MSL FAQ - The pool of questions Options

[djellison]

Rob Manning and I swopped emails last night - and we think it might make sense to pool all the questions people have about MSL (and specifically MSL's EDL ) into one thread - and then answer as many as make sense either via a Q'n'A in the style of the previous ones I've done with Steve and Jim - or via Rob's typing fingers.

It'll be a few weeks till we sort this out - but submit-away until then

Doug

[elakdawalla]

Doug and I had the same idea -- he got to Rob first! -- but hopefully you'll also see Rob's responses in the future as a guest blogger.

Anyway, I'll start with one: in this post, Rob, you said:

(I have heard many a puzzled observer wonder why we are headed toward even more RubeGoldbergian designs. Rather than blame ever-cannonball polishing engineers like me, I would rather blame that frustrating Red planet that beckons us. Someday I will share the genesis of the Skycrane design concept - you might not be surprised that we conjured this - and other new designs in early 2000 in the wake of the MPL loss in late 1999.)

Please share!

Emily

[Juramike]

My Big list 'o Questions:

1) How scalable is this? How big (mass) a package could it deliver?
(Could you put down a future habitation module on Mars, deep drilling rigs, other cool stuff?)

2) Could you use it to put down multiple instruments in different (but fairly close, locations?)
[OK, you’d need to upgrade to more propellant, brains in the platform, and deal with COG issues]

3) Could you use it to move an instrument already on the surface to a new location?
[lotsa propellant, more brains in the platform, getting the rendezvous and “hook up” – but heck, the stability, lowering problems will already have been solved] (Imagine if we could send a Skycrane pick up Oppy and move her to another location within a 200 km radius – this would really change the post-Victoria discussion!)

4) Could it be used to deliver other packages down on other (airless) planetary surfaces?
[no chute, but using much, much more retro]? (Europa, for example).


5) Will it be possible to (exhaustively) test the Marscrane system on Earth before the big test on Mars?

-Mike

[akuo]

Ok, here is my question:

MSL is not limited by electrical power as much as previous rovers. The RTG will provide a constant current, though AFAIU batteries are still needed when power needs are higher.

Taking this into account, for how long time could MSL rove during a sol? Is it possible to move even during the night?

[Jim from NSF.com]

Ok, here is my question:

MSL is not limited by electrical power as much as previous rovers. The RTG will provide a constant current, though AFAIU batteries are still needed when power needs are higher.

Taking this into account, for how long time could MSL rove during a sol? Is it possible to move even during the night?

MSL operates off the batteries and the MMRTG recharges them. It will operate about 7 hours per sol

[Stu]

Apart from the obvious question that springs to mind after watching that new animation... "What were you guys smoking when you came up with the idea of the Skycrane?!?!?!?"... ... here are a couple, and apologies in advance if these have been answered elsewhere, but I can't remember reading the answers, and anyway, new people join UMSF all the time so these questions will be new to someone out there...

Will we be getting "video clips" from MSL?

In the light of the success of the "purely scenic" images taken during the NH Jupiter flyby, will MSL be programmed to take any similar images ("pretty pictures" as someone calls them... ) purely for Outreach value and media appeal? Maybe dedicated imagery of Earth-in-the-sky scenes? We (and by "we" I mean we frontline Outreach troops who spread the word) really need a classic, colour, "Earth in Mars'sky" image please, thank you...

How much more advanced will MSL's imaging instruments be than MER's?

Ta.

[djellison]

(and specifically MSL's EDL )

Although hopefully we could find someone to do those other questions.

[nprev]

Okay, I got two:

1. How exactly is the MSL/crane separation sequence initiated? Does MSL have something like aircraft "weight-on-wheel" switches that tell the computer it's down, and therefore safe to cut the cords?

2. Is the crane in fact commanded immediately at separation to do a tilt & escape maneuver as shown in the animation? (In other words, since I gather it has no brains of its own, how is it told to vamoose instead of possibly hovering right over MSL until it runs out of fuel...?)

[dvandorn]

And here's a few more to add to nprev's:

3) What happens if the rover touches down before the belaying lanyards have been fully extended? Especially what happens if one wheel of the rover hits a decent-sized rock before the lanyards have been fully extended?

4) Is the cable/lanyard separation accomplished via a signal in the lander (i.e., a contact sensor of some kind), or in the crane (a slack cable signal)? If it's a slack cable signal, can we be certain that any unexpected buffetting encountered by the rover won't accidentally set it off?

5) Are we certain there won't be enough engine blowback from the surface to set the rover into motion, perhaps so much motion it will tip over at wheels-down? Has the landing-on-a-slope case been considered in this regard, where a given slope (or even badly placed rock) could reflect engine exhaust in such a way as to destabilize the rover?

6) Has the general issue of slopes been addressed? What happens if the rover has a small but significant sideways motion at touchdown (due to substantial winds, I would guess) and that direction just happens to be downslope -- of a significant slope (like 20 degrees or more)?

7) Will MSL's obstacle avoidance capability be able to recognize slopes (hills and craters) as well as blocks?

OK -- I think that's enough for now -- . Thanks for being willing to address some of these questions, Rob!

-the other Doug

[Stu]

Although hopefully we could find someone to do those other questions.

Okay, okay, I didn't read the brief properly. Please file my questions until a more appropriate opportunity.

[Toma B]

Thanks Doug!
Here are my questions:

a ) Tests of Skycrane on Earth:

1 ) Is there a plan to do at least one full scale test of the descent stage using as close as possible to flight hardware?

