision by examining subtle differences in ratios of elements. No one has ever figured out a way to duplicate those measurements in situ (except with some proposals that dedicate a lander to essentially one instrument and then accept very large error bars in the results). If a spacecraft finds organics on Mars, is the source simple chemicals from comets or simple single cell organisms a few microns across? Really hard to do with instruments small enough and light enough that you or I could carry them

I'll update an analogy I once heard. What you can fly on a spacecraft with its limits on space, weight, power, and shock (those craft get really knocked around during launch and landing) is to what you can do in a terrestrial lab as a computer you can carry in your pocket (think of smart phones, which really are small computers) to the best super computers available in dedicated facilities with room for thousands of processors, unlimited power, storage, and bandwidth.

Posted by: mcaplinger Mar 31 2008, 03:28 PM

QUOTE (vjkane @ Mar 31 2008, 07:50 AM) *
There are basically two problems with spacecraft instruments. The first is in the preparation of the samples... The second problem is the resolution and sensitivity of the instruments you can fit into a spacecraft.

In my experience, the first may be a problem (though just because thin sections are used traditionally does that mean you have to have them?) but the second is at least partially masked by the fact that few people who do ground-based analysis build instruments at all, and most of those who do don't know much about what it might take make a flyable one. We have certainly come nowhere close to exhausting the capabilities of in situ instruments.

As I said before, this could be a cost-benefit tradeoff if it could be done objectively, but I've never seen an objective analysis, just partial arguments from both sides of the issue and a lot of unsupported philosophy.

I'm concerned that we just don't have enough money to do MSR, so it really doesn't matter how superior it may be in the abstract.

Posted by: edstrick Apr 1 2008, 06:32 AM

"...and I can't think of a single change in Apollo that came out of Surveyor experience..."

Yes. A *lot* of engineers and managers didn't have heart attacks. Surveyor did a lot to protect us from both "Things we didn't know" and "Things we though we knew but weren't so." There were very few of the latter.

"...Apollo returned more than 100 pounds of samples before it returned a single conclusive chunk of anorthosite to pin down the majority composition of the terrae. And this was *years* after in-situ chemical analyses (with an alpha scattering spectrometer) demonstrated a terrae composition "compatible" with an anorthositic gabbro...."

I think it was John Lewis (Lunar and Planetary Lab? / Arizona State?) who looked at the diversity of rock and mineral-grain fragments in Apollo 11 soils, found a distinct non-local population of non-mare feldspar rich rocks, and pronounced them almost certainly highland derived and that the highlands were probably anorthositic. This was in time (I think) for the first Lunar Science Conference: the Apollo 11 Lunar Science Conference. I'd have to dig my copy of "Lunar Science, a Post Apollo View" by Stuart Ross Taylor out to most speedily find the correct reference off net. Probably easier to find it on-net....But I'm lazy.

Posted by: edstrick Apr 1 2008, 06:35 AM

I'd like to see a spacecraft do 1.) Uranium/Lead, 2.) Potassium/Argon, 3.) Rubidium/Strontium 4.) Neodymium/Samarium and 5.) Rheinium/Osmium isotope dating, as well as rare-earth-element geochemical analysis of a rock chip. (Yes, I've left out a few.)

Posted by: djellison Apr 1 2008, 07:39 AM

That's one of the things that Squyres has mentioned in the past iirc. Usually, at the end of a talk, people will ask 'how old are the rocks' - and he replies with something alluding to the fact that the instruments to do that science, no one's figured how to put them in a shoebox yet.

Doug

Posted by: dvandorn Apr 1 2008, 03:24 PM

QUOTE (edstrick @ Apr 1 2008, 01:32 AM) *
I think it was John Lewis (Lunar and Planetary Lab? / Arizona State?) who looked at the diversity of rock and mineral-grain fragments in Apollo 11 soils, found a distinct non-local population of non-mare feldspar rich rocks, and pronounced them almost certainly highland derived and that the highlands were probably anorthositic.

True. But you'd be amazed at the number of theories that floated about which had the feel of last-ditch attempts to either shoot down the magma ocean concept (the only way in which the lighter anorthositic rocks could have separated out and floated to the surface to form a lunar crust) or to maintain some cherished pet theory (that the Moon must be completely chondritic, that it must have never experienced differentiation, or even that it must have once sported real seas and oceans).

It took a combination of orbital sensing (plotting aluminum concentrations from orbit using the J-mission SIM bay spectrometers) and ground truth (sampling a wide variety of anorthositic rocks) to finally prove the existence of an anorthositic original lunar crust, and to banish once and for all the defensive, "no, the Moon must be exactly as I have envisioned it" theories that grasped at more straws than you'll find in a barnyard in order to explain away the feldspar-rich fragments found in mare soils.

That whole episode reminds me a lot of the current state of speculation on Martian geology and planetary genesis. There are literally hundreds of theories out there about Mars which try to explain away ubiquitous observed phenomenah as the results of rare and non-characteristic "special circumstances." As with the resistance to accept an anorthositic crust on Luna, which requires acceptance of a magma ocean, there is still resistance to a Mars that was once warm and wet enough to have generated the water flow features observed there and which leads those who resist to postulate very transitory special circumstances to account for these features. It may require the discovery of, for example, a hidden cache of carbonate rocks to finally pin down the details of Mars' early history -- and it may require far more than "a few" samples to uncover those rocks. And that history.

-the other Doug

Posted by: Mark Adler Apr 9 2008, 12:58 AM

QUOTE (mcaplinger @ Mar 29 2008, 03:17 PM) *
1) I haven't seen any objective evaluation of the cost of sample return versus the cost of in situ measurements. For some large class of measurements, in situ would be far cheaper. Presumably this was the motivation for the "Astrobiology Field Lab". Is there a "sample return mafia" pushing for samples?

Let's assume that all instruments can be brought to Mars, and that we can do the laboratory measurements as well there as here. (Obviously not the case for many measurements, but folk like to argue about those comparisons even though it's not all that relevant to what in my mind is the strong argument for sample returns, which follows.)

Let's say we can do ten such measurement types per rover on multiple locally collected samples. To first order, we can figure that one such set of locally collected samples brought back to Earth will be the cost of, say, five rovers. Then if we want to do 50 such measurements, it's a wash. If we want to do 100 such different measurements, then the sample return is a win. (The Earth measurements will be so much cheaper than the mission, I neglect that cost here, but if you include that cost, the answer will be about the same.) I'd like to know how many different types of analyses were done on the Lunar samples after return. Just in the first three years. I'd wager it's in the thousands.

Now let's look at schedule. This is the real kicker for me, since I'm impatient. Whenever we send an instrument somewhere, it answers some questions, and raises many more new questions. For Mars, we could respond to that with a new in situ instrument at best three opportunities, or 6.5 years later. It happens again, another 6.5 years. And so on. The pace of discovery can be excruciatingly slow, even if you're lucky enough to have something like a Mars Program that keeps sending things there. (I've been through a few of these cycles, and it can really wear you down.)

However, if you have samples here, you do a measurement. It raises questions. You do a new experiment months or weeks later in your own lab or in your colleague's different lab with different equipment. You publish a paper and within a year other labs are answering more questions you raised. While you're waiting for the next Mars in situ mission to be developed and flown, our knowledge of Mars has been completely revolutionized by the equivalent of dozens of in situ missions. The cycle time of discovery is one to two orders of magnitude faster.

So in my mind the strongest arguments for Mars sample return are simply cost and schedule. Sample return is much more cost effective and much more schedule efficient for extensive laboratory investigations than sending in situ instruments to Mars. Even if I completely set aside the issues of packaging entire Earth laboratories in a shoe box, and even if I completely set aside the continuing improvement in the capabilities of Earth laboratories and their application to already collected samples.

Posted by: dburt Apr 9 2008, 02:58 AM

QUOTE (dvandorn @ Apr 1 2008, 08:24 AM) *
...That whole episode reminds me a lot of the current state of speculation on Martian geology and planetary genesis. There are literally hundreds of theories out there about Mars which try to explain away ubiquitous observed phenomenah as the results of rare and non-characteristic "special circumstances." As with the resistance to accept an anorthositic crust on Luna, which requires acceptance of a magma ocean, there is still resistance to a Mars that was once warm and wet enough to have generated the water flow features observed there and which leads those who resist to postulate very transitory special circumstances to account for these features. It may require the discovery of, for example, a hidden cache of carbonate rocks to finally pin down the details of Mars' early history -- and it may require far more than "a few" samples to uncover those rocks. And that history.
-the other Doug

OD, nice history of resistance to the lunar magma ocean hypothesis, but might you have the "warm, wet" Mars argument slightly backwards? After all, was early Mars ever much bigger or closer to the Sun than it is now? Could early Mars (except for abundant ice and an atmosphere) have been more like the Moon than most here prefer to envision it, in that all of those craters we see ("ubiquitous observed phenomena") have something fundamental to do with its history (including rock layering, spherules, water flow channels, crater-filling lakes, subsurface clays, abundant salts, and so on)? Did the LHB (a.k.a. "lunar cataclysm") affect Mars, at the same time as it apparently affected the Moon, Earth, Venus, and Mercury? Would such a "hot" bombardment event tapering off at about 3.8 Ga qualify as your "rare and non-characteristic 'special circumstance'" (analogous to the special circumstance that appears to have, e.g., formed the Moon or killed off the dinosaurs)? Just another hypothesis, already discussed in other posts and publications. By all means, Mars Sample Return!

-- HDP Don

Posted by: mcaplinger Apr 9 2008, 03:12 AM

QUOTE (Mark Adler @ Apr 8 2008, 05:58 PM) *
I'd like to know how many different types of analyses were done on the Lunar samples after return. Just in the first three years. I'd wager it's in the thousands.

I'd bet that there were less than a dozen critical measurements made (age dating and isotopic abundance stuff, primarily), and a whole bunch of essentially trivial and unimportant ones. But I'm not a geologist.
QUOTE
I've been through a few of these cycles, and it can really wear you down.

I've been doing pretty much nothing but Mars stuff for twenty years, and I, perhaps more optimistically, view it as job security. rolleyes.gif
QUOTE
So in my mind the strongest arguments for Mars sample return are simply cost and schedule.

I think you make a very good argument, but I think to really do the tradeoff you have to have a better idea of the kinds of measurements you want to make at a given time and how best to make them. It's often hard to sell big expenditures without knowing what you hope to learn more specifically. It would be more clear-cut if sample return could be done for the cost of, say, 3-4 rover missions, instead of the current estimates, which are in the tens at least.

Posted by: ElkGroveDan Apr 9 2008, 04:13 AM

Has anyone studied the costs and feasibility of putting testing equipment in orbit around Mars vs. all the complications of atmospheric entry and landing? I would venture that you could put more equipment and larger equipment and more fragile equipment into orbit in some kind of automated Mars lab than you ever could land on the surface. The sample retrieval then becomes one of merely getting the sand and rocks up to a defined orbit and nothing more. It would have the benefit of sample analysis from multiple locations at a much smaller cost than either multiple sample returns or multiple rover/lander-labs.

Just shooting from my armchair here, though Mark makes a real good case for Earth sample return.

Posted by: elakdawalla Apr 9 2008, 05:15 AM

I know that a case has been made that a human mission to Mars might be justified even if you never landed the humans on the surface. They could hang out in their pressurized, non-dusty, climate-controlled station in orbit (or on Phobos) and, without the hassle of lengthy two-way light-times, or the risk, complexity, and cost of landing and eventually taking off again, they could joystick vehicles across the surface, retrieve samples for analysis, etc. But I seriously doubt that an early human mission to Mars will include more than a few "shoebox-sized" pieces of science equipment, so that doesn't really solve the problem we're discussing here.

--Emily

Posted by: Stephen Apr 9 2008, 11:28 AM

QUOTE (Mark Adler @ Apr 9 2008, 10:58 AM) *
So in my mind the strongest arguments for Mars sample return are simply cost and schedule. Sample return is much more cost effective and much more schedule efficient for extensive laboratory investigations than sending in situ instruments to Mars. Even if I completely set aside the issues of packaging entire Earth laboratories in a shoe box, and even if I completely set aside the continuing improvement in the capabilities of Earth laboratories and their application to already collected samples.

"Cost effective"? Well, I guess that all depends on whether putting a large number of eggs into one rather expensive basket can be said to be"cost effective"!

Some on this thread seem to be expecting a Rolls-Royce mission. For example, http://www.unmannedspaceflight.com/index.php?showtopic=2570&view=findpost&p=109765 "I'd say the right architecture would be to drop landers onto several top sites with the capability of blasting their samples into orbit. The number of samples so launched may exceed the capacity of the return vehicle to return. Let's say five samples were launched into Mars orbit, with the choice perhaps made of which three should be sent back to Earth."

If each of those landers were carrying a rover the size of the MSL or ExoMars ones (as others on this thread seem to have in mind) then on the face of it we're talking about multiple launch vehicles just to get to the sample collector missions to Mars. As far as I can discover NASA itself is, at least at present, only envisaging a single lander and a single rover. (Just as nobody seems to be suggesting there will ever be an MSR 2.)

In any case, if NASA didn't have the money to send 2 MSLs in 2009 what are the odds it will have enough to send 3+ in 2018 (or whenever)? Without the money then unless Congress and the president suddenly become more generous than they seem to be at the moment (see http://martianchronicles.files.wordpress.com/2008/04/5yearbudget_sm.png which Ryan Anderson mentioned over on http://martianchronicles.wordpress.com/ site) it will surely only be able to do so by cannibalising other areas of its Mars program (as indeed some at the recent MEPAG panel foresaw; see below); and maybe even other non-Mars unmanned missions, especially flagship ones.

IMHO MSR will be lucky to get off the ground by 2018, let alone with multiple rovers. According to the Science article that http://www.unmannedspaceflight.com/index.php?showtopic=2570&st=100&p=110146&#entry110146 back on February 29 on the MEPAG panel "[e]arly estimates put the overall cost of such an ambitious mission at $5 billion to $6 billion". Given that new technology especially for the sample return part of the mission will have to be developed, then given the given past blowouts in cost for such things (eg MSL) I will not be surprised to find the cost will be more like $8-10+ billion dollars by the time the thing actually flies.

Even $6 billion dollars is an awful lot of eggs to be committing to a single basket. If $1-2 billion dollars is reckoned as the cost of a typical NASA flagship mission then that $5-6 billion represents 3+ flagships all rolled up into one, albeit one flying at least two missions (a sample collector and sample retriever/return). NASA will doubtless be under enormous pressure to minimise the costs, not just from the usual budget cutters in Congress but maybe also from some of its own engineers and scientists who will fear that the MSR will become the unmanned equivalent of the space shuttle and the ISS: a project that will suck funding from (in this case: other) unmanned missions, especially those of the flagship class. Multiple rovers will doubtless be among the first things jettisoned to lighten the load and reduce the cost.