2 ) When and where will these tests be undertaken?

3 ) Is there an almost finished Skycrane NOW somewhere in labs? (I don't intend to steel it :-))

b ) How long can it work once it is released from backshell?

1 ) How much fuel does it carry?

2 ) What is Skycranes thrust to weight ratio at full throttle?

3 ) At what height is Skycrane released from the backshell?

c ) How far away will Skycrane crash after releasing MSL-lander? (I know this cannot be answered precisely)

1 ) Is it possible that Skycrane will (almost) soft land?

2 ) Is there a plan to visit it after or is that for any reason dangerous?

Thanks again for the opportunity to do this? Sorry for my English.....

P.S.
I love this place....

[Eluchil]

Here are a few Rob might know the answers to:

1) When is the MARDI descent movie expected to be downlinked?

2) What on-orbit assests are expected to relay telemetry during EDL; can others be substituted if they are unavailible?

3) Are the testing facilities for the parachutes and whole EDL systems adequate or would full on upper atmospheric tests be useful?

Eluchil

[djellison]

There's a few questions that I think I can do a bit of an answer about for now:

Lots of the same question - full scale test of the whole thing. That's not even possible on Earth - that's what makes landing on Mars so hard - you can't practice. You can try and do a chute deployment on Earth using low wind speed at 1000 mbar - similar dynamic pressure to deploying on Mars - but it's not exactly the same. There was a RFP for a large rig to simulate the decent stage from which they would hang a mobility model to test software and the physical process ot touchdown - including slopes. You can test fire engines - you can simulate sloshing or other harmonic issues with pressurised water - but there's no way to simulate the whole thing...you just test systems as best you can - the simulate the system of systems virtually. VKG, MPF, MPL, MER, PHX - none had a full up system test of everything - because you just can't do it here.

MARDI movie will be downlinked.....after landing. Product downlink priorities for data to be taken in three years time - that's a bit premature isn't it I'm sure it will be something of a priority from a EPO perspective - but it'll be a big data product so it may take some time.

EDL comms will be to MRO and - if it's still around - Odyssey as well I would have thought - the same as Phoenix.

And here's the great thing about UHF, MRO and MSL ( and I'm hoping a DESCANO report on this - and the Phoenix one - will happen )

MER2Ody is 128k - or 256k if it's a good pass - typically 10-15 minutes - 50 to 150 Mbits in a pass.

MSL2MRO can be up to 2048k - shorter on average than MER passes with Odyssey - but still potentially up to 1000 Mbits or more in a pass.

Doug

[helvick]

I presume you mean MSL2MRO there.

[djellison]

Yeah - that what I said.



Cough ahem oops well spotted.


Doug

[DEChengst]

Looking at it from an artistic point of view:

Is there any chance of MastCam tracking and making a movie as the Skycrane flies away, although the mast probably will still be stowed on the rover's deck ?

[ElkGroveDan]

Once science is well on the way, are there any plans for examination and study of the EDL hardware?

[djellison]

Is there any chance of MastCam tracking and making a movie as the Skycrane flies away, although the mast probably will still be stowed on the rover's deck ?

I would hope that the optics would be orientated so that they would be well out of the way of any rocket exhaust at fly-away.

Doug

[nprev]

Is there any chance of MastCam tracking and making a movie as the Skycrane flies away, although the mast probably will still be stowed on the rover's deck ?

In addition to Doug's observation about protecting the optics, from a risk mitigation standpoint it would be unwise to burden the flight software with a non-essential requirement so quickly after one of the most critical events of the entire mission. MSL's got to get its act together afterwards, we don't need to take a chance on incurring the equivalent of a 'blue screen of death' . (Don't get me wrong, though, DE; I'd really love to see that myself! )

[djellison]

This skycrane/decent stage debate is ending. Now. We've had it before. We're going in circles. Stop. Now. This is a thread for questions about MSL's EDL - not the semantics of naming.

Multiple posts deleted.

Doug

[mcaplinger]

Will we be getting "video clips" from MSL?

That's a downlinked data volume question; the hardware can certainly do it at up to 10 fps. Of course, nothing much is moving at rates that would justify a frame rate that high; the team is still considering this. (And no, we can't see the descent stage fly away; Mastcam and MAHLI are still turned off and stowed, and MARDI is pointed down.)

Maybe dedicated imagery of Earth-in-the-sky scenes?

I'm certain we'll try this, but we only have 100 mm focal length, so I'm not sure the disk will even be resolved; it'll still just be a blue dot.

How much more advanced will MSL's imaging instruments be than MER's?

I'm not sure how to quantify "more advanced." They're about 100x faster with about the same noise performance. The MER cameras were all fixed-focus. Mastcam has a 10:1 zoom lens with autofocus. MAHLI (the MI equivalent) has adjustable focus with autofocus. All the instruments are capable of realtime image compression and other internal image processing and have 8 GB flash buffers for data storage. They can all take Bayer-pattern color images with one frame (some might call that less advanced than multiple exposures through color filters, but Mastcam can do that too.) On the other hand, they weigh more and are a lot more mechanically complex, which I can assure you is a development challenge.

[Guest_Sunspot_*]

Malin Space Science Systems has information on some of the cameras they are building:

http://www.msss.com/msl/mastcam/index.html
http://www.msss.com/msl/mahli/index.html
http://www.msss.com/msl/mardi/index.html

# Each Mast Camera has a 10x telephoto/zoom capability; the field of view (FOV) can be from 6°(zoomed) to 60° (not zoomed).

# Near the rover, Mastcam images have a spatial resolution of about 150 micrometers per pixel. With the telephoto system, objects at 1 kilometer distance can be resolved at 10 centimeters per pixel.

[djellison]

Here's one for you Mike - I get bayer filters - and I get the normal way of doing filtered obs. How do you set up a CCD to do single shot colour but ALSO do filtered obs as well? Is it like a hybrid bayer filter that has an R, a B but only one G with what would be the 'other' G as a clear for use with filters? (That's a complete and utter guess)

Doug

[nprev]

Nice, you guys; sounds like some exciting pics are pending!

Truly off-the-wall Skycrane question here: How much hydrazine is expected to remain in its propellant tanks after a nominal descent? Reason I ask is that if (a big if, admittedly) the tank(s) rupture after impact, it might be interesting for MSL to cautiously approach the wreckage at a safe distance a few sols later in order to take a few spectra of any obviously NH4-'splashed' soil to see what sort of reaction compounds may have formed... a unique opportunity for understanding local minerology if it presents itself and is safe to pursue.

[Jim from NSF.com]

The amount of fuel in the DESCENT STAGE should be only vapors if the fly away manuver is "successful"

[nprev]

Ah. So, then, the descent stage is expected to stay airborne until it runs out of fuel, Jim? That seems to place some topographical constraints on the landing site; maybe the landing site slope question is moot.

[Jim from NSF.com]

Not really, the flyout is independent of landing site slope. Anyways the slope is going to be minor, if any

[nprev]

I see; thanks! I was wondering about some of the candidate clay-bearing sites in canyons, which apparently have fallen off the target list; wouldn't do for the descent stage to bash into a canyon wall & blow up too close to MSL...

[mcaplinger]

Here's one for you Mike - I get bayer filters - and I get the normal way of doing filtered obs. How do you set up a CCD to do single shot colour but ALSO do filtered obs as well? Is it like a hybrid bayer filter that has an R, a B but only one G with what would be the 'other' G as a clear for use with filters? (That's a complete and utter guess)

That might work well, but we use an off-the-shelf sensor so we can't have a custom filter. No, the narrowband filters work because the Bayer filters are transparent in the near-IR, where the narrowband color can be used to look for iron-bearing minerals. In the visible, there is always some overlap between the narrowband filter and at least one of the three Bayer filters, often two. In those cases we just adjust the interpolation appropriately to use only the pixels that have usable signal after light has passed through both the Bayer and narrowband filters.

[djellison]

Ahh - suddenly it all becomes clear(er) - cheers Mike

Doug

[climber]

Question for both Phoenix and MSL : what kind of colour-target / sundial will we have ?

As it's gona be the most targeted target....

[mcaplinger]

Question for both Phoenix and MSL : what kind of colour-target / sundial will we have ?

Phoenix cal target: http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1149.pdf

MSL cal target is still being designed.

[monitorlizard]

Given the power output of MSL's RTG and the best model you have of rate of power output decline due to plutonium decay, how long could the RTG provide enough power to keep MSL roving (assuming nothing else failed)? Thanks.

[Thu]

I have some questions:

1. What is the ratio of final mass delivered (the rover) and entry mass at Martian atmosphere for the two methods: SkyCrane and airbag delivery method on Mars?
I'm expecting SkyCrane to have better efficiency than using airbag but could anybody give me some specific numbers for comparison?

2. I remember reading somewhere that MSL will be equipped with a flashlight that will allow it to move or perform some science observations at night. Is this true and what's the advantages for observing in the dark on Mars?

3. Another question, maybe a stupid one: Did engineers find out what went wrong with Spirit's right front wheel and come up with an upgrade for MSL's wheels? Or should we let it happens because who knows a dragging wheel may lead to an unexpected discovery

4. Thinking of the 3rd question, I come up with this last one: if something bad forces MSL to move backward just as Spirit is doing now, I think it'll be more difficult for MSL's computer to navigate because her camera mast is not at the center as her sister's. How do you think about this?

Thanks,

[mcaplinger]

2. I remember reading somewhere that MSL will be equipped with a flashlight that will allow it to move or perform some science observations at night. Is this true and what's the advantages for observing in the dark on Mars?

http://www.msss.com/msl/mahli/MAHLI_description.html

"MAHLI has a suite of white light LEDs and a suite of ultraviolet LEDs to provide illumination of the targets it is imaging. The white light LEDs permit the instrument to operate at night and allows the science team to avoid problems of shadowing during daytime imaging. The ultraviolet LEDs provide an opportunity to look for minerals that fluoresce."

[remcook]

If you've got an RTG you might as well do nighttime observations. So, I guess science of MSL is limited by data rates, not power?

[centsworth_II]

MSL operates off the batteries and the MMRTG recharges them. It will operate about 7 hours per sol

How fixed is this seven hour figure? Is it a maximum? An average? And what does "operate" mean?
The MERs routinely "operate" their spectrometers for 12, 24 or more hours at a time.

[elakdawalla]

Here's a few that I've received by email. The first two are variations on a theme:

What kind of AI, if any, is built into the descent stage in terms of selecting an exact point to set the rover down? In other words, does the sky crane "look around" for a suitable spot as it descends, or does it just go straight down regardless?

Is it the rover or the descent stage that decides when the rover is safe on the ground? I'm guessing they both need to know when touch-down occurs because, from the video, it looks like the rover releases the cables and the descent stage flies clear of the rover. So do they both detect it? Or does one detect it and communicate to the other? How is detection done? Radar? Touch sensor?