I mention that because the news gets worse. In what I presume to be http://www.sciencemag.org/cgi/content/full/319/5867/1174 there is a rather sobering diagram summarising NASA's likely Mars missions for 2010-2020. Of the 5 mission opportunities over that period, two are for MSR (2018 and 2020), one has no mission at all (2011), one is reserved for the next Scout mission (2013), and the fifth is for either the Astrobiological Field Lab or 2 midsize rovers.

In other words, the shifting of the next Scout mission from 2011 to 2013 coupled with the bringing forward of MSR to 2018 has meant if the MSR lander does fly in the 2018 slot there will now be just one other US Mars mission between MSL in 2009 and MSR in 2018. Where before three missions (MSO, AFL, and the mid-sized rovers) were competing for at least two slots those same three are competing for one; and already one of them appears to have lost out judging from that diagram: MSO.

Back last year http://mepag.jpl.nasa.gov/Announcements/Stern_MEPAG_Summary.pdf when MEPAG asked him "if there were one strategic mission opportunity between the
2011 Scout and MSR, would the Mars community choose MSO...Dr. Stern said he would request from MEPAG an analysis of the issues".

As the Science article goes on to point out (and vikane reported previously) that may not be the end of the bad news. "The group determined that NASA would have to cancel everything after MSL--including the 2013 Scout and the 2016 missions--to fly a sample return by the second half of the next decade."

To have no US Mars mission of ANY kind launched after 2009 until 2018 (when the first half of the MSR goes up) would surely be a very heavy price to pay to have a few pounds of rock conveyed back from one particular part of Mars. If MSR does end up being the lone survivor then if for any reason the MSR mission itself fails it will be the 1980s all over again: a decade lost to Mars exploration followed by an expensive all-eggs-in-one-basket mission which tanked.

Is the MSR truly that vital a mission?

I notice that losing the MSO in particular is potentially self-defeating for the MSR project itself. Without MSO then unless the MSR also contains an element which stays in orbit to act as a telecommunications relay (or alternately NASA revives the Mars Telecommunications Orbiter as a separate mission) the MSR rover will be reliant on direct Earth communications and on a fleet of aging orbiters (MRO, the youngest, will by then be well over a decade old).

Finally a query. Do the rovers which get sent to MSR collectors really need to be MSL/ExoMars ones? Could upgraded MERs do the same job, perhaps using some of the MSL technology? I mention that for two reasons:

* For those who want multiple rovers, multiple MER-class ones may be more achievable cost-wise than multiple ones of the MSL-class sort.

* I understand that currently there is a world-wide plutonium shortage that will take some time to redress. "After MSL launches, we're pretty much out of plutonium," http://www.space.com/news/080306-nasa-plutonium-shortage-fin.html. Even Russia is apparently down to its last 10 kilograms. Unless and until that shortage is addressed there may not be enough for even one MSR rover. Which means solar power would need to be used which in turn will weigh against large rovers like MSL ones (as well, of course, as reducing the parts of Mars and the times of year a rover of any sort can rove in, which in turn will doubtless impact on the chances of finding the kinds of results many people seem to expect from such a mission).

======
Stephen

Posted by: algorimancer Apr 9 2008, 05:23 PM

The more I contemplate the cost versus benefits, the more inclined I become to drop MSR indefinitely in favor of multiple rover missions. For that matter, fond as I am of Mars exploration, post-MSL I would be inclined to trade any 2-3 Mars rover missions for 1 non-Mars rover. Places like Ceres, Vesta, Europa, Callisto, Ganymede, Titan, and Triton could each use one or more rover missions, though personally I would put Europa and Titan at the head of the list, closely followed by Ceres. Ceres is likely the cheapest option; planning a Ceres rover to arrive in time to be supported by the Dawn orbiter might just be a heck of a good idea.

Posted by: Drkskywxlt Apr 10 2008, 02:15 AM

Is having MSR a necessary prerequisite for manned exploration of Mars? If Mars gets put back into the Exploration program, there will surely need to be unmanned precursor missions to test equipment...ISRU, etc. A manned mission would surely bring back tens if not hundreds (?) of pounds of samples...could we just not skip MSR and push stronger towards manned exploration? If MSR is looking at only bringing back 1-10lbs for $5-10 billion, would it not be just as cost effective to bring back 100+ lbs for $100 billion?

Posted by: JRehling Apr 10 2008, 06:43 AM

[...]

Posted by: dburt Apr 10 2008, 08:24 PM

There's obviously a trade-off. The rover (mobile) or in-situ (e.g., orbital or on-the-ground) lab approach yields lots of imprecise, necessarily ambiguous data from a handful of instruments for a large number of sites or samples. People here, including me, love that the rovers provide superb imaging (i.e., geological context) for each site. The MSR approach yields wonderful, incredibly precise, incredibly detailed geochemical, isotopic, microscopic, mineralogic, crystallographic, etc. data (independently confirmed at multiple laboratories) on a relatively small number of samples, whose geological context may be less well constrained. Given severely limited budgets, we have to choose. If we choose the MSR approach, we have to be super-careful about geological context.

My conceptual problem - I'm not sure that 20 rovers, imaging and crudely analyzing various occurrences of cross-bedded salty fines and spherules, would unambiguously tell us much more than we know now after imaging and analyzing such rocks at 2 sites (and, in the case of the respective MER teams, coming up with completely different interpretations). If each rover studied different rocks, that would obviously be ideal. That ideal is, however, difficult to achieve when engineering constraints restrict landing sites largely to equatorial flat areas, whose surfaces tend to be dominated by deposition/erosion via late impacts and the wind. Geologists long to study more challenging features such as "young gullies" formed only on steep slopes and the layering exposed in steep canyon or crater walls. Can the present generation of rovers, however long-lived, ever satisfy that longing?

-- HDP Don

Posted by: vjkane Apr 10 2008, 10:58 PM

UNNECESSARY QUOTING REMOVED

Don, excellent arguments, and I believe those that the Mars community (you may be one of them!) are making. Spacecraft instruments simply are crude, and there's a limit to the finess of the of hypotheses you can test with them. The the question is, are we willing to spend $3-5B for those answers? And do we know enough yet to know where to send that one sample mission?

Also, remember that there are four separate craft that must work: Lander, rover, ascent vehicle, Mars orbiter/Earth return craft. The level of risk for this mission will always be high.

The scientist in me wants samples. The mission manager worries about the impact on the rest of the program and the consequences of failure.

Posted by: dburt Apr 11 2008, 03:50 AM

QUOTE (vjkane @ Apr 10 2008, 03:58 PM) *
..The the question is, are we willing to spend $3-5B for those answers? And do we know enough yet to know where to send that one sample mission?
Also, remember that there are four separate craft that must work: Lander, rover, ascent vehicle, Mars orbiter/Earth return craft. The level of risk for this mission will always be high...

Great points. Vicarious exploration via imaging rovers (and to a lesser extent, via orbiters) is certainly personally addictive, scientifically rewarding, and less risky and less expensive than MSR. Unfortunately, the results may always be ambiguous (as in any scientific investigation), owing to instrument limitations. The undeniable emotional appeal of MSR (to me at least) is to remove some of that ambiguity via unlimited instrumentation, a hope that may be somewhat unrealistic, given the history of prior investigations. The cost and risk may also be unacceptably high, as you point out.

Where and what to sample might be the most difficult choice of all, given the large number of questions that need answering (e.g., just off the top of my head, modern life? if so, where? past life? if so, where? past oceans and lakes? nature of past sedimentary deposits? past warm water carbonates? past sedimentary evaporites? past eolian rocks and desert oases? past acid seas or groundwaters? past hot springs? past hydrothermal or igneous ore deposits? past gossans (via weathering of sulfides)? past surface weathering to clays? clay oxidation? modern brines or meltwaters? modern soil and dust mineralogy? salt mineralogy? states of salt hydration? salt efflorescence? salt leaching by frost? types of volcanism? types of igneous rocks and their origin? types of glacial deposits? past climate history revealed in polar layered deposits? types of polar ices, including clathrates? impact-related spherules? impact melts and metamorphism? impact surge deposits near rampart craters or elsewhere? surface peroxides or super oxides? surface silica coatings? desert varnish or caliche analogs? dangers to potential colonists? resources for potential colonists? etc. etc.).

-- HDP Don

Posted by: imipak Apr 11 2008, 05:44 PM

QUOTE (dburt @ Apr 11 2008, 03:50 AM) *
Where and what to sample might be the most difficult choice of all, given the large number of questions that need answering [...]


Or, to make a virtue of what is increasingly looking like necessity: the chances of an MSR from the most interesting (say) 0.1% of the accessible surface are greatly improved by a prolonged remote sensing campaign over several more decades - beyond 2020.

The other way to cut the Gordian knot is simple: more money! What struck me about the http://www.planetary.org/image/5yearbudget.jpg is the arbitrary whims with which the powers that be seem to give and then take away. The 2010 figure's gone from $1200m to $600m to $300m in three successive years. Who knows, if this particular bunch of congresscritters can decide to slash the budget by that extent, in a year or two (or five) another selection (or the same ones!) might equally quadruple the budget in the same way?

Posted by: gndonald Apr 14 2008, 03:23 PM

QUOTE (elakdawalla @ Apr 9 2008, 01:15 PM) *
I know that a case has been made that a human mission to Mars might be justified even if you never landed the humans on the surface. They could hang out in their pressurized, non-dusty, climate-controlled station in orbit (or on Phobos) and, without the hassle of lengthy two-way light-times, or the risk, complexity, and cost of landing and eventually taking off again, they could joystick vehicles across the surface, retrieve samples for analysis, etc. But I seriously doubt that an early human mission to Mars will include more than a few "shoebox-sized" pieces of science equipment, so that doesn't really solve the problem we're discussing here.

--Emily


Many of the 1960's Mars Flyby plans were built around just that concept, an unmanned lander would collect rock/atmosphere samples which would then be analyzed by the astronauts on the return portion of the flight.

On the subject of studying the history of the Martian climate the Altair VI blog ran an article on a proposal to bring a sample of the South Pole icecap back to Earth for study (See: http://altairvi.blogspot.com/2008/04/mars-polar-ice-sample-return-1976-1977.html).

Posted by: Mark Adler Apr 14 2008, 06:35 PM

QUOTE (mcaplinger @ Apr 8 2008, 07:12 PM) *
It would be more clear-cut if sample return could be done for the cost of, say, 3-4 rover missions, instead of the current estimates, which are in the tens at least.

I'm not sure you're taking into account the cost of the latest rover mission. Either that, or you have much larger estimates for MSR than I have seen.

In any case, I am not proposing that we drop all in situ missions and do MSR exclusively. The downside of MSR's is that you invest a great deal of resources in a very small number of sites on Mars. We need to continue the in situ missions in order to cover more sites on Mars, and help us better decide which of those sites are worthy of the MSR investments.

Folk here are wondering why we should even be talking about MSR, since there's obviously no way we'll ever be able to afford it, or if we can afford it, it would hijack the entire program at great risk with the potential of no return (so to speak).

I am not assuming no risk. I am assuming that there will be more than one MSR. If parts of the first attempt fail, then we learn and try again. That is the nature of this business. It is not for the faint of heart.

I am thinking on the 100-year time scale, considering what is the most effective way to explore Mars. In my mind, several sample returns from Mars, say on the order of ten, would be much, much more efficient than a pure orbital and in situ program. There are likely questions we wouldn't be able to answer definitively at all with only a century of in situ work. The life question comes to mind.

As for affordability, MSR can be spread out over multiple opportunities, and could and must coexist with other mission types for the reasons mentioned above. MSR objectives can be split into sampling, ascent, and return missions (requiring both a surface and an orbital rendezvous). That kind of split also has the benefit of spreading the risk, and allowing for more flexible program planning for the introduction of other missions as well as in situ and orbital objectives added to those MSR components.

Some argue that we do not yet know enough to decide where to send MSR. If we thought that there would only be one MSR, ever, for all eternity, then I'd agree. However many science groups have discussed this issue, and we certainly know several places today to send the first MSR, for which those samples would increase our knowledge of Mars manyfold. The results would further instruct the planning for future orbiter, in situ, and sample return missions.

I won't try to do the $ calculations here (since that's fraught with peril, and no one agrees on the numbers anyway). However I think that to first order, a scientifically-rich combined orbital, in-situ, sample return Mars program with about one sample returned per decade could be maintained for on the order of (fy08) $800M a year. Not all of that has to come from the US, and probably wouldn't.

The question of whether such a program would remain sufficiently important in the minds of world policy makers to justify that investment, I have no idea. But that's their job, not mine.

Posted by: nprev Apr 14 2008, 06:47 PM

At the risk of catching a lot of arrows, I think HDP Don made an excellent point that argues against MSR: What should we spend 5 or 6 billion dollars on to return?

Mars is increasingly appearing far more diverse than originally thought when MSR was first conceived. How in the world do you prioritize potential targets? I can't see any single site capable of satisfying the needs of all stakeholders (and there are a whole bunch), which implies requirement creep, possibly to the point of extinction. It'll be a project manager's nightmare.

A manned mission, on the other hand, has to meet one overriding contraint: the site has to be safe for the crew to ingress & egress. This would tend to cut down on community infighting. Moreover, as others have pointed out, the quantity of samples returned would be MUCH larger then MSR could provide, and with any luck also offer some regional diversity (as we saw at Gusev; Home Plate is surrounded by locally typical terrain, and it was a relatively small traverse from the landing site.)

Unless there's a really cheap & much less risky way to do it, I just don't see what MSR can offer for its price beyond the long shot of finding a living native Martian organism. No current concept can provide anything like a representative area survey in terms of tangible payload return, and frankly the MERs have shown that in situ remote sensing is much more effective in this regard.

Posted by: Stephen Apr 15 2008, 08:21 AM

QUOTE (Mark Adler @ Apr 15 2008, 04:35 AM) *
I won't try to do the $ calculations here (since that's fraught with peril, and no one agrees on the numbers anyway). However I think that to first order, a scientifically-rich combined orbital, in-situ, sample return Mars program with about one sample returned per decade could be maintained for on the order of (fy08) $800M a year. Not all of that has to come from the US, and probably wouldn't.

$800 million/year over 10 years == $8 billion

Over a 10 year period there are approvimately 5 Mars launch opportunities. If we assume one mission per opportunity, that means that of that $8 billion you'd be spending $1.6 billion per opportunity. Given that an MSR requires 2 launch opportunities that would roughly give it $3 billion over that 10 years.

Which on the face of it is not bad. The trouble is can an MSR be done for $3 billion, especially the first one?