Why is the "skycrane" concept better than just lowering the rover to the ground with retrorockets (as if using zero-length cables)? Are the cables used for cushioning? Wouldn't it be better for the "skycrane" to hover in one place and lower the rover by unwinding the cables very slowly till the rover touches down, rather than descending with the cables fully extended, as in the video?

[Jim from NSF.com]

How fixed is this seven hour figure? Is it a maximum? An average? And what does "operate" mean?
The MERs routinely "operate" their spectrometers for 12, 24 or more hours at a time.

Operate = rove

If you've got an RTG you might as well do nighttime observations. So, I guess science of MSL is limited by data rates, not power?

limited by power

[Jim from NSF.com]

1. Why is the "skycrane" concept better than just lowering the rover to the ground with retrorockets (as if using zero-length cables)? Are the cables used for cushioning? Wouldn't it be better for the "skycrane" to hover in one place and lower the rover by unwinding the cables very slowly till the rover touches down, rather than descending with the cables fully extended, as in the video?

Skycrane concept eliminates thruster plumes and dust on the rover

The mobility system (wheels etc) absorb the shock

no, extended hover is harder to maintain

[Alex Chapman]

I know it’s a little off topic but I have a quick question about something I saw on the animation post EDL. The animation shows a sample being loaded into, what I asume is, one of the sample holders in the Chemistry & Mineralogy X-Ray Diffraction (Chemin) instrument. From what I can see it looks like there is 24 or so separate sample holders and I was wondering if each holder only be used once and so limiting the number of samples analysed by Chemin.

Do the instruments within the Sample Analysis at Mars Instrument Suite (SAM) have similar limitations on the number of samples that can be studied? Just one last thing, why does Sam have two sample entry ports on the rover’s deck?

Thanks

[Jim from NSF.com]

SAM is being redesigned at the moment

[Cugel]

Skycrane concept eliminates thruster plumes and dust on the rover

Would that be a problem when there is no solar panel up there?
I believe the big advantage of the skycrane is that it minimizes the mass that actually lands.
And by doing so it reduces the stress and loads caused by touchdown.

The mobility system (wheels etc) absorb the shock

I don't think a rocker-bogie system does much shock absorbing as it is completely rigid.
This simply means the vertical speed at touch down must be very small.

BTW, I'm much more concerned about horizontal speed at landing than about vertical speed, which is much more easy to control. I'm afraid the suspension system will not have much tolerance for horizontal speed at touchdown and any swinging motion of the rover must be dampened by the skycrane. Or does the rover have any reaction control system of its own? (I don't think so, as it doesn't carry any fuel tanks).
This will be a pretty tough control job in the windy Martian atmosphere and coming from a huge horizontal entry speed.

[centsworth_II]

Hold a Yo Yo by the string. With a few cm of string, the Yo Yo swings wildly
when the string is shaken back and forth. As the string is lengthened, the
swinging becomes less. When the string is sufficiently long, it can be moved
back and forth quite a bit with little or no motion of the Yo Yo.

[tty]

Would that be a problem when there is no solar panel up there?

Rocket plumes are always a problem close to the ground and they start impinging on it. Not only do they raise dust, but if the ground is uneven you can get quite difficult control problems. Back in the forties they experimented a great deal with using retrorockets to airland loads without parachutes. It worked quite well right until the rockets started impinging on the ground. Then the load invariably turned over.

[Jim from NSF.com]

Would that be a problem when there is no solar panel up there?
I believe the big advantage of the skycrane is that it minimizes the mass that actually lands.
And by doing so it reduces the stress and loads caused by touchdown.
I don't think a rocker-bogie system does much shock absorbing as it is completely rigid.
This simply means the vertical speed at touch down must be very small.

BTW, I'm much more concerned about horizontal speed at landing than about vertical speed, which is much more easy to control. I'm afraid the suspension system will not have much tolerance for horizontal speed at touchdown and any swinging motion of the rover must be dampened by the skycrane. Or does the rover have any reaction control system of its own? (I don't think so, as it doesn't carry any fuel tanks).
This will be a pretty tough control job in the windy Martian atmosphere and coming from a huge horizontal entry speed.

The dust and the effluents from the thrusters would contaminate the rover

there is no "huge" horizontal velocity, it is coming vertical by the time the rover is repelling

[Cugel]

there is no "huge" horizontal velocity, it is coming vertical by the time the rover is repelling

I stand corrected on that one.

[Pertinax]

http://www.msss.com/msl/mahli/MAHLI_description.html

"MAHLI has a suite of white light LEDs ..."

I would presume that this would also be useful in further constraining 'true color' as we will be able to view an object under both under daylight conditions and under a fully understood source of illumination.

BTW, what is the spectrum of the white light LED' in MAHLI?


-- Pertinax

[mcaplinger]

I would presume that this would also be useful in further constraining 'true color' as we will be able to view an object under both under daylight conditions and under a fully understood source of illumination.

To an extent, but the LEDs are not intended to be calibrated light sources and there is likely to be some color shift as a function of current and temperature. White LEDs typically have a narrow peak in the blue where the LED actually emits, and then a broader peak centered in the yellow where the phosphor emits; see http://en.wikipedia.org/wiki/LED

[Pertinax]

Thank you.

I didn't know if there were any other kinds of white LED (the kind you describe being the only sort I was aware of, though I am far, far from being an LED expert ).

-- Pertinax

[MarsEngineer]

Holy smokes! I leave you folks for a few days and when I come back I find a ton of (excellent) questions!

I apologize in advance in my tardiness. I have read both the questions and the responses of others (so far) and I am looking forward to making a stab at satisfying your curiousity (and if you are like me, your curiousity may never end!)

I am swamped this past week and much of next so I may have little chance to pop in (Phoenix & MSL reviews), but I will try to find moments here and there.

Just a quick note. Doug, I know that the naming story is getting old, but I did promise here that I would ask Adam about the naming conventions.

He made it clear to me that the words that they are allowed to use for copyright reasons is "sky crane" (not Sikorsky's Skycrane). I will have to remember that. And yes, the new captioned animation at JPL's site incorrectly identified the descent stage as the "sky crane". The MSL EDL gang had not seen the animation. We may have to make a rev B.
Finally the word "lander" is never used to describe MSL equipment by the MSL gang.

Those of you who are taking a stab at answering questions are doing a great job ! (It is especially nice that Mike C is here to help too. I know little about the MSL cameras.)

-Rob

[nprev]

Hey, Rob! Thanks for the update. (Surprising how the devil is always in the details for even the smallest things like the naming of names...<clink exp 40> lawyers. ) Appreciate the effort to answer this firestorm of questions, but please take your time; we all know you have much much more important things to do!

My big concern is touchdown/separation event sequencing. Based on dvandorn's previous questions, it seems like the fail-safe approach would be to receive weight-on-wheels inputs from at least three squat switch sensors for a fixed, albeit brief period--0.5 sec?-- (and at least one of said inputs from an opposing side of MSL) before cutting the bridles. This would ensure parallel ground placement and hopefully wash out spurious 'jerk' switch actuations from other events such as parachute deployment and 'sky_crane' engine max thrust during deceleration.

[Jim from NSF.com]

There are some "major" changes to the sample handling gear. Most has be moved to the turrent at the end of the arm. Corer is out and replaced by powdering drill.

some minor changes to EDL such as mobility system deployment during repel

[Guest_Geographer_*]

Why not have two rovers like MER? Double the science with less cost per rover and probably twice the chance at least one rover lands correctly.

[djellison]

Because the money isn't there to do it. MER was initially $440m for one - approx $625m for two - which grew to about $850m by launch. One MSL is looking like being $1.5B - so on the estimated 'second is 50% extra' formula - another $750M would have to be found, and given the state of Space Science at the moment...that's just not going to happen.

[Toma B]

I'm just curious ,how much would MER cost now that they know how to build it , presumably they would not change a single thing.

[djellison]

Well - when I spoke to Squyres back in the autumn of '05 - I asked if a MER vehicle could be built for a Mars Scout budget - and he said probably not. That would put it at at least >$400m

Because it's been nearly 4 years since ATLO started for MER - there would be not a lot of saving to be had from the heritage - perhaps the orig. single vehicle budget of $440m could be matched (which was initially exceeded because of the 'chute, airbag and other changes from pathfinder 'heritage' )

I would imagine there are a few things they would want to change. More efficient solar cells being one I would guess. I'm sure there are flight ready systems that could be used as metaphorical upgrades. Given you would be building from scratch, there's no point in sticking to exactly the same design for everything because you're going to have to test the new hardware just as much as the old stuff was tested 4 or 5 years before. It would make sense, where the changes are modest, to make any changes that could improve reliability or performance.

Reuse of the MER deisgn in some form has been touted as a potential mission for the future - 2013/15 sort of time frame - but it's only one of multiple options out at that distance.

Doug

[dvandorn]

I will also point out, in regards re-using the MER design, that while a "quiet" Mars can support a solar-powered rover for multiple Martian years, a single global dust storm could easily kill them. And such global dust storms aren't only possible, they're inevitable. We've been somewhat lucky that the MERs have been operating under optimum dust conditions, overall. Even the small dust storms that have popped up have managed to avoid directly impacting either landing site.

I'm just saying that even though the MERs have lasted a very long time, don't make the mistake of assuming you can re-fly the same (or similar) design and be assured two or three Martian years of lifetime. The baseline mission of a MER rover is 90 sols, and even with an upgrade, I don't see that changing a whole lot...

-the other Doug

[Guest_Geographer_*]

Thanks djellison, I had no idea MSL is costing that much! Is the extra cost primarily in testing our new technologies like the sky crane landing system? Or does the nuclear powerplant cost some obscene amount?

[helvick]

An RTG of the type MSL will use costs in the region of $50-$75m. The plutonium itself costs about $3k-$4k per gramme and MSL's unit will get about 4kg to produce around 110w of continuous power. So to answer your question most of the cost is elsewhere although the RTG isn't cheap.

[Jim from NSF.com]

B)-->

I'm just curious ,how much would MER cost now that they know how to build it , presumably they would not change a single thing.
[/quote]


The launch vehicle would have to be different. 2003 was the only time frame a Delta II could perform the mission

[Jim from NSF.com]

An RTG of the type MSL will use costs in the region of $50-$75m. The plutonium itself costs about $3k-$4k per gramme and MSL's unit will get about 4kg to produce around 110w of continuous power. So to answer your question most of the cost is elsewhere although the RTG isn't cheap.

Actually there are more costs due to the MMRTG.
1. MSL is contributing money for the development of it
2. There are launch vehicle mods
3. there are launch approval costs
4. there are launch processing costs

[nprev]

The launch vehicle would have to be different. 2003 was the only time frame a Delta II could perform the mission

True; close oppositions of Mars only happen every 17 years, so the next such opportunity (ta-dah, dah!) won't be until 2020.