I dunno, but if you want a comparison here is what Cassini cost (taken from http://saturn.jpl.nasa.gov/faq/mission.cfm).

What does the Cassini-Huygens mission cost?

The total cost of the Cassini-Huygens mission is about $3.26 billion, including $1.4 billion for pre-launch development, $704 million for mission operations, $54 million for tracking and $422 million for the launch vehicle. The U.S. contributed $ 2.6 billion, the European Space Agency $500 million and the Italian Space Agency $160 million.

These figures are from the press kit, "The Jupiter Millennium Mission," which was prepared in October 2000. You can see it at http://www.jpl.nasa.gov/news/press_kits.cfm, where you can also find the press kit that was prepared for the launch in 1997.


Personally, I cannot see an MSR mission costing less than Cassini, especially given that the MSR will involve at least:

* two Earth launch vehiclee
* two landers (or, more likely, one Mars lander and one Earth recovery capsule). Note that this assumes the rover and the Martian launch vehicle arrive on Mars in the same lander. If they don't (or can't) then an extra lander will be needed.
* one rover
* one Martian launch vehicle
* one in situ fueling apparatus for the Martian launch vehicle (if said vehicle does not come pre-fuelled; this can be dispensed with if it does, although the pre-fueled sort would, of course, increase the size and weight of the Martian launch vehicle as flown from Earth)
* two (or maybe three) cruise stages (two for the flights to Mars and maybe a separate one to send the samples et al back to Earth unless the second Mars one is reused)
* an Earth entry vehicle (although this may be incorporated into the Earth lander)
* Optional extra for first launch: an orbiting telecommunications relay for rover & Martian launch vehicle ground operations

For those who have hopes of international partners defraying part--and presumably a substantial part--of the cost I notice that in Cassini's case American taxpayers are paying for nearly 80% of the mission. If that were so for that $800 million/year Mars program that would mean the US would still need to fork out about $640 million a year.

(Of course, if the international partners aren't involved in the entire program only in particular missions, or parts if particular missions then there may be some years where the US has to fork out the entirety of that $800 million.)

BTW, note that $1.422 billion + $710 million + $54 million + $422 million + $500 million + $160 million == $3.27 billion

That is, most of the upfront cost and ongoing operational costs were (and are) apparently being borne by NASA.
======
Stephen

Posted by: Stephen Apr 15 2008, 11:10 AM

QUOTE (Mark Adler @ Apr 15 2008, 04:35 AM) *
If we thought that there would only be one MSR, ever, for all eternity, then I'd agree.

With all due respect, that may be exactly what will happen. sad.gif

How many (unmanned) Lunar Sample Return missions has America ever launched? Once the Apollo program was lofted into political orbit courtesy of JFK there was no need to send any. The manned missions were expected to handle the sample returning part.

That particular precedent suggests that the window of opportunity for NASA MSRs will only last until manned missions to Mars find their way onto NASA's launching schedules (as opposed to the mere vague promise we have at the moment of having some manned missions to the Red Planet at some unspecified point down the track).

Moreover the window will probably close some years before the first manned mission is actually sent because those will be the years NASA will be wanting to give priority to sending unmanned missions which will support the manned ones. Sample returns will probably find themselves at the end of the queue unless they can be justified in a manned context. (Eg sending rovers on several years ahead to collect samples for the astronauts to retrieve. But that isn't quite the same thing as a fully unmanned MSR.)

For example, if NASA sends its first manned missions in the mid to late 2030s then even at a rate of one MSR per decade it's unlikely there will be more than 1 MSR because at some point in the mid to late 2020s, or early 2030s at the latest, the "window" will close as NASA begins ramping itself up for the manned missions. If the first goes by 2018 then by hurrying the second you might squeeze in two, especially if parts of the first (eg the rover) could be reused and/or if parts of the MSR (eg vehicle frames, Martian launch vehicles) could be standardised so that the proverbial wheel did not have to be reinvented for each mission, and also reducing the lead time. But sending the MSRs to the same part of Mars simply to cut costs and get a second in may not go down well.

And of course that is all assuming the first part of the the first MSR leaves in 2018. The longer the first gets delayed the less likely there will be many more. Or even any more.

Then there's the growing competition for a slice of the NASA funding pie from other high-priced unmanned missions in the decades to come, especially into the outer solar system. NASA is slowly accumulating a growing number of increasingly expensive committments--or at least expectations for--flagship missions to places like Titan and Europa. It seems fair to say that at least two contenders are already an inevitability: a Europan orbiter and a Titan/Enceladus mission; and one can foresee at least two more in the years beyond 2030: a mission to probe below the ice of Europa into its putative ocean (most seem to be expecting an Europan orbiter will confirm such an ocean) and a Neptune orbiter;and maybe a Titan rover/balloon also if the next Saturnian mission isn't such a one. Already NASA is having to pare back Mars funding to pay for its next outer planets flagship mission (which in turn may force the MSR to steal funds from other Mars missions like the AFL).

Unless NASA's overall funding improves that sort of thing is only likely to grow worse. What will probably happen is that some missions will get pushed back to pay for others. The problem MSR missions face is that if they get pushed back far enough sooner or later they will collide with any American manned program to Mars which does eventuate.

My own guesstimate is that if the first MSR does start in 2018, then the next is not likely until around the mid to late 2030s, with maybe a third some time in the early to mid 2050s. That is, 15-20 years between MSRs. Under that scenario, however, to have a second would require the manned missions be pushed back to the 2050s while a third MSR would only occur if manned missions were pushed all the way back to the 2060s or later, which frankly would be a tragedy. (In fact if it did happen one can almost predict the likely landing date of the first mission now: July 20, 2069!)
======
Stephen

Posted by: AndyG Apr 15 2008, 01:31 PM

QUOTE (Stephen @ Apr 15 2008, 12:10 PM) *
...July 20, 2069!)

Much as I love robots, that is too depressing.

Will they take 106-year olds?

Andy

Posted by: Mark Adler Apr 16 2008, 05:43 AM

QUOTE (Stephen @ Apr 15 2008, 12:21 AM) *
Given that an MSR requires 2 launch opportunities that would roughly give it $3 billion over that 10 years.

As I mentioned in my post, I was considering using three opportunities for one MSR, not two. Rover, ascent, and return orbiter. In a decade you get that plus 1.6 more quite well-funded (i.e. not Scout) non-MSR missions and the option of additional payloads on the MSR elements. Doing the arithmetic correctly (26 months per opportunity) results in about $5.2B per MSR.

That's not quite right, since there are other program costs besides the missions, but to first order we're talking around $5B per spread-out MSR, not $3B. There are more cost-efficient ways to do MSR when profile is not an issue, but profile is always an issue.

Posted by: PDP8E Jul 10 2008, 11:34 PM

announcement for the date for their Mars SAR Mission -- 2018

http://news.bbc.co.uk/2/hi/science/nature/7500371.stm

cheers

Posted by: John Whitehead Jul 11 2008, 12:33 AM

full inline quote removed - Admin

Nice to see that the powers that be are still pushing for MSR to happen. However the conceptual video depicts a mere "grab-and-go" mission that the Mars science community is violently opposed to (versus careful sample selection). Perhaps worse (and my own pet peeve), the Mars ascent vehicle is depicted as 2 stages built according to satellite-type propulsion methodology. When is the Mars community as a whole going to appreciate that the necessary miniature launch vehicle needs about a decade of aggressive new rocket technology development. Let's see, 2018 minus a decade is today, but (for example) NASA's Mars Technology Program this year is barely breathing.

Yes I know it's just a marketing video but it reinforces the ingrained prejudice that all planetary missions can be done using satellite parts!
John W.

Posted by: djellison Jul 11 2008, 06:18 AM

That ESA animation has been doing the rounds for years - I would read exactly nothing into it, especially when Europe is far more likely to build the return-leg orbiting component.

Doug

Posted by: PDP8E Jul 11 2008, 06:31 PM

My favourite nonsense SAR image is this (lifted from nasa site)



there is so much wrong with this artwork.

1) where is the descent stage? (MSL??)
2) the ramp goes to where?? on the corresponding point on the ascent stage
3) check out the 'arm' on the launch pad
4) the mid 90's version of Sojourner hanging around on a cliff
5) 'another rover' on the far hillside (where is that descent stage?)
6) zero aerodynamic considerations on the ascent stage (this thing still has to punch a fast hole in the thin atmosphere)

Doug, you should hold a Mars Sar artwork contest on the site and give the winners to NASA!

cheers



Posted by: stevesliva Jul 11 2008, 07:48 PM

QUOTE (PDP8E @ Jul 11 2008, 02:31 PM) *
6) zero aerodynamic considerations on the ascent stage (this thing still has to punch a fast hole in the thin atmosphere)

I missed that one. Note to self: Mars has an atmosphere.

And what taketh away, giveth. It's hard enough to slow down during EDL.

Posted by: Mariner9 Jul 11 2008, 09:34 PM

I was also surprised by that 2018 date, but the more I thought about it the more it made sense.

History suggests that whatever date you propose for a mission like this almost inevitably slides, for both technical and political reasons.

So, why propse a more technically reasonable date like 2020, or 2022, if it is only going to get slipped by the political process into 2024?

Seems like a reasonable gambit to propose 2018, and then have to suffer a slip into 2020 or 2022, which is the soonest you can be ready anyway.


Posted by: John Whitehead Jul 12 2008, 01:31 PM

Hi again,
Re the past couple days of comments above, OK fair enough to not read anything into artist conceptions, and fair enough to set a date that may later slip.

The source document underlying the July 10 news item is available from the Mars Exploration Program Analysis Group at http://mepag.jpl.nasa.gov. Click MEPAG Analysis Reports, then scroll all the way down to the bottom, to download the Preliminary Planning for an International Mars Sample Return Mission, Report of the iMARS (International Mars Architecture for the Return of Samples) Working Group. This document has 31 authors (the Working Group) and is dated 2008Jun1.

The Mars Ascent Vehicle (MAV) is listed as the second item in the table on page 21 (p. 25 of the pdf). The third column, "Technology Development Needed," lists 3 items for the MAV as follows.
1. Propellant and materials for long-duration storage and performance in Mars environment.
2. Launch from low-mass landed platform.
3. Low-mass avionics.

"Propellant and materials" development? Strangely, no mention of the need to create and design and build a miniature launch vehicle!

The only place in the text I could find mention of the MAV is on page 29 (p 33 of the pdf) which merely says there needs to be a MAV. Other items for the mission are discussed in more detail.

The very next page shows a schedule for technology development (Figure 5). Major headings are Orbiter Technology, Lander Technology, and SRF Technology (Sample Receiving Facility in Texas). The MAV should logically be one of the major headings, but it is lumped in as a mere item within Lander Technology.

Based on the iMARS report, I again submit that the MAV challenge is way underestimated. There simply is no community of people who have experience building miniature launch vehicles, which is consistent with a lack of lobbying for recognition and funding of the MAV problem.

John W.

Posted by: nprev Jul 12 2008, 01:41 PM

I believe somebody mentioned the idea of having another look at the mid-80s US ASAT missile, which was launched from an F-15; might be a good idea as a starting point.

Only as a starting point, though, and probably only as a case study in compact solid booster design. I agree with you, John; this is a formidable problem that had better not be underestimated. The ASAT payload certainly wasn't designed to do anything but find & hit a target, and a MAV needs to be a whole hell of a lot smarter & adaptive for this stunt to have a prayer of working.

Posted by: djellison Jul 12 2008, 01:41 PM

QUOTE (John Whitehead @ Jul 12 2008, 02:31 PM) *
There simply is no community of people who have experience building miniature launch vehicles,


http://en.wikipedia.org/wiki/RIM-161_Standard_missile_3
http://en.wikipedia.org/wiki/AGM-48_Skybolt
http://en.wikipedia.org/wiki/MGM-140_ATACMS

There is a large community who've been building vehicles of an approximately similar performance envelope for some time.


Furthermore

http://www.jpl.nasa.gov/releases/2001/release_2001_153.html
http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/11012/34697/01655737.pdf?temp=x
http://www.ingentaconnect.com/content/els/00945765/1999/00000045/00000004/art00148
http://www.esa.int/esaMI/Aurora/SEMRW7A5QCE_0.html - especially http://esamultimedia.esa.int/docs/Aurora/execsummaries/TN_Executive_Summary_PAV_complete.pdf
http://citeseer.ist.psu.edu/385428.html

That's from the first page of putting 'mars ascent vehicle' into google.


Doug

Posted by: mcaplinger Jul 12 2008, 02:00 PM

QUOTE (djellison @ Jul 12 2008, 06:41 AM) *
There is a large community who've been building vehicles of an approximately similar performance envelope for some time.

AFAIK, your examples are not of "of an approximately similar performance envelope". Go back and read post 90 of this thread, and many of John's subsequent posts. ASATs aren't getting into orbit.

Posted by: John Whitehead Jul 12 2008, 02:12 PM

The ASAT missile weighed a ton, more than the lander, MAV, rover, etc. combined (assumed future affordable capability based on the expectation that the 2009 MSL will successfully land almost 1 ton total on Mars).

A popular definition of "space" is expressed in terms of altitude, but achieving orbit is more about velocity. The ASAT missile merely went straight up to about 500-600 km, which needs a very minor fraction of Earth's orbital velocity. Mars orbital velocity is 45 percent of Earth's. The MAV needs to accelerate zero to 9,000 MPH in 5 minutes.

Generally, rocket motors for military missiles have less raw propulsive performance than space motors, because the former have to be cheaper for quantity production, structurally more robust for abuse in the field, etc. We shouldn't pin our hopes on the possibility that something better than existing space propulsion hardware is available from behind the scenes in the military world.

Overall nprev is right that existing technology gives us "only a starting point." The question is when and how and who is going to move forward to develop a MAV? Part of the reason that the aerospace engineering community does not have a cadre of experts who are spooled up to develop a MAV, is that rocket technology development reached diminishing returns circa 1970, and the expertise in the field faded (along with funding cuts). Today's rocket experts implement relatively small evolutionary departures from existing technology.

John

Posted by: djellison Jul 12 2008, 02:32 PM

QUOTE (John Whitehead @ Jul 12 2008, 03:12 PM) *
The question is when and how and who is going to move forward to develop a MAV?


When they get paid to do it, by doing engineering, probably JPL/Ames or similar in colab with industry.

It's a huge challenge - no doubt whatsoever, but I don't really get your point. Where's the cadre of experts for a Titan balloon? Where's the cadre of experts for anything...that we've not actually done yet? The answer.... you get that talent and knowledge by doing it. There's barely the money to build and fly MSL. Given that politics is a banned discussion from this forum - what do you want to talk about.

You didn't say 'There simply is no community of people who have experience building miniature launch vehicles of the exact scope and specification that will be required for MAV'.

We wont have...until we've built an MAV. I'm not going to get into an argument about this ( although it seem you really want one ) - but it's chicken and egg. We didn't have Mars EDL experts till after Viking. We wont have MAV experts till after MSR. Someone needs to write a very big cheque, and the problem will thus be solved. Thats all there is to it.


Doug

Posted by: nprev Jul 12 2008, 02:42 PM

Ironically, I'm not even sure that MAV is the long pole in the tent for MSR; there are a bunch of them. For example, the automated Mars orbit rendezvous, capture, and sample transfer process to the Earth return container seems like it might turn out to be fiendishly complex, and will require extremely robust software with autonomy bordering on AI capabilities.

On the happy side, such a technologically challenging project is just what the doctor ordered for NASA & ESA. As John pointed out, there's been some damping down on rocket development over the last few decades, and thatt's probably true for other disciplines as well since the focus is almost uniformly on staying on time and within budget. The sheer amount of R&D and innovation that will be needed to fly MSR would greatly benefit UMSF overall in the long term, and probably produce a number of significant spin-offs for non-space applications.

Posted by: nprev Jul 12 2008, 02:57 PM

Don't usually double-post, but just had a wild thought: Why can't MSR be deferred until the Orion/Constellation Mars landing architecture is developed?

Rationale here is that it might make more sense to frame MSR as both a critical science mission and a critical test of the future manned Mars landing effort. At some point, there will need to be a realistic test of the crew descent/ascent vehicle; why not fly one with a rover or two that could pick up several hundred kg of samples while executing a nominal manned mission profile? A shakedown cruise of the system seems very desirable in any case.

Big bucks, yes...but also access to a different and much larger pot of money... wink.gif

Posted by: mcaplinger Jul 12 2008, 03:43 PM

QUOTE (nprev @ Jul 12 2008, 07:57 AM) *
...just had a wild thought: Why can't MSR be deferred until the Orion/Constellation Mars landing architecture is developed?

One reason is because Orion may well be dead six months from now. Another is that the engineering problems aren't very similar even if VSE does ultimately end up going to Mars. Think of Apollo compared to Luna 16.

I think the point John is making, and it's an important one which I have little reason to doubt the validity of, is that the MAV will require a great deal more technology development than many in the Mars community seem to be assuming. For this and many other reasons, I am very pessimistic that we will see MSR any time soon.

Posted by: ugordan Jul 12 2008, 04:47 PM

QUOTE (John Whitehead @ Jul 12 2008, 04:12 PM) *
Generally, rocket motors for military missiles have less raw propulsive performance than space motors, because the former have to be cheaper for quantity production, structurally more robust for abuse in the field, etc. We shouldn't pin our hopes on the possibility that something better than existing space propulsion hardware is available from behind the scenes in the military world.

Add to this the fact that all the military missiles I saw listed here are solid propellant ones. I'm fairly certain that if there ever is a MAV developed, it will be liquid fueled. Solid propellant, while easier to handle and make rocket motors with has an inferior specific impulse. This implies a heavy ascent stage and a correspondingly heavy descent stage. We can be sure mass will be the limiting factor as usual so we can pretty much rule out solid motors as feasible.

Posted by: djellison Jul 12 2008, 07:46 PM

- 1.5 The manned vs unmanned debate will be never ending, always heated, and it is not allowed on this forum

Three posts deleted.

Posted by: mcaplinger Jul 12 2008, 11:29 PM

QUOTE (ugordan @ Jul 12 2008, 08:47 AM) *
Solid propellant, while easier to handle and make rocket motors with has an inferior specific impulse.

According to various analyses I've done in the past, the Isp of solids is better than that of monoprop hydrazine and competitive with biprop hydrazine/NTO (in the range of 300 s). Biprop might be a little better, but the advantage is not huge.

More expert opinions welcome. I would love to see a good design for a MAV, but I'm not sure I have seen one yet. The original MiniMAV was very attractive but in hindsight too optimistic.

Posted by: ugordan Jul 13 2008, 10:35 AM

That's interesting. I was under the impression solid propellants have less than 300 s Isp (the figure for Shuttle SRBs is 285 s in vacuum) while hydrazine/NTO is said to have 340 s in vacuum. I'm using vacuum level Isp because Mars' atmosphere is obviously much closer to a vacuum than Earth sea-level pressure.

Then again, the solid fuels I looked at were optimized for rocket strap-on boosters which could be optimized for high thrust rather than high Isp. Don't know, I'm really not an expert.

Posted by: mcaplinger Jul 13 2008, 03:15 PM

Even if the Isps were 285 and 340, that's only a 20% advantage for biprop, which could easily be offset by the mass of tankage, pressurant, plumbing, and thermal control to keep the propellant from freezing. I'd say solids were still viable based on that.

Posted by: ugordan Jul 13 2008, 04:30 PM

It's true that's only 20% in Isp difference. However, for a given desired delta-V, the fuel mass varies with exp(deltaV/(Isp*9.81)). For low target velocities that's similar to the Isp difference. Say you wanted to reach Mars orbital velocity, 3.52 km/s. That amounts to 22% higher prop mass for solids. If you wanted to reach martian escape velocity, 5 km/s the difference becomes 33% which is starting to look more serious. Add into consideration gravity drag and the delta-V needed to reach orbit exceeds that of orbital velocity by at least a few hundred m/s. Mars has one thing going for it regarding gravity drag - lower gravity and less dense atmosphere allowing a more agressive acceleration profile. Then you come back to the thrust of the ascent stage, in which case solids are better.

A 25% increase in mass doesn't seem that high to justify the complexity of liquid propulsion, agreed, but what about the mass required to land the extra 25% mass in the first place? I have a feeling that doesn't scale linearly either. It's a tricky design to optimize indeed.

Posted by: Zvezdichko Jul 13 2008, 04:40 PM

I have always wondered...

What about two separate launches from Earth -one for a lander+MAV and one for an orbiter and entry capsule? What about a single-stage MAV plus unmanned docking in Low Martian Orbit?

Posted by: John Whitehead Jul 13 2008, 05:16 PM

QUOTE (djellison @ Jul 12 2008, 02:32 PM) *
I don't really get your point. Where's the cadre of experts for a Titan balloon?
... you get that talent and knowledge by doing it... Someone needs to write a very big cheque, and the problem will thus be solved. Thats all there is to it.

Hey Doug, hopefully your comments will help me focus better on what I was trying to explain. I think the whole planetary community would agree that a Titan balloon would be entirely about innovation, and I think that planetary scientists and others planning missions do consider Titan balloons to be interesting. My concern is that the MAV rocket problem does not seem to be viewed similarly. Has anyone met a planetary scientist who finds propulsion systems to be interesting?

Innovation is unwelcome in the development of propulsion systems for planetary missions, and the engineering culture is built around the notion of only using what is already proven. Spacecraft organizations treat this sort of work as an automatic process. People working in the space propulsion discipline have been taught by their experience that a new project won't get funded unless they say existing technology will suffice. But the technical problem that exists is not one of obtaining the "exact scope and specification." Launching from Mars to orbit, with a vehicle the size of a person, is far beyond being a variation of previous capability.

I absolutely agree that you get the talent and knowledge by doing it. The Rover Team is a great example of a major technical talent pool being convened and nurtured to do something totally unique to Mars exploration. It took decades to build the team and then create working flight rovers, and my understanding is that it has not been easy to keep the team together. I suspect that building up expertise of a similar magnitude for a similarly specialized purpose is going to be needed for the MAV.

While I too look forward to seeing the big checque written for MSR, the reality is that the Mars Program budget is constrained. If money flowed freely, then robotoc sample return could be a dry run for a human mission, using the full scale hardware. I wouldn't agree that money can solve any defined technical problem, since physical limits do exist. In many engineering endeavors, the primary difficulty is complexity. For the MAV (built small enough for an affordable mission), the primary difficulty is physical limits related to the strength of materials, miniaturization thickness limits, unfavorable cube-square scaling of drag versus mass (similarly heat flux versus mass), and unfavorable scaling for other things like manufacturing precision and the effects of fluid viscosity. Does everyone in the system appreciate that complexity and physical limits present totally different kinds of difficulty?

mcaplinger, thanks for understanding.

John W.

P.S. to ugordan: Despite Mars's thin atmosphere, the ideal acceleration profile starts at about one earth gee, because the effect of drag is greater for tiny vehicles like the MAV needs to be. Solid motors on the scale of interst inherently have ten times the ideal thrust, hence more drag.

P.S. to zvezdichko: Separate launches from Earth as you suggest has been the nominal notion for MSR since the late 1990's, with rendezvous in Mars orbit at 500 km altitude. Even to only reach Mars orbit, a single-state MAV might be more difficult than a 2-stage MAV. I personally think a single-stage MAV is possible with a hard technology push, and desirable for several reasons.

Posted by: dvandorn Jul 13 2008, 05:38 PM

In actuality, I truly don't think the issue is really designing a MAV -- no offense, John, but it's really not that hard to design a rocket that can do the job. You don't need revolutionary new propulsion technologies to get off Mars and into MEO.

The problem is that with most any existing rocket technology, you have to land a very large mass onto Mars to make MSR work. Not as large a mass (or set of masses) as for a manned landing and exploration, but a very large mass, indeed. And the problem is that we've maxed out the amount of mass we can land on Mars with something roughly the mass of MSL. Much heavier and you run smack into the Mach 5 problem that has been discussed here extensively; the mass required for a MAV is large enough that friction with Mars' thin atmosphere isn't enough to slow it to a speed from which rocket braking can take over and reduce it to a landing velocity before the vehicle crashes.

Let's face it, it's probably just not possible to build a MAV powerful enough to do the job and that is yet light enough that it can be landed (even in pieces) with our current ability to do a successful EDL.

So, the EDL challenge would seem to me to be the limiting factor. If we can beat the Mach 5 problem, then it just becomes a matter of spending the money needed to get that mass to Mars in the first place.

-the other Doug

Posted by: John Whitehead Jul 13 2008, 06:09 PM

Yes of course, oDoug. If you define the problem as (1) "accomplish MSR within existing program budgets," then you have to develop a ~100 kg MAV. If you define the proglem as (2) "design MSR around a practical MAV that can be built with existing technology," then you need to develop a bigger EDL system and spend lots more money. To the best of my understanding, such a MAV would mass several tons, i.e. an order of magnitude in mission scale and cost.

Given that mission costs are about 1-2 million dollars per kilogram placed on Mars, it would seem to be worth a hundred million dollars to develop ANY new Mars technology that can make the mission scale 100 kg smaller. However organizations need to grow, so organizations tend to favor the second scenario even when there is very little hope for increasing funding. Is it possible that MSR is caught in a stalemate such that we can't pay for the necessary work to make the mission affordable?

By the way, the Mach 5 problem could be solved by pushing hard on new innovative propulsion technology. Just use better propulsion instead of a parachute from Mach 5 on down.

John W.

Posted by: Zvezdichko Jul 13 2008, 06:32 PM

John - what you suggest has been reviewed. There's no way to fire the thrusters during the hypersonic descent. Imagine driving your car in the center of a hurricane!

Posted by: dvandorn Jul 13 2008, 06:45 PM

I do understand your point, John. The problem with just inventing better rockets to drop the mass from Mach 5 down to zero is that, as the mass of what you're landing goes up, the total amount of its entry velocity that can be shed solely through atmospheric drag becomes less and less. And the more velocity you need to shed using rockets, the more propellant you need to carry, and the less effective drag slowing becomes. It's a vicious circle.

And besides, if you're going Mach 5 and you're a kilometer above the surface, and you have no more than about 30 seconds to remove the remaining velocity, just how many G's would you have to pull to avoid crashing? A 50-G deceleration would probably be outside the limits for Mission Success in any manned or unmanned mission I can imagine, and I can't imagine the required deceleration being much less than that.

If you use chemical rockets, you're going to keep coming up against the isp limits we've already identified as barriers to growth. We need truly revolutionary advances in propulsion technology, not just engineering tweaks of known technologies, to get the performance-to-mass ratios required for an effective MSR, much less for manned landings. IMHO.

If you look at it as a Venn diagram, I'm just afraid that the set that contains what's possible to do with chemical rockets, and the set of the mass of vehicles required for MSR, are sets which do not overlap...

-the other Doug

p.s. -- please bear in mind that I'm qualifying all of this when I say we need an EDL breakthrough for an *effective* MSR. I do not consider spending 15 billion dollars to bring back less than a kilogram of samples to be effective. That's an awful lot of money to return, frankly, far less material than we already have to analyze from Martian meteorites. -dvd

Posted by: djellison Jul 13 2008, 06:47 PM

QUOTE (John Whitehead @ Jul 13 2008, 06:16 PM) *
Has anyone met a planetary scientist who finds propulsion systems to be interesting?


Has anyone met a propulsion engineer who finds mossbauer spectra interesting?



Posted by: PDP8E Jul 13 2008, 08:14 PM

very funny doug!

My hack at the problem...its just a broad outline...please turn flame throwers to idle
There is probably nothing new here, other than independent parallel invention

To do the Mars SAR mission and to bypass the mach 5 problem (not enough atmosphere for heavy landers to decelerate safely)
then it must be a divide and conquer solution.

the spaceships required are

* earth-to-mars vehicle that carries a single return-to-earth vehicle with return fuel
* earth-to-mars vehicle(s) that carry one or more of the 2 required landers

Assemble the fleet in mars orbit (use a circularizing method, aerobrake or engine) fly in formation

The two landers:

* One with the MAV 1stage and launch platform (2000lb of propellant) -- use a tested EDL & a sky crane
* the other: a beefy rover with the MAV 2ndstage (1000lb of propellant), also the sample return container/nosecone -- use a tested EDL & a sky crane

The MAV 1stage lands first.

a few days later the Rover/MAV 2nd-stage lands-- very near the first (2 km?) -- precision landing required

The rover loads a contingency sample into the return container
The rover & second stage set out and find The MAV 1st stage. The MAV stages are mated (both stowed horizontally)
Rover still has access to the sample container (which has the contingency sample locked and loaded)

The rover (sans 2nd stage) goes on a science mission to find the best samples (2-6 week mission, 2-20km )

The Rover comes back and loads the samples

MAV is erected vertically - checkout - launch

Rendevouz with Earth return vehicle - sample container stowed

Leave orbit and head back to earth

Rover continues science studies until it dies

I don't think there is any new or breakthrough science needed here
Just alot of complicated machinery that needs to be robust and elegant.

ok...flame throwers set to stun....


Cheers

Posted by: Zvezdichko Jul 13 2008, 08:25 PM

I think that the biggest problem won't be the anything concerning the landing phase, but the MAV itself. We all know how complex launching a single rocket is with all problems, delays and so on. A MAV (or a mars rocket) has to be fully autonomous and, of course it has to work flawlessly. That's why I suppose that it will be solid-fueled because it's the simplest design and there aren't many options for failure.