[Guest_AlexBlackwell_*]

The launch vehicle would have to be different. 2003 was the only time frame a Delta II could perform the mission

Wasn't Delta II possible in 2005 and/or 2007 with a Venus and/or Earth gravity assist?

[Jim from NSF.com]

The vehicles weren't design for that. Per Peter T., it was 2003 or the NASM

[Guest_AlexBlackwell_*]

I know MER wasn't designed for that; the assumption was that the spacecraft would be modified for inner solar system cruise. My understanding is that there was trajectory analysis done that identified an Earth and/or Venus gravity assist for either the '03 or '05 launch opportunities.

Whether it was feasible is another issue, but assuming it was, then Delta II could have handled it.

[hendric]

Rob,
How is MSL going to keep the sand out of its wheels? I noticed in the pictures from Emily that there wasn't much of a guard on the sides of the wheels to keep out sand and rocks.

[PhilHorzempa]

Rob,

There is a thread here at UMSF discussing possible names for MSL. I know
that you have no control over the naming of MSL (isn't that a shame?), and
that someone over in NASA HQ will decide. Here are my questions -

1. Can you let us at UMSF know who that bureaucrat is and how we
can contact him/her?

2. Do you have any favorite name, or names, for MSL?

3. Is there a "pet" name for MSL at JPL?

4. Have you heard other names suggested by JPL engineers?


I know that these are not technical questions, but I still think that they are important.
Names go a long way in helping the public identify with a mission.
Imagine if, instead of Stardust, the comet mission was named Flypaper-1.

Also, I am tired of the "let the school kids name the mission" trend.
I would rather have the project team name the project.
If that isn't allowed, how about opening up a naming program on the Internet,
open to Everyone, including adults and school kids. If you get a million suggestions,
then count your blessings in that amount of public interest. If that happens, pick
a thousand out randomly, have someone read all of those, and pick 10 finalists.
Then let the American Idol crowd vote for their favorite.

Another Phil

[Jim from NSF.com]

Rob,

There is a thread here at UMSF discussing possible names for MSL. I know
that you have no control over the naming of MSL (isn't that a shame?), and
that someone over in NASA HQ will decide. Here are my questions -

1. Can you let us at UMSF know who that bureaucrat is and how we
can contact him/her?

Mike Griffin and I am not joking

[mcaplinger]

2. Do you have any favorite name, or names, for MSL?

3. Is there a "pet" name for MSL at JPL?

4. Have you heard other names suggested by JPL engineers?

I can't speak for Rob or anybody at JPL, but I have never, ever heard any name for the vehicle other than MSL. JPL has never been big on "pretty names" for spacecraft: witness Mariner 9, Viking 2, etc. It's only been fairly recently that names started being used (Galileo and Magellan were the first I recall, obviously when you only have one spacecraft per mission type you can't use a number) and even then, those programs were often referred to as Jupiter Orbiter/Probe and Venus Radar Mapper, respectively. I will always think of Mars Climate Orbiter and Mars Polar Lander as the Mars Surveyor 1998 Orbiter and Lander; the names (pretty lame in that case) usually come very late in the process. There are plenty of people who still call Spirit and Opportunity MER-A and MER-B (or MER-2 and MER-1

Sometimes the assembly techs have pet names for spacecraft, but they're not always printable :-)

[Jim from NSF.com]

There are plenty of people who still call Spirit and Opportunity MER-A and MER-B

Include me in this group

[Oren Iishi]

Well - when I spoke to Squyres back in the autumn of '05 - I asked if a MER vehicle could be built for a Mars Scout budget - and he said probably not. That would put it at at least >$400m

Because it's been nearly 4 years since ATLO started for MER - there would be not a lot of saving to be had from the heritage - perhaps the orig. single vehicle budget of $440m could be matched (which was initially exceeded because of the 'chute, airbag and other changes from pathfinder 'heritage' )

I would imagine there are a few things they would want to change. More efficient solar cells being one I would guess. I'm sure there are flight ready systems that could be used as metaphorical upgrades. Given you would be building from scratch, there's no point in sticking to exactly the same design for everything because you're going to have to test the new hardware just as much as the old stuff was tested 4 or 5 years before. It would make sense, where the changes are modest, to make any changes that could improve reliability or performance.

Reuse of the MER deisgn in some form has been touted as a potential mission for the future - 2013/15 sort of time frame - but it's only one of multiple options out at that distance.

Doug

I can't understand why the MER test rover couldn't be modified and used in a future Mars mission. I'm sure that the test rover hasn't gone through the rigorous space qualification processes of the other two rovers but its basic structure should be the same. I would think that it would cost maybe a tenth the cost of a new rover. It could be made better than the original rovers (as you stated) by adding better solar arrays, software and etc.

http://www.nasa.gov/vision/universe/solars...mer-050606.html

[Jim from NSF.com]

Because it has be used over and over in the Mars yard. All the parts would need to be clean and requalified.It has no brains. There is no lander or cruise stage, so it doesn't really save any money

[ElkGroveDan]

Mike Griffin and I am not joking

Well that's interesting. What makes you think it's just him?

[Jim from NSF.com]

Because the Admin has the final say.

As for bureaucrats, involved: Alan Stern, Doug Mcquistion (sp?) Mars program executive,

[gallen_53]

Sometimes the assembly techs have pet names for spacecraft, but they're not always printable :-)

I've been told that the original in-house names for MER-A and B were Itchy and Scratchy. IMHO, those names would have been better than the lame ones actually used.