I think that the two-launch scenario (an orbiter plus lander) is the best. The orbiter, while waiting for the MAV to arrive may be busy collecting atmospheric samples using aerogell (already tested on Stardust and Genesis). The MAV may be delivered on the surface using a skycrane technique, specially redesigned for this purpose. I can't think of a better idea. Though I know how difficult fully automated docking may be.

Posted by: vjkane Jul 13 2008, 09:04 PM

I suspect that when the failure modes are analyzed that the lander/rover/launchers combination contains the overwhelming portion of the MSR risk. I think that having two sets of lander/rover/launcher should be baseline. If both deliver samples, great. However, if you send one and it fails, then the entire $5-8B is gone.

Posted by: hendric Jul 14 2008, 07:04 AM

Why don't we just land a tank on Mars? It can rove around, picking up interesting samples and loading them into rocket-assisted shells. Once it is ready to launch, it can use a compressed air gun (remember the post-Columbia tests? ) to fire the shells upwards, one at a time. Fill the tank with CO2, heat it up nice and hot, and BLAMMO! Rifling on the barrel handles the guidance task for the first "stage". That's got to be good enough for a dozen or two km of altitude on Mars. Ignoring drag, 300m/s gives you 12km; 500m/s gives you 34km, enough to reduce the atmospheric pressure by 95%. Then, WOOOSH, your rocket boosts you to orbit!

Problem solved!

I CAN HAZ 8BIZZILLION DALLARS NOW?
K TNX

(Sorry, in a goofy mood)

Posted by: John Whitehead Jul 14 2008, 05:14 PM

QUOTE (djellison @ Jul 13 2008, 06:47 PM) *
Has anyone met a propulsion engineer who finds mossbauer spectra interesting?

The rocket guru didn't cower
When confronted with data Mossbauer
She studied for weeks
Spirit's olivine peaks
But who else grooves on MAVs for an hour?

They'd pay for a tiny launch tower
And order propellants for power
But they sought a cheap rocket
Plucked from someone's hip pocket
Their grasp of the MAV didn't wow 'er

Seriously folks, it is too easy for all of us to take the other person's work for granted. But I thought that scientists and mission planners have a strong direct influence on budet decisions that could lead to funding technology for launching off of Mars, while rocket engineers have little or no direct influence on the budget planning process for science. Ideally rocket engineers would have an indirect influence, by creating a 100-kg MAV to leave room on MSR for more science. Yes there are technically valid solutions that permit a heavy MAV, but they all cost more.

Another recent news article:
www.guardian.co.uk/science/2008/jul/14/mars.spaceexploration

Re the latest comment from hendric, the MAV has to be relatively fragile in order to obtain the high ratio of propellant to inert mass, so it would not help to shoot it out of a cannon just to reduce the MAV velocity requirement by 10 percent or so.

John W.

Posted by: JRehling Jul 14 2008, 07:13 PM

[...]

Posted by: JRehling Jul 14 2008, 07:24 PM

[...]

Posted by: dvandorn Jul 14 2008, 07:27 PM

Just exactly how much sample do you expect to return to Earth with a MAV that weighs, grand total with sample container and fuel, 100 kg?

No more than a gram, I would imagine -- and that would be pushing it.

Can I ask exactly what you think we can do with a gram or less of Martian surface materials? And why we would spend a billion dollars (or multiples thereof) for such a miniscule amount?

Just... curious.

-the other Doug

Posted by: djellison Jul 14 2008, 07:34 PM

QUOTE (dvandorn @ Jul 14 2008, 08:27 PM) *
Just exactly how much sample do you expect to return to Earth with a MAV that weighs, grand total with sample container and fuel, 100 kg?


Typical figures quoted are about 1kg

Posted by: SpaceListener Jul 14 2008, 08:04 PM

The MSR mission is very pricely. Why so much difference?

As an example, the most expensive mission to Mars would be for MSL by between 1-2 thousand millions dollars (I don't say billons -> millions millions). And the MSR would be between 3 to 5 times more expensive than MSL with just adding a few hundred of kilograms of weight to the spacecraft in order to return a 1 kg of sample. Well, I too agree that by sending as many in-situ spacecrafts to Mars would yield a better cost-benefit to science. Just a thought

Posted by: PDP8E Jul 15 2008, 12:02 AM

QUOTE (JRehling @ Jul 14 2008, 02:13 PM) *
Does SAR stand for something besides Synthetic Aperature Radar, or is this a typo for MSR?

Hey JR,

SAR is the OLD school 'sample and return' acronym.

It doesn't have a place name attached to it so it can be used for anywhere (moon,mars, asteroid, the antarctic ....)
as opposed to MSR ...

thanks for pointing out the anachronism
rolleyes.gif
My Bad!

Cheers

Posted by: Mariner9 Jul 15 2008, 03:28 AM


The cost of the mission is sure to be a political trouble magnet, no doubt about it. And I'm among those who have doubts about the likelyhood of this all coming to pass.

But, in defense of the benefit of the mission, consider this.

We are rapidly getting into a point of diminishing returns on the Mars unmanned missions. Mars Global Surveyor was a huge step forward in our understanding of the planet, but can anyone reasonably think that we could find another 300 million dollar orbiter to make another quantum leap forward? The next generation of orbiters, MRO, cost more than double that figure at around 700 million.

Same thing with Phoenix. For about 500 million we get a nice little chemistry lab at the north pole. We should learn a lot of good fundamental information, if for no other reason that we have only had a small handful of landers on Mars before this. But fly a second mission of that class, and the ammount you advance your knowledge is somewhat smaller. Do you learn 4 times as much flying 4 more of them? Not likely. I really doubt we will see many more landers like Phoenix.

MSL is a great mission, but in order to advance beyond the MERs, we had to jump in cost from 800 million to 1.9 Billion. Now, to improve on MSL, what next? Do we move up into the 2-3-4 billion dollar range?

So, while there is still a lot we can learn with the in-situ unmanned missions, it starts to cost more and more to advance less and less.

Eventually Mars Sample Return, as expensive as it is, starts to look cost effective in the 'bang for your buck' department.


Posted by: nprev Jul 15 2008, 03:46 AM

Hmm. Food for thought, Mariner.

The only real heartburn from a data return standpoint I have is that MSR would bring us a sample from one, count it, one, very small area of Mars. The planet's geological diversity is really becoming apparent (esp. from MRO & MEX), so much so that I wonder what the real value of a sample from a landing-friendly area of Earth would be as far as drawing conclusions about global, or even regional processes.

Maybe I'm underestimating our present understanding of context here, and perhaps not appreciating objectives. Certainly this argument could be applied to anything short of a full geological survey of Mars. That being said, MSR does need to define very specific sampling objectives, IMHO. Do we want phyllosilicates, sediments, evaporites, or what, and what specifically are we trying to find out?

Sorry for the devil's advocate position here, but when we're talking about spending this kind of money critical questions will be asked; better be some really good answers.

Posted by: dvandorn Jul 15 2008, 04:07 AM

Exactly. If our $10 billion would buy us 100kg of samples, gathered by and trundled back to the MAV(s) by capable MSL-type rovers, picked up from a variety of landforms and geologic expressions, then I'd be all for it.

But if our $10 billion buys us a kilogram or less of soil and a few rock chips from within a grab-sampler-arm's reach of the MAV, then I don't care if God Himself is going to analyze the samples, the chances of finding anything truly instructive about Mars would, I think, be far less than if we spent the same money on three or four more MSL-capable rovers.

I strongly believe in bringing samples back from Mars. But I don't think a kg (or less) for $10 billion is worth the money. Not even worth $6 billion. IMHO.

-the other Doug

Posted by: Mariner9 Jul 15 2008, 05:03 AM

Most of the documents I have seen indicate that the baseline mission calls for collecting samples via rover for at least 6 months. Unclear to me if there is a large stationary lander with MAV mounted on it, with a rover returning with samples in tow, or if the lander is one large rover with MAV mounted on it.

In any event, it means that while you won't have samples from all over Mars, you at least get samples taken from a number of locations possibly ranging up to 10-20 kilometers away from the landing site.

Compare this to the MSR studies done in the 1980s. At that time there was a belief that Viking orbiters told them all they needed to know to get a site selected. And some studies even ommited any idea of a rover, and just had the lander grab rocks with a long robotic arm.

So really, 3 or 4 MSRs would be nice, but even just the one mission in 2020 would still be a tremendous advance in knowledge, and unlike the 1980s, we wouldn't be taking a shot in the dark on a location.

Maybe it really is time to bite the bullet and go for it. I keep thinking about Alan Stern's comment to the effect of "it's better to get 80 percent of something, than 100 percent of nothing".

In other words, no matter how long we wait, we're not likely to get the perfect set of MSR missions all over the planet, so why not at least get one?

Posted by: Juramike Jul 15 2008, 04:10 PM



One good argument for a Mars Sample return, even for just a small sample, is that a full and complete characterization of a Martian rock sample at one specific location using the full set of Earth-based instruments and equipment would give a solid benchmark to compare with all other locations on Mars.

This location would become the "home base" that we could use to reference all the other sites on Mars. It doesn't necessarily need to be representative, although it would be nice.









Posted by: SpaceListener Jul 15 2008, 04:12 PM

Well, I thought that the one of the good justifications to send the MSR mission is to have a very good evidence that the rovers or stationary spacecraft have found something very interesting that they are unable to identify or they have found some signals of past-present life. After that, everybody will nod "yes" to spend money for this mission.

No obstant, when I have learned that the http://www.marsdaily.com/reports/Russia_To_Study_Martian_Moons_Once_Again_999.html spacecraft would cost an astonishing small amount of money: USD 65 millions. I know that this mission would require much less mass and energy to accomplish but its difference is about 10-15 times that leads me to think about what NASA can improve the space program costs.

Posted by: dvandorn Jul 15 2008, 04:23 PM

I can't believe that $65 million is the entire cost of Phobos-Grunt. That may be what Russia plans on spending on just the spacecraft development and construction. I can't imagine it also includes launch costs or operational costs of mission ops, and I bet it assumes that a good deal of the overall cost will be borne by international partners.

AFAIK, even for Russian launch vehicles, $65 million won't even cover the launch costs.

And, like anything, I will believe these projected budget numbers out of Russia when the craft actually flies. Russia has been known in the past to make rather wildly inaccurate statements in terms of projected costs, just to try and convince others to help fund their programs.

-the other Doug

Posted by: SpaceListener Jul 15 2008, 04:30 PM

QUOTE (dvandorn @ Jul 15 2008, 11:23 AM) *
I can't believe that $65 million is the entire cost of Phobos-Grunt.

Doug

Thanks of your good comments since it has helped me to have a better understand about the Russia space program costs. Indeed, I feel that your terms are coherent.

Again thanks.

Posted by: JRehling Jul 15 2008, 04:59 PM

[...]

Posted by: Mariner9 Jul 15 2008, 05:59 PM

I agree that the 5 billion plus price tag makes this a very tough sell. I get the same sinking feeling when I read that NASA is considering delaying the Outer Planets Flagship by up to 4 years, and possibly raising the price to 3 billion in the process.

You compare that to MSL's budget busting 1.9 Billion, and it gets even scarier.

I'll believe in MSR when I see us 5 years and a billion dollars into this project, and not before.

- but ....

On the flip side, far from this mission not having any political appeal, I think it actually has a lot of appeal.

The general public doesn't really 'get' the science side of planetary exploration, but they get interested when we really go somewhere they can relate to. And generally that means landers.

Ten years ago Mars Pathfinder swas a media sensation, yet if I were to compare the relative contributions of Pathfinder vs. Mars Global Surveyor, I'd say MGS learned a lot more. Yet who remembers MGS?

Everyone knows about the MER rovers, but how many people even know that MRO, Mars Express, or Mars Odyssey exist? And how much would we really know about Mars if we only had done MER? Especially if we had used Viking data to select a landing site?

The public hardly noticed NEAR for the year it orbited Eros. But when it was gently set down, and spent a couple weeks gathering data (from only one instrument), it made headlines all over the world for being the first spacecraft to land on an asteroid. Probably less than 1% of the value of the NEAR mission came from that week on the surface, but it got 90% of the attention.


But even though MER excited the public, after we fly MSL, and then likely fly another rover in 2016 or 2018, just how excited are people going to be about rovers? They will be old news by then.

I think the public would be far more likely to get excited about actual samples returning from Mars.

Posted by: nprev Jul 16 2008, 12:05 AM

Might be a double-edged sword, though. The "Andromeda Strain" theorists will make a LOT of noise over it; the mission would not be without controversy.

Phoenix has actually retired this concern for me, since the soil pH determination seems consistent with abiological interpretations of the Viking results. I was a bit afraid that there was a very sparse population below the detection limits of really tough, active bugs that went wild over the Viking nutrients...not the kind of thing you want to get flushed down a lab drain or crash-land in the ocean.

Posted by: vjkane Jul 16 2008, 03:38 AM

If MSR happens and the $5-8B is spent, then that is an acceptable outcome. If it is decided soon that that budget is too much, and a smaller amount is spent on other rover/orbiter/network missions, than than is an acceptable outcome.

The real risk, in my mind, is that a number of leading space agencies "commit" to MSR, but then the whole thing collapses due to cost growth, a recession, or whatever. Then we may have forgone a decade of Mars exploration with no return. We lost a decade on Europa/Jupiter exploration while NASA committed itself to two technically unworkable solutions (the <$1B Goldin dream and then the >$$$$B Icy Moons Nuclear Propulsion fantasy). MSR is probably technically possible. I have severe doubts about multiple agencies securing the needed funding for almost 15 years to pull it off.

Posted by: AndyG Jul 17 2008, 09:51 AM

Mariner9 makes a number of interesting points, but I would have to wade in and say:

Pathfinder was a media sensation because it marked the birth of what we see today: images and data online (in all-but realtime) from a mission. The contrast to the pre-Internet era of space exploration and subsequent outreach was - as we've read many times on UMSF - gigantic. Therefore I would argue that Pathfinder's timing was as important to this sensation as much as its inherent success and spectacle.

The MERs longevity has counted against them in the media sensation stakes. They occasionally bubble up into the public consciousness, at least judging from my reading of the UK press, but it's hard to maintain any sort of momentum when the story appears to be: "Sol 1600 - more pictures from Mars" or "Spirit not quite dead yet". The missions are technologically impressive (very much so) but it's not "new News".

It's obvious that MSL will gather more detractors from the "it's got nukes" and the "but we've done rovers" camps nearer the time of its launch. IF MSR is lurking in the wings at that time, and with a guaranteed multi-billion price tag, then I can't see it surviving the usual short-termist criticisms that will no doubt be fired off by disgruntled politicians keen to raise their media profile.

4/ If you want to garner public support for future Mars exploration post MSL, then I'd agree with you - there needs to be a bit of the wow factor and showmanship - science led, naturally, but not averse to the sort of "money shot" we recently saw from MRO of Phoenix. And it needs to be affordable. My personal preference would be that it's maybe time to look at ballooning again: better range than a rover. Opportunities to touch down in multiple regions. Views of the envelope from orbit. What's not to love?

Andy

Posted by: djellison Jul 17 2008, 10:37 AM

NH got off the bad with barely a squeek from the anti-RTG crowd. I'd expect the same from MSL really.

Doug

Posted by: JRehling Jul 17 2008, 02:55 PM

[...]

Posted by: Greg Hullender Jul 18 2008, 04:30 AM

QUOTE (JRehling @ Jul 17 2008, 07:55 AM) *
I think Cassini broke the back of anti-RTG protest. Or people have had bigger things to protest since 1998.


I agree, but it's worth pointing out that it was the Earth Gravitational Assist and not the launch that got them worked up. The real test will be the next mission with an RTG that uses a VEEGA. However, given the people involved, I too predict no more protests on this topic.

We'll see.

--Greg

Posted by: mchan Jul 18 2008, 10:46 AM

The EGA was extra spice that allowed the hard core anti-nuke crowd to outdo themselves in painting doomsday scenarios and attracting more followers. Those folks get worked up even over the RHUs in MER.

But regarding the EGA, the canceled "Fire and Ice" Europa orbiter used a direct trajectory while the EGE and most of the Jupiter mission reference trajectories in the recent OPAG reports use an EGA. I had always wondered if that was just due purely to favorable planetary alignments, or was there some high-level policy involved.

The NH EIS included opposing responses from many of the same names involved in the Cassini protests. MSL will likely get about the same as NH, which, to be sure, is less than the circus raised for Cassini.

Posted by: Greg Hullender Jul 18 2008, 03:40 PM

QUOTE (mchan @ Jul 18 2008, 02:46 AM) *
The NH EIS included opposing responses from many of the same names involved in the Cassini protests. MSL will likely get about the same as NH, which, to be sure, is less than the circus raised for Cassini.


Those folks didn't have a lot to do back in 1999, but, as JR suggests, they've got far more interesting things to keep them occupied now and for the forseeable future. They'll write the occasional letter, but I don't think we'll see them devoting any of their resources to picketing or suing NASA again.

--Greg

Posted by: Mariner9 Jul 18 2008, 04:05 PM

QUOTE (mchan @ Jul 18 2008, 02:46 AM) *
But regarding the EGA, the canceled "Fire and Ice" Europa orbiter used a direct trajectory while the EGE and most of the Jupiter mission reference trajectories in the recent OPAG reports use an EGA. I had always wondered if that was just due purely to favorable planetary alignments, or was there some high-level policy involved.


I remember at the time that it was specifically stated that they would not use an EGA, and that was a high level policy mandated from some higher power. I was never clear on what motivated the policy. I always thought it was to make the mission have a shorter cruise time, but it might have been motivated by the Cassini protests (which were very recent at that time).

I remember when the Europa Geophysical Explorer studies started after the cancellation of Europa Orbiter, they made a point of saying the restriction had been removed.

Let me just interject my own emotional responce to using the EGA option. I don't mind using it to gain a good payload mass increase when it only lengthens the cruise from 3-4 years up to 6-7. But I really cringe when I see the studies come back with 10 year cruise times. They keep coming up with 4 year launch delays (most recently from 2016-2020), and increased cruise times (original goal was 6-7 years, but the Saturn orbiter proposal came in at 10 years) .....

I'm not getting any younger, but I still hold out (increasingly slim) hopes that I will live to see 2 more flagships.

Posted by: nprev Jul 18 2008, 04:22 PM

Hopefully not too OT, here, and definitely non-partisan from a political standpoint, but TPS has a very short survey in progress right now about the issues that they should advocate during the next US Presidential administration (whoever that might be): http://planetary.org/special/vision

I used the 'ask a question to the candidate(s)' section to push for more advanced propulsion research precisely so that transit times for missions can be reduced. I too want to see at least one more Flagship to the outer system before I croak, and of course something very effective in terms of cost and efficiency that might be available in time for MSR would go a long way towards making it happen.

Posted by: Vultur Sep 10 2008, 07:26 AM

As for the "Andromeda Strain" thing, is this just a matter of public paranoia? I really don't see how Martian bacteria adapted to a cold, alkaline, low-pressure environment could possibly survive in a human body. We can't even catch fish diseases ... is something from another planet even possible?

Posted by: Juramike Sep 10 2008, 02:40 PM

QUOTE (Vultur @ Sep 10 2008, 02:26 AM) *
As for the "Andromeda Strain" thing, is this just a matter of public paranoia? I really don't see how Martian bacteria adapted to a cold, alkaline, low-pressure environment could possibly survive in a human body. We can't even catch fish diseases ... is something from another planet even possible?


Probably not as a direct "pathogen/host" relationship.

But there are many examples of introduced things that have untoward consequences:

My garden just got devoured this summer by Japanese beetles, pretty little things that were introduced from a rose bush imported to New Jersey back in the 1800s. Another example is the Gypsy moths that were imported to try to grow silk (it didn't work) - they escaped and are destroying Eastern American forests. Cheet grass in the American West, eucalyptus trees in coastal California, fire ants in the American Southeast, escaped armadillos working their way from southern Florida, tiger mussels in lakes, purple loosestrife, Japanese stilt grass, etc., etc (the list goes on and on..)

I'd hate to be the guy responsible for introducing the bacterial rot that makes freeze-dried food obsolete.

***

At the same time, one of the purposes of Mars sample return will be to look for life, the possibility of life, or the signature of life. It will be imperitive that one can say that life detected from a sample from mars is uniquely martian with no possibility of laboratory contamination.

Either argument means the highest level of sterilization/containment/isolation of any martian samples will be necessary.

-Mike

Posted by: centsworth_II Sep 10 2008, 02:45 PM

QUOTE (Vultur @ Sep 10 2008, 03:26 AM) *
We can't even catch fish diseases ... is something from another planet even possible?

Your argument has lost out once before. laugh.gif

http://www.wired.com/science/discoveries/news/2007/07/dayintech_0720

We are so concerned about "infecting" Mars with Earth life. It seems logical that we be equally concerned with infecting Earth with (potential) Mars life. Humans need not be directly infected for an organism to reek havoc with the environment.

Posted by: Vultur Sep 12 2008, 08:40 PM

[quote name='Juramike' date='Sep 10 2008, 03:40 PM' post='125657']
Probably not as a direct "pathogen/host" relationship.

But there are many examples of introduced things that have untoward consequences:

<snip>

***

At the same time, one of the purposes of Mars sample return will be to look for life, the possibility of life, or the signature of life. It will be imperitive that one can say that life detected from a sample from mars is uniquely martian with no possibility of laboratory contamination.

Either argument means the highest level of sterilization/containment/isolation of any martian samples will be necessary.

-Mike
/quote]


Oh, I didn't think of the possibility of confusion - It makes sense, especially since Mars life might well be derived from Earth through an ALH-like meteorite.

Posted by: JRehling Sep 12 2008, 09:12 PM

[...]

Posted by: Vultur Sep 13 2008, 12:03 AM

QUOTE (JRehling @ Sep 12 2008, 09:12 PM) *
I think if you view the payoff matrix, it's the magnitude of the consequences that puts the issue into play, sort of like Pascal's Wager.

Suppose MSR has a 99.9% probability of enlightening us scientifically, and pretending that science has units, on a par of two times the value of Apollo, Viking, and Voyager combined...

...and a 1 in a quintillion probability of wiping out all life on Earth.

That payoff matrix for expected outcomes sums deeply to the minus.

So as securely as you might conclude that meteorites prove that there's no hazard, you don't want to the postscript to be the last nine survivors of humanity in a bunker reviewing the aftermath and saying, "Oh... THAT's why there was no hazard with meteorites, but there was with MSR. Didn't think of that."


OK, that makes sense - but I wasn't basing anything on meteorites; just on how different the conditions of Mars are from those on Earth (or inside a human body). The biggest threat would be relatively recent (a few million years) microbes brought to Mars as spores, and mutated by radiation.

(Also, I don't think there's any probability of wiping out all life -- aren't all diseases strictly limited by how much they can spread before the host dies?)

Posted by: dvandorn Sep 13 2008, 01:51 AM

As I recall, Mike Collins noted in re the Apollo quarantine procedures that you take a very, very small number -- the chance of an organism that could destroy life on Earth being returned from the Moon -- and you multiply it by the extremely large number of the damage that such an organism would cause. The result of that equation is a small but significant number, and on that basis a certain amount of precaution must be taken.

-the other Doug

Posted by: ElkGroveDan Sep 13 2008, 02:02 AM

It's an exercise in arbitrary risk assessment. How do you quantify the multiplier of potential damage? Why stop at a quintillion? If the potential damage is destruction of all life on Earth then you have a damage multiplier approaching infinity, and then the risk becomes very large too.

Let's not worry about imaginary risks we can't quantify and get on with the business of exploring. When we have the slightest reasonable shred of evidence of life somewhere then we can start crunching numbers. Until then it's an empty, meaningless pursuit.

Posted by: Vultur Sep 13 2008, 03:01 AM

QUOTE (dvandorn @ Sep 13 2008, 02:51 AM) *
As I recall, Mike Collins noted in re the Apollo quarantine procedures that you take a very, very small number -- the chance of an organism that could destroy life on Earth being returned from the Moon -- and you multiply it by the extremely large number of the damage that such an organism would cause. The result of that equation is a small but significant number, and on that basis a certain amount of precaution must be taken.

-the other Doug


That makes sense -- if you accept the assumption that there is even a possibility of a foreign organism destroying life on Earth. I simply don't see how, even if it wasn't hampered by terrestrial conditions being so different from Martian ones, something that evolved in an ultra-depauperate ecosystem almost without competition could compete successfully with Earth's robust ecology. You'd need a foreign ecology at least as competitive and advanced as our own -- placentals overran the marsupials of South America, and when introduced by humans, are seriously damaging the marsupials of Australia and the birds of NZ, because they evolved in a more competitive environment with more species (N America + Eurasia + Africa, while all the others were islands).

Posted by: Juramike Sep 13 2008, 05:19 AM

In a favorable growth environment, E. coli will double in number every 20 min. Unchecked, we'd be hip deep in E. coli in just a few days. A culture oven, agar growth media, and bam! it takes off.

If something from Mars was just scratching a living and barely surviving on the (sub)surface at real low temperatures, then got put on Earth with warmer temps, plentiful water, organic food sources abundant, and higher pressure atmosphere it might grow unchecked. (If the biochemistry was too alien, maybe nothing on Earth would consider it food!). The stuff could make life miserable just by overrunning everything. Space kudzu!

There are risks, we should be cautious, but we shouldn't stop exploring.

-Mike

Posted by: JRehling Sep 13 2008, 05:36 AM

[...]

Posted by: dvandorn Sep 13 2008, 05:52 AM

Yeah. To paraphrase any number of people, the Universe ain't safe. It's beautiful, it's fascinating, it's glorious -- but if you want safe, go hide under your bed. (And even then, you ain't safe.)

The possibility of finding an alien microbe that could do great damage is probably on the same order as the Earth passing directly through the focused emission from a nearby gamma-ray burster. Either holds the potential of ending all life on Earth. The real difference is that we can take steps to make the threat from alien microbes even more remote than it already is, while there is nothing we can do about a close GRB (or a close supernova, or the passage of a large dark body through the inner Solar System, etc., etc., etc.) except to hope for just enough warning to insert our heads deeply between our knees, so we can kiss our arses g'bye!

rolleyes.gif

-the other Doug

Posted by: Zvezdichko Sep 13 2008, 09:48 AM

Why don't you ask the biologists smile.gif It's simply impossible for an alien microbe to do any damage to our organisms wink.gif

What worries me more is yet another delay of the mission.

Posted by: Vultur Sep 13 2008, 05:00 PM

QUOTE (Juramike @ Sep 13 2008, 06:19 AM) *
In a favorable growth environment, E. coli will double in number every 20 min. Unchecked, we'd be hip deep in E. coli in just a few days. A culture oven, agar growth media, and bam! it takes off.

If something from Mars was just scratching a living and barely surviving on the (sub)surface at real low temperatures, then got put on Earth with warmer temps, plentiful water, organic food sources abundant, and higher pressure atmosphere it might grow unchecked. (If the biochemistry was too alien, maybe nothing on Earth would consider it food!). The stuff could make life miserable just by overrunning everything. Space kudzu!

There are risks, we should be cautious, but we shouldn't stop exploring.

-Mike


Yes ... the real risk would be that it considered an Earth environment more favorable than Mars. That would probably mean it was terrestrial originally and recently ... otherwise it would be too adapted to Mars conditions and Earth would kill it. Thinking about this more, have there been any recent impacts big enough to throw meteorites to Mars? What's the risk of Viking, say, carrying microbes that could mutate in the high radiation environment? This seems the most likely threat (though still very unlikely, of course).

Posted by: Shaka Sep 13 2008, 07:52 PM

QUOTE (Zvezdichko @ Sep 12 2008, 11:48 PM) *
Why don't you ask the biologists smile.gif It's simply impossible...

We biologists never say, It's simply impossible... cool.gif

Posted by: Zvezdichko Sep 14 2008, 09:01 AM

OK, sorry. I'm a biologist and will correct myself. The chance is extremely low.

Posted by: PhilHorzempa Dec 5 2008, 04:44 AM

I am surprised that Mars news from earlier this week seems to have escaped the notice of most. I am referring to NASA's solicitation on December 1, 2008 for Mars Ascent Vehicle Technologies, including concepts for MAV propulsion.
This is absolutely great! It seems that MSR has officially begun with this solicitation. What I like about this is NASA's desire to begin to reduce the technology risks for MSR as early as possible. I imagine that they have learned some lessons from MSL's mess stemming from an insuffficient Phase B and insufficient Mars Program technology development.

Here is the link to the solicitation -

http://www.spaceref.com/news/viewsr.html?pid=29993


Another Phil




Posted by: ngunn Dec 5 2008, 11:54 AM

This seems to me hugely significant and very welcome. (Admins please delete if it's already appeared in another thread or move to a new thread if wou think it warrants one.) Mars sample return will now presumably be a joint venture.

http://www.planetary.org/blog/article/00001763/

Posted by: mcaplinger Dec 5 2008, 02:33 PM

QUOTE (PhilHorzempa @ Dec 4 2008, 08:44 PM) *
It seems that MSR has officially begun with this solicitation.