[djellison]

Oh - I heard other names got used once or twice given the months of 50,60,70+ hour weeks involved.

[mchan]

Those got mentioned here. Divorce was one, can't remember the others.

[MarsEngineer]

Rob,
How is MSL going to keep the sand out of its wheels? I noticed in the pictures from Emily that there wasn't much of a guard on the sides of the wheels to keep out sand and rocks.

Hi Hendric,

I do not know the answer. My first take on the matter is that it looks like the wheel design is tolerant to rocks and sand entering the wheel cavity as MER was intended (but ultimately, it turned out not not to be). You will recall that MER had a bit of a challenge with potato-sized rocks getting stuck between the inner wall of the wheel and the axel. The spacing on MSL's design is much larger (should we worry about eggplant sized rocks?). But I will ask the mobility team's lead engineers Jaime and Chris. They may yet want to close out the gaps as was done with the fill material and kapton used on MER. There is still time.

thanks!

-Rob

[MarsEngineer]

I can't speak for Rob or anybody at JPL, but I have never, ever heard any name for the vehicle other than MSL. JPL has never been big on "pretty names" for spacecraft: witness Mariner 9, Viking 2, etc. It's only been fairly recently that names started being used (Galileo and Magellan were the first I recall, obviously when you only have one spacecraft per mission type you can't use a number) and even then, those programs were often referred to as Jupiter Orbiter/Probe and Venus Radar Mapper, respectively. I will always think of Mars Climate Orbiter and Mars Polar Lander as the Mars Surveyor 1998 Orbiter and Lander; the names (pretty lame in that case) usually come very late in the process. There are plenty of people who still call Spirit and Opportunity MER-A and MER-B (or MER-2 and MER-1

Sometimes the assembly techs have pet names for spacecraft, but they're not always printable :-)

You are right Mike. For reasons that probably lurk deep in the neuronal structure of us Dilbert-like engineers we find ourselves quickly getting comfortable with TLAs (three letter acronyms). MSL runs off our lips as loquaciously as VCR, EDL, PC and iPhone.

I have to agree that it is odd, but we really did not have special names for the two rovers under construction in ATLO (assembly, test & launch ops) during late 2002 and 2003 other than MER-1 & MER-2. We are a dull lot aren't we?

We did have unique names for some of our hardware that we used in jest. One particular "flight" rover's electronics module (REM) was put through its test paces inside inside a thermal chamber (hot & cold) where we had inadverantly let in ambient (not dry) air after it had been cold. The result was a soaking wet set of very expensive electronics. Forever after we called it the incredible "Aqua REM". This same REM took a turn on (I think) MER-1 / Opportunity and found iteslf getting zapped on an AC outlet by accident. We decided that neither rain nor sleet nor electircal shock would hinder that REM. It worked fine but we still decided it would be best it remained on mother earth. It still lives in the testbed.

When I first started working JPL (as a student electronics draftsman), I worked on what was still called "JOP" or Jupiter Orbiter Probe. It was renamed Gallieo soon just after I arrived around 1980 (it was scheduled to be launched in '83 or '84 by then I think). It took us a while to get used to "Gallieo". Some folks really did not like it, but we got used to it.

Unlike competed missions (like Phoenix which get named by their PIs) these big missions tend to get their final mission names relatively close to launch. Even Spitzer was SIRTF (Spaceborn InfraRed Telecscope Facility) prior to launch. I do not know the reason but I think it has to do with "reality". Even up to the weeks before launch there is some (low) probability that these machines will not be launched. Once the are really really going to launch, then a final name is selected.

-Rob

[David]

I do not know the reason but I think it has to do with "reality". Even up to the weeks before launch there is some (low) probability that these machines will not be launched. Once the are really really going to launch, then a final name is selected.

The Soviets did y'all one better, not naming their spacecraft until after launch; that is, if they were successful; if they failed they got some dud placeholder name like "Kosmos".

[climber]

When I first started working JPL (as a student electronics draftsman), I worked on what was still called "JOP" or Jupiter Orbiter Probe. It was renamed Gallieo soon just after I arrived around 1980 (it was scheduled to be launched in '83 or '84 by then I think). It took us a while to get used to "Gallieo". Some folks really did not like it, but we got used to it.
-Rob

I like this one Rob, you're still NOT used to it . It was called GALILEO and not Gallieo

[Jim from NSF.com]

The Soviets did y'all one better, not naming their spacecraft until after launch; that is, if they were successful; if they failed they got some dud placeholder name like "Kosmos".

Not really. They all had names, just not public ones

[Stephen]

There are plenty of people who still call Spirit and Opportunity MER-A and MER-B (or MER-2 and MER-1

I'm going to go out on a limb here and say that lame as they may be, and despite being wary of them initially myself, I've kinda grown comfortable with the names "Spirit" and "Opportunity", just as most seem to have grown comfortable with other names for other NASA spacecraft--like "Hubble", "Sojourner", "Magellan" and "Voyager" (the last, BTW, if memory serves, started out in life being called "Mariner Jupiter/Saturn" before being renamed; I wonder how many diehards at NASA or JPL still call them that?

In some senses "Spirit" and "Opportunity" even, bizarrely, reflect the rovers' respective fates (with "Opportunity" have more than its fair share of luck--eg its hole-in--one in Eagle Crater--and Spirit of pluck).