Not to rain on anyone's parade, but this is about the fifth such solicitation in the past 15 years. They result in some viewgraphs but nothing much else.

Posted by: mcaplinger Dec 5 2008, 05:08 PM

QUOTE (ngunn @ Dec 5 2008, 03:54 AM) *
Mars sample return will now presumably be a joint venture.

Again, not to be a wet blanket, but Weiler and the leaders of CNES made a similar agreement in 2002. Talk is cheap, funding reality something else.

Posted by: Mariner9 Dec 5 2008, 08:05 PM

Going furthur back, there were all the MSR studies at JPL in the 80s. The cost estimates were rather large, and MSR dissapeared for a decade or so while NASA moved on with Pathfinder and MGS.

And remember the late 90s? At that time Mars Sample Return was supposed to happen with the 2005 Mars launch opportunity. Somewhere along the line the French were going to provide the orbiter that would pick up the sample and return it to Earth.


Then Mars98 went down in flames, and NASA initiated a slate of more feasable (and properly funded) missions with MER and MRO.

The French orbiter turned into Netlander, then dissapeared altogether.


The bottom line is, MSR is tough to do, expensive as hell, and the launch date has been slipping for decades.

I'll believe MSR is happening about the time they bolt the first spacecraft to a launch vehicle.

Posted by: PhilHorzempa Dec 20 2008, 09:05 PM

I agree with those who point out that Mars Sample Return is tough to do and can be expensive. Let me suggest one way in which NASA can make MSR less difficult and less expensive.
I poropose that NASA omit any rover on its MSR Lander payload. If you scan through recent documents discussing the details of an MSR mission, then you will see that they include some type of rover. This rover would be designed to fetch a sample cache from an earlier rover and/or obtain samples of its own. In fact, one area of concern expressed in a recent document is that the MSR rover, if it does not pick up a sample cace, but must collect all of the samples for the MSR, will have only a few months to accomplish its mission.
I propose that NASA make the next planned rover, the Mars Prospector, an integral part of MSR. This will take care of several issues at once. The elimination of any type of rover on the MSR Lander will immediately result in savings of mass and a reduction in complexity. Both of those aspects will save a lot of money, both by allowing a less expensive booster to be used and by simplifying design, construction and testing of the Lander element of MSR. Without the need to stuff a rover on the landing platform, NASA will be able to focus on designing a reliable Mars Ascent Vehicle. In addition to the MAV, the Lander element could have a deep drill for sampling, as well as a simple scoop for contingency sample acquisition. Those aspects of the Lander element have already been prposed in recent MSR documents.
If the MSL rover proves that it is as long-lived as the MER rovers, then this will only add further support to my proposal to use the Prospector Rover as the primary means of sample acquisition for MSR. It will have had at least 1 year to prove itself before the MSR Lander is launched. By the way, adding a rover to the MSR Lander will not guarantee success, as that rover could go belly-up from day one of the mission.
By using the Prospector rover for MSR, we can make MSR more plausible. This does add a bit of risk to MSR, but I feel that not utilizing one of NASA's long-lived rover assets would be a waste. MSR must be made to be affordable or it will continue to be deferred.
My guess is that the Mars Prospector Rover could be launched in 2018 or 2020, with the NASA Lander/MAV and ESA Orbiter elements launched in 2020 or 2022.
I am guessing that there are a number of JPL and NASA folks who read UMSF. Can you tell me why this idea is not the way to go in this age of limited budgets?

Another Phil






Posted by: sci44 Dec 21 2008, 12:14 AM

With regards to recent NASA/ESA discussions, it looks like the 2016 "Mars prospector" mission is already starting to merge with ExoMars - there may not be a separate NASA mars rover mission - especially with the MSL overrun. However, assuming there is a Mars Prospector type mission prior to MSR, there are going to be a lot of "if's" - is it going to survive the x year gap between missions? How accurately are you going to land MSR? Sure we have been lucky with the MERs - but is MSL even going to be going as long as these?
Another point worth mentioning - unless someone starts making some Pu238 soon, any future Mars mission is not going to look like, or be based directly on MSL, since, as we all know, there is a dire shortage of Pu238 - and no one wants to stamp up the dollars ($250m Clinton era- probably closer to $0.5-1bil now?) to build a reactor to make more. RTGs only look cheap when using up Cold-war era stocks.

I think the problem is even wider than that. For instance, given the difficulty Phoenix had in getting volatiles delivered, just a few feet and in a day, to the science instruments, how much more difficulty is there in doing this and safely returning such samples, uncontaminated and complete, over a year later, to Earth? If MSR is just one large major mission like MSL, how much is it really going to be telling us about Mars as a whole? Remember with the moon missions, we had multiple impactors (Rangers), soft landers (Surveyors) and then 6 Apollo missions - and we still didn't find out about the potential volatiles at the poles until the 90's. Given that one objective is to prove Mars is sufficiently sterile that a manned mission would not ruin it, I would have thought more than one sample point is desirable.

I am sure someone more qualified will correct me, but I had the impression that the real show-stopper for MSR is the landed weight for a return rocket (even the more modest orbital docking version) - rather than the rover/mobility aspect. One interesting proposition by a space enthusiast (will dig up a ref later) suggested a much more modest MSR mission - using a very small solid booster rocket *just* sufficient to deliver a small Mars sample package to low orbit, together with a beacon - the package would have no manuevering capacity. The sample is picked up in orbit by the return craft. That way, all the weight and complexity of Earth-return is shifted to the orbital craft - the landed portion could be modest in size. The advantage to this approach could be having more than one sample return lander - one or two orbital pickup/return craft could collect samples from many smallish landers..

Edit: Can't find the article I was looking for, but this is http://homepage.ntlworld.com/bobparkinson/Mars/MSR.doc.

Posted by: imipak Dec 21 2008, 12:36 PM

QUOTE (PhilHorzempa @ Dec 20 2008, 09:05 PM) *
I propose that NASA make the next planned rover, the Mars Prospector, an integral part of MSR. [...]


Google turned this up, http://www.lpi.usra.edu/pss/presentations/200806/02meyer.pdf (Michael Meyer, 2008):

QUOTE
Mars MER+ Rover (aka Mars Prospector Rover)
– MER+ rover deployed by “Sky Crane” to new water-related geologic targets
– Precision landing (<6-km diameter error ellipse) enables access to new sites
– Conducts independent science but with scientific and technical feed-forward to MSR
As a precursor, this opens the possibility for payload trade-offs with MSR Lander


(Emphasis mine.) So it seems thoughts along those lines are being considered. AFAIK MSL is unlikely to be still around in the 2020 timeframe - RTGs can't be cleaned by lucky gusts of wind.

Posted by: SteveM Dec 22 2008, 03:16 PM

QUOTE (imipak @ Dec 21 2008, 07:36 AM) *
AFAIK MSL is unlikely to be still around in the 2020 timeframe - RTGs can't be cleaned by lucky gusts of wind.

AFAIK, dust will have little effect on the operation of an RTG (it may hinder the cooling of the RTG but that shouldn't cause major problems) and Pu238 has an 87.7 year half-life.

Steve M

Posted by: Stu Feb 21 2009, 07:47 PM

I clicked on this link because I was naturally excited to hear a local firm is involved in a Mars mission. Iassumed, before reading, it was related to MSL... turns out it's an ESA sample return mission...?

http://www.cumberland-news.co.uk/workington_firm_to_play_key_role_in_mars_mission_1_516996?referrerPath=business/


Posted by: ustrax Feb 21 2009, 07:57 PM

It looks like they're talking about ExoMars there Stu...

Posted by: Stu Feb 21 2009, 08:43 PM

I guessed that. I was just surprised by the details about the "sample return" plans.

Posted by: Hungry4info Feb 21 2009, 10:05 PM

QUOTE (SteveM @ Dec 22 2008, 09:16 AM) *
AFAIK, dust will have little effect on the operation of an RTG (it may hinder the cooling of the RTG but that shouldn't cause major problems) and Pu238 has an 87.7 year half-life.

Steve M


While we're on the subject, assuming MSL lands safely, and some point through the mission doesn't get obliterated by an asteroid or fall down a cliff or whatever else could unexpectedly end the mission, what is the limiting factor on the lifespan of MSL? What about useful lifespan? I sometimes imagine after a 5 or 10 year mission, a crippled rover staying stuck in one spot, but alive, for 20 more years.

What will limit the lifespan of MSL? RTG energy output?

Posted by: helvick Feb 22 2009, 02:33 AM

QUOTE (Hungry4info @ Feb 21 2009, 11:05 PM) *
What will limit the lifespan of MSL? RTG energy output?

At this stage I'd be willing to bet that the most likely limiting factor will be budgetary constraints or simple disinterest on the ground because there will be more profitable things to spend the money on in terms of supporting active assets on Mars at that point in time.

No matter what amount of power the RTG is actually able to produce I think that it would be highly improbable for MSL to ever "go dark" because it ran out of juice. Mechanical or electrical failure might kill it, dust build up on sensors\cameras\antennae might render it useless and it might even be driven off a cliff (!) but once it lands the most likely end of mission scenario for it is going to be some human on the ground deciding to turn it off, or at least turn off the things on the ground that listen to it.

The Pu-238 in the RTG has a half life of 87.7 years. However the RTG hardware itself degrades over time aswell so looking at the Voyager RTG's as an example of a mission tested over a sufficiently long period of time the evidence is that an operational RTG of this general type has an effective half life of around 71.5 years.

The MER's initially had an expected power output of 700-900 watt hours / Sol and we initially believed that they would rapidly fail\die once power levels dropped below about 280 watt hours / sol. As it happens while the 280 watt hours per sol number was the minimum value needed to operate the rovers as they were initially intended to be operated, the clever engineers\drivers\designers\PI's and the rest have proven that they can be kept alive (with human intervention) more or less indefinitely provided power levels can be kept above 180 watt hours / sol. It seems reasonable to me to conservatively estimate that they improved on the efficiency of the design by about 35% just by being smart about how they operated the rovers when you just look at it in terms of survivability relative to available power.

Since MSL is known to have a dependable power source the design will certainly not include the sort of 3x power margins that the MER's had to have built in (in case of dust storms in the first 90 days, worse dust deposition than was actually seen etc) but I'd still expect that during the mission the MSL team will learn to operate her more efficiently and it would surprise me if they failed to find at least 50% of the sort of savings that the MER's have found. So let's say they can only realistically expect to "find" 17% savings in terms of survivability vs available power over the lifetime of the mission.

Also lets assume that they build in zero power margin for the end of primary mission - ie MSL is intended to end its first Martian year generating precisely as much power as the design says is the minimum survivable level (equivalent to what we all thought was 280 Watt hours for the MER's way back when).

Assuming the RTG's have not improved at all since the Voyager days and that operational brilliance can only eek out another 17% margin over the designed minimum power demands of MSL then it might live for an additional 19 years or so before its power levels fell below 17% of the minimum designed for the primary mission (assuming the above mentioned 71.5 year effective half life for the RTG).

And I think I'm being conservative there. So back to my original point, EOM for MSL will be somebody down here turning it off not MSL running out of juice. Assuming she lands safely and all that, that is.

Posted by: mcaplinger Feb 22 2009, 05:58 AM

QUOTE (helvick @ Feb 21 2009, 06:33 PM) *
No matter what amount of power the RTG is actually able to produce I think that it would be highly improbable for MSL to ever "go dark" because it ran out of juice.

I think battery life is still a significant limiter on the mission lifetime. That's what ultimately killed VL2 and would have killed VL1 had it not been miscommanded first.

Also, there are many factors in RTG degradation, not just the Pu decay. See "DEGRA : a computer model for predicting long term thermoelectric generator performance" at
http://trs-new.jpl.nasa.gov/dspace/handle/2014/38760

Posted by: dvandorn Feb 22 2009, 06:48 PM

Exactly -- recall that NASA tried to turn the ALSEPs back on in the early 1990's and none responded. The best theory as to why none responded was that the voltage being generated by the RTGs, less than 25 years after emplacement, had fallen below minimum levels for operating the transmitters.

-the other Doug

Posted by: helvick Feb 22 2009, 09:27 PM

Battery lifetime wasn't something that I'd considered. The LiIon batteries for MSL and the power management\battery control subsystem will be pretty similar to those used on the MERs so the best data we have on that is the MER experience, I'm pretty sure they are actually running longer than the longest tests of those batteries so the best we can say is that MSL's batteries should at least be able to match the MER's. The detailed engineering performance data on the MER batteries should give a much better idea of precisely how long they can be expected to last but the only reports that I can find online for free say that the MER batteries had degraded by ~10% in terms of charge capacity after 30 months of operation. With an RTG power source the management of the battery lifetime on MSL should be easier than on the MER's but it's pretty much guaranteed that the mission planners will be driving the batteries hard during the primary mission, at least I certainly hope they will. So 5 years with the batteries still capable of supporting mobility is pretty much guaranteed.

Thanks for the Degra link Mike - I'd just (stupidly) pulled some data from a source that said the Voyager RTG's were delivering 80% of their initial power after 23 years. I should have thought that was a bit off. The report you link puts the actual power drop off at ~30% after 30 years which is more or less equivalent to an effective 40 year half life. Using that as a better model MSL's RTG should degrade to 17% below the planned EOM power levels after 11 years.

In any case she will have more than enough power to keep running in some fashion for a very long time after the end of the 1 year primary mission.


Posted by: Stephen Feb 23 2009, 02:48 AM

QUOTE (Stu @ Feb 22 2009, 06:47 AM) *
I clicked on this link because I was naturally excited to hear a local firm is involved in a Mars mission. Iassumed, before reading, it was related to MSL... turns out it's an ESA sample return mission...?

http://www.cumberland-news.co.uk/workington_firm_to_play_key_role_in_mars_mission_1_516996?referrerPath=business/
"Workington engineering firm Gravatom will help design a lab to hold rock samples from the red planet, following a planned trip in 2016."
Would I be interpreting that correctly as somebody contemplating an MSR mission for 2016? Or has somebody simply made a typo (for 2018; or 2026)?

======
Stephen

Posted by: Mariner9 Feb 24 2009, 04:25 AM



Quoting the article:

A rocket will be launched that will send a rover to the surface of Mars to drill into the surface and test for any evidence of organic material.

A subsequent ‘Mars sample return mission’, involving all of the major world space agencies, will then be launched.



How I read that is the 2016 mission would be only a rover, and that that rover would have a sample cache on it.
The subsequent mission would be the MSR, launched at a later date.

Now, given that MSR has been studied in different forms for well over 20 years (including joint missions with ESA and or the French), I don't think this is anything close to a sure bet.

Posted by: vjkane Feb 24 2009, 05:35 AM

QUOTE (Mariner9 @ Feb 24 2009, 05:25 AM) *
Now, given that MSR has been studied in different forms for well over 20 years (including joint missions with ESA and or the French), I don't think this is anything close to a sure bet.

see http://futureplanets.blogspot.com/2009/02/great-website-saturn-ring-observer-and.html

Posted by: Fran Ontanaya Feb 24 2009, 04:18 PM

Wouldn't it be more interesting to thoroughly analyze and understand the martian dust background and ice background to remove that noise and provide a 'blank' profile for the hundreds of in situ analysis? I.e. if the clays, carbonates or perchlorates that Phoenix detected ever go airborne, knowing about them beforehand would have been useful to design the TEGA and MECA instruments.

What could be the cost of landing on top of Olympus Mons, sit idle collecting atmospheric dust and ice, and send it to LMO --including lower biohazard costs, a smaller sample, and simpler sampling hardware--, as opposed to a fully fledged MSR mission?

Posted by: stevesliva Feb 24 2009, 07:44 PM

QUOTE (Fran Ontanaya @ Feb 24 2009, 12:18 PM) *
What could be the cost of landing on top of Olympus Mons, sit idle collecting atmospheric dust and ice, and send it to LMO --including lower biohazard costs, a smaller sample, and simpler sampling hardware--, as opposed to a fully fledged MSR mission?


Landing with that little atmosphere is tough. Volcanic rock is also probably way down the list of rock types they want.

Posted by: Stu May 3 2009, 07:05 AM

This week's Carnival of Space (the 101st) is being hosted at the "Robot Explorers" blog of writer David S.F. Portree. http://robotexplorers.blogspot.com What's that got to do with MSR? Well, David's site has lots - and I mean LOTS - of very detailed info about MSR missions that have been proposed and dsigned over the years. If MSR is an interest of yours, go take a look.

Posted by: Vultur May 4 2009, 10:01 AM

I still don't understand the necessity of biohazard precautions, except as a PR move. I understand the idea that even a tiny chance of a big disaster is worth avoiding - but the idea that Mars microorganisms could cause disease in Earth life is biologically laughable. (And 'gray goo' scenarios are just fear-mongering nonsense, whether biological or nanotechnological).

No Mars organism could survive Earth - even if the pressure, temperature, and radically different chemical environment wasn't fatal, the island biogeography effect would cause it to die off almost immediately. Lots of invasive species are a problem on Hawaii, but we don't see Hawaiian pests invading the continents. This is the same thing, but (literally) more than a million times moreso; Mars can't possibly have a biosphere complex enough for anything on it to be competitive with Earth life.

In a way, it can be compared to the LHC paranoia - except that we understand the reasons why a Martian organism CAN'T cause disaster far better than we understand the implications of high-energy particle physics.

EDIT: The main reason why I care is that I think we need to leave the option of direct-to-Earth MSR open.

EDIT again: At risk of a tl;dr:

In a hypothetical case where the funding was provided now (say *insert multibillionaire here* said "here's a blank check, do MSR") how soon could it be done, and what would the biggest challenges be?

Posted by: cbcnasa May 4 2009, 12:14 PM

It is better to use the caution for the media which will say we don't know what can be brought back better to follow the slow procedure.

Posted by: Paolo Sep 8 2009, 05:42 PM

This has passed relatively unnoticed, but it could be a step forward for an affordable Mars Sample Return Mission
http://www.nasa.gov/home/hqnews/2009/aug/HQ_09-194_ALICE.html
I have never been a fan of in situ resource utilization, I think its benefit must be weighted against the added complexity, but this seems relatively straightforward

Posted by: mcaplinger Sep 8 2009, 07:39 PM

QUOTE (Paolo @ Sep 8 2009, 10:42 AM) *
...but this seems relatively straightforward

Manufacturing nanoscale aluminum in situ seems fairly difficult. For that matter, even extracting aluminum in situ would be challenging.

I don't think that taking the aluminum to Mars and using in situ water would be a viable approach, but I could be wrong.

Posted by: Paolo Sep 8 2009, 08:00 PM

QUOTE (mcaplinger @ Sep 8 2009, 09:39 PM) *
I don't think that taking the aluminum to Mars and using in situ water would be a viable approach


This is what I meant

Posted by: mcaplinger Sep 8 2009, 08:46 PM

QUOTE (Paolo @ Sep 8 2009, 12:00 PM) *
This is what I meant

What's the relative mass fraction of aluminum and water in this? I can't get to more than the first page of the AIAA paper.

Posted by: Paolo Sep 9 2009, 05:17 AM

Unfortunately there is not much technical information on ALICE on the net. The only thing I could find was the first page of the AIAA paper. Perhaps we could contact the authors and ask for a full copy

Posted by: Phil Stooke Oct 1 2009, 08:26 PM

I'm looking for a map that I am sure I've seen, but now can't find. Can anyone help?

This was a map of a projected Mars Rover Sample Return mission with rover traverse. Back in c. 1988-90 there were several studies of these missions, especially at a set of ten sites identified at USGS by Harold Masursky and colleagues. Most of those sites were mapped in detail and published in the USGS Misc. Investigations series, identified as 'Science Study Areas'. Some of those maps (Olympus Mons, Memnonia, Mangala Valles etc.) showed the rover routes, others didnt. Some of the missing routes were shown in the Mars Landing Site Catalog.

But I'm missing one... Chasma Boreale. I am certain I've seen a map of a possible rover traverse in Chasma Boreale. Now I can't find it. It's not in the Mars Landing Site Catalog as I had mis-remembered. There is a version in a 1988 MEVTV workshop but it's not what I'm thinking of. Does anyone have any idea where it might be?

Phil

Posted by: PDP8E Oct 1 2009, 08:57 PM

Chasma Boreale is the polar region traverse? ...here is Masursky's map for that region (bottom-ish)

 nph_iarticle_query.pdf ( 241.41K ) : 515




Posted by: Phil Stooke Oct 1 2009, 08:59 PM

Thanks... but unfortunately that's the MEVTV workshop one that I have already. There's another one out there somewhere that I'm missing. But I'm grateful for you for finding that one.

Phil

Posted by: ElkGroveDan Oct 1 2009, 11:51 PM

Phil whenever I've searched and searched for something I eventually turn to the amazing Google Book Search. A lot of old books are there full text, but a most are just a reference. Anyway, here are a couple of candidates that you might be able to track down in a library or the Library of Congress.

http://books.google.com/books?client=firefox-a&q=Chasma+Boreale+%22sample+return%22&btnG=Search+Books

Posted by: Phil Stooke Oct 2 2009, 12:25 AM

Also thanks for this! Sadly those don't include the map I'm looking for. I'm sure I've seen it, but I'm drawing a total blank now I'm trying to find it. I was so sure it was in the Mars Landing Site Catalog (the second of your links), but that has only text, not the map.

Truth is, if it could be found easily on Google I would have it already. I'm hoping somebody involved in this work might see this and remember it.

I really appreciate people trying to help with this!

Phil

Posted by: ElkGroveDan Oct 2 2009, 04:19 AM

QUOTE (Phil Stooke @ Oct 1 2009, 05:25 PM) *
Truth is, if it could be found easily on Google I would have it already.

Well I figured that, but the Book Search requires a separate effort that most people overlook.

Good Luck.

Posted by: monitorlizard Oct 3 2009, 05:32 AM

This is a real long shot, but might it be from "Viking Rover Studies", NASA Contractor Report 140391? This is from my (rather poor) memory, but I recall rover traverse maps for something like three different landing sites. It seems like one was a polar site, but it could have been the Martian south polar area. Anyway, the report is from July 1974, so it probably doesn't fit your criteria, Phil.

Posted by: Phil Stooke Oct 3 2009, 11:54 AM

Thanks... that was indeed the south. I'm beginning to wonder if I dreamed the whole thing. I would have sworn that it was in the Mars Landing Site Catalog, but it isn't. The site is, but not the rover traverse. Did I confuse it with one of the traverses that is in the Catalog? Maybe. I'll post a few of the traverse maps I've made next week to show what I'm doing.

Phil

Posted by: monitorlizard Oct 4 2009, 05:26 AM

I'll give it one more try,Phil. My best guess would be something from The First (or Second, or Third) International Conference on Mars Polar Science and Exploration. The First was held in 1998, the Second in 2000, and the Third in 2003.
The abstracts were published by LPI and may be available online, but are definitely available in print (First and Second) and CD-ROM (Third) form. Other than that, my only other guess would be an LPSC abstract. Good luck.

Posted by: PhilCo126 Oct 4 2009, 09:31 AM

Indeed, LPI has a few books on Mars Sample Return.

Posted by: gndonald Oct 14 2009, 04:22 PM

The Beyond Apollo weblog has been posting a series of articles on Mars Sample return missions, the latest article covers a 1976 proposal to collect a sample of ice from the Martian South pole using modified Vikings.

See: http://beyondapollo.blogspot.com/2009/10/mars-polar-ice-sample-return-1976-1977.html

Posted by: Phil Stooke Oct 14 2009, 04:37 PM

I should add that David Portree is trying to help me find that missing traverse map, but I've come to the conclusion I was confusing it with one of the others in the Mars Landing Site Catalog, possibly one at Durius Valles (site 079 in the Catalog). I was just so sure I had seen it, but that is, increasingly, a bad sign!

Phil

Posted by: Phil Stooke Oct 14 2009, 04:44 PM

Here is an example of a set of perhaps little known traverse suggestions dating from the Mars Surveyor 2001 planning phase. Mars Surveyor 2001 was originally going to land an Athena rover similar to MER, which might travel a few tens of km. At the first landing site workshop, these traverses were suggested as well as lots of other sites without specific traverses. Then the mission was descoped and the rover would be similar to Sojourner with a maximum range of about 1 km. Then it was cancelled, and eventually the spacecraft flew as Phoenix, without a rover.

Phil


Posted by: vikingmars Oct 14 2009, 10:26 PM

Full inline quote removed. Hey - it was Phil's idea. - ADMIN

smile.gif ...And I like the "Thyra" crater site, because it's a few km away from our Columbia Hills in Gusev crater ! smile.gif

Posted by: Phil Stooke Oct 15 2009, 02:04 PM

Every time I look at that place I want to call it 'Thyra', but I have to force myself to correct it - it is officially 'Thira'.

(PS - you'll get into trouble for that big quote!)

Phil

Posted by: pospa Jun 16 2011, 11:14 AM

These days, 16.-17.6. 2011 is http://mepag.jpl.nasa.gov/meeting/jun-11/index.html taking place in Lisboa, Portugal (I guess first time out of USA).
Another clear sign of NASA taking European guys more into the club.

At least 5 presentations about MSR are available today already - scientific objectives, sample size, number of samples, sampling priorities and strategies, etc., etc.

Posted by: stone Oct 18 2015, 04:22 PM

Here might be the best place to ask a question I always have when it comes to MSR.

The rocket which launches the capsule from Mars needs a certain size, but the images I have seen are always impression from artists, and from the ExoMars rover I know how wrong this "impression" can be.

What is the rocket size to launch a 100kg satellite to a stable orbit around Mars?

I assume that that will be a solid fuel rocket with one or two stages.

Is there a nice program to do the calculations?

Posted by: mcaplinger Oct 18 2015, 04:54 PM

QUOTE (stone @ Oct 18 2015, 09:22 AM) *
What is the rocket size to launch a 100kg satellite to a stable orbit around Mars?

The math is simple enough -- https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation -- but the devil is in the details.

The 100 kg is obviously arbitrary. http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4342.pdf (which was just the first google hit I found) assumed a payload mass to orbit of 36 kg, 5 kg of which was sample -- this was a two-stage hybrid rocket. Total vehicle mass at liftoff is 288 kg. A single stage was found to be feasible if the payload mass was reduced to 1 kg.

Posted by: mcaplinger Oct 18 2015, 05:32 PM

BTW, http://web.stanford.edu/~cantwell/Recent_publications/Boiron_AIAA_2013-3899.pdf is a good review of the history of MAV and ISRU development from the same group that's pushing this hybrid design. I'm afraid they are glossing over a lot of the system complexity issues with their design, but that's pretty typical for this area.

Posted by: djellison Oct 18 2015, 11:16 PM

QUOTE (stone @ Oct 18 2015, 08:22 AM) *
What is the rocket size to launch a 100kg satellite to a stable orbit around Mars?


FWIW - a sample return canister launched from Mars would almost certainly be an order of magnitude smaller than that.

Posted by: scalbers Apr 27 2016, 06:04 PM

Greetings - here's an announcement of opportunity about MMX for Martian Moons Sample Return.

http://www.spaceref.com/news/viewsr.html?pid=48736

Posted by: JRehling Sep 30 2017, 03:11 AM

I haven't seen last month's MSR news on UMSF yet and this is the place where it should go:

http://www.planetary.org/blogs/jason-davis/2017/20170828-mars-2020-sample-return.html

It seems like there's a disconnect between the short time between now and 2026 and the complexity of the architecture. I suppose it's possible to start a multi-mission sample return before the architecture is finalized (and perhaps, in the form of the 2020 rover, we already have), but that seems a bit risky with the stakes and costs so high.

If the Mars Ascent Vehicle has no rover and relies upon an already-active rover to survive long enough to deliver samples to it, that simplifies the architecture enormously, but risks the failure of the rover before the MAV arrives. I suppose a simplicity-and-risk tradeoff is inevitable with something as big as this.

Posted by: vjkane Sep 30 2017, 02:39 PM

QUOTE (JRehling @ Sep 29 2017, 07:11 PM) *
I haven't seen last month's MSR news on UMSF yet and this is the place where it should go:

http://www.planetary.org/blogs/jason-davis/2017/20170828-mars-2020-sample-return.html

It seems like there's a disconnect between the short time between now and 2026 and the complexity of the architecture. I suppose it's possible to start a multi-mission sample return before the architecture is finalized (and perhaps, in the form of the 2020 rover, we already have), but that seems a bit risky with the stakes and costs so high.

If the Mars Ascent Vehicle has no rover and relies upon an already-active rover to survive long enough to deliver samples to it, that simplifies the architecture enormously, but risks the failure of the rover before the MAV arrives. I suppose a simplicity-and-risk tradeoff is inevitable with something as big as this.

There has been on-going architectural studies and technology, for example paraffin-based fuels, for a sample return. Apparently NASA's managers think that an architecture could be chosen, technologies matured (a recent paper on paraffin fuels said the maturity was low), and the design and assembly completed by the mid-2020s. Without more details I'm skeptical.

A bigger issue may be what the overlapping development of three flagship-class missions -- Mars 2020, Europa Clipper, and Mars sample return, (ignoring a possible Europa lander) -- would do to the balance of the planetary science program. Topic for a near future post on my blog.

Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)