But that said others have not gone down so well. Does anybody--except maybe NASA's PR office--habitually refer to the Mars Pathfinder lander as the "Carl Sagan Memorial Station"? Or the Viking 1 lander as the "Thomas A. Mutch Memorial Station"?

For that matter who would refer to certain (other) pieces of MER hardware as the "Columbia Memorial Station" or the "Challenger Memorial Station"?

I guess in the end it all comes down to what we feel most comfortable with, have grown used to, or find trips most easily off the tongue.

======
Stephen

[Toma B]

I'm little impatient...
When is "Rob Manning Q'n'A" coming up?

[djellison]

Plan is for me to pull all the questions together - hand them to Rob, and Rob will do written answers.

BUT

I'm not giving Rob the questions till after Phoenix is away I'm not going to get the blame if Phoenix has EDL issues.

My advice - forget it was ever thought of, and then it'll be a nice suprise when Rob starts answering the questions

Doug

[dvandorn]

"Voyager" ... BTW, if memory serves, started out in life being called "Mariner Jupiter/Saturn" before being renamed; I wonder how many diehards at NASA or JPL still call them that?

I may be misremembering, but I have this vagrant memory that, at one point, they were referred to by the mission name Mariner Outer Planets Explorer. I also have a vagrant memory that they were renamed quickly after that, since no one wanted to fly a MOPE...

-the other Doug

[lyford]

All that MARDI talk over on the Phoenix thread got me to a thinkin':

Can the MARDI also be used to image the ground beneath MSL like Phoenix? Would this be helpful in any way to detect slippage? Or what other "stop you're in another Purgatory Dune" mechanisms are there?

[monitorlizard]

Some may feel this belongs in the Mars Sample Return thread, but my main question is about MSL. The July 9 Aviation Week has an article about Alan Stern wanting to move up a sample return mission to 2018/20, with the following quote:

"One approach may be to outfit the '09 MSL...with a sample cache that could be filled as the rover moves across the surface and retrieved by a later sample return mission."

Is this really possible, given how close MSL is to launch? It was my impression that the MSL design is pretty close to being frozen, and adding a sample cache seems to involve a nontrivial change to the rover design. I'll admit it could be done on an emergency basis, but given the budget problems MSL has already incurred, the schedule is currently very tight. I don't see how it could be done without restructuring the MSL program and delaying launch to 2011.

I applaud Dr. Stern wanting to shake things up a bit and challenge the Mars program, but this doesn't seem realistic.

[nprev]

Agreed, Monitor. However, that sounds like a potentially valuable standard feature to add to any and all future rovers. It would be great to carry along significant samples for possible later return or more detailed examination, whether by MSR or eventual manned missions...saves a lot of footwork for the latter!

Of course, the science team would have to be pretty selective...I can just see Spirit & Oppy hauling around about 500 kg of rocks each after traveling only 1000 meters or so...

[Jim from NSF.com]

Close to launch? CDR just happened and the sample handling portion was delayed until Oct

[lyford]

Of course, the science team would have to be pretty selective...I can just see Spirit & Oppy hauling around about 500 kg of rocks each after traveling only 1000 meters or so...

Shades of The Long, Long Trailer...

...a honeymoon journey fraught with tilted axles and Lucy's ill-advised collection of large souvenir rocks.

But we would have a good name for the rover - Lucy!

[edstrick]

"...science team would have to be pretty selective..."

Doesn't take much.. imagine pencil-erasor sized grabs of soil or other "fines" and centimeter long pencil-thick minicores of rock. You can do incredibly lots with that.. each would more than everythign brought back from stardust.

[monitorlizard]

Instead of "close to launch" I probably should have said "so far along in the development cycle". What I was getting at is that MSL is not very receptive to adding major new features at this point. The volume of the rover has been split amongst the various systems and experiments, and adding a sample cache system now would mean moving a lot of things around, especially considering the cache location would be constrained by where the sample delivery system arm could reach.

I actually like the idea of adding sample caches to future rovers like ExoMars and the astrobiology rover, but I think it's too late for MSL unless a major funding increase is imminent.

[monitorlizard]

The great thing about this forum is that the interaction inspires creative juices to flow. My biggest talent is contradicting myself, and I just thought of something about a sample cache system for MSL. Not knowing a great deal of the rover's technical design, I'm still wondering if you could put a sample carousel on the side of the vehicle, oriented vertically (like a ferris wheel), with sealing chambers and a rotation of the carousel after each sample was deposited. Such a design wouldn't require moving other rover systems around, provided that a slight increase in the width of the rover were allowable and the sample delivery arm could reach that location.

I dunno, does this sound logical?

[Jim from NSF.com]

As of now, it is going to be a horizontal carousel and placed in the front

[Phil Stooke]

odoug: "I may be misremembering, but I have this vagrant memory that, at one point, they were referred to by the mission name Mariner Outer Planets Explorer. I also have a vagrant memory that they were renamed quickly after that, since no one wanted to fly a MOPE..."


I think you mean TOPS - Thermoelectric outer planet spacecraft.

Phil

[nprev]

.. imagine pencil-erasor sized grabs of soil or other "fines" and centimeter long pencil-thick minicores of rock.

Yeah..I like it, I like it! Design such a system for all future rovers, and future human expeditions could conceivably acquire excellent mineralogical profiles for entire regions while minimizing in situ routine sample runs, enabling them to concentrate on interesting things they'd find in real time instead of baseline stuff.

I love it when a plan comes together!

[edstrick]

There was a very very good general review of the TOPS mission proposal in one of the space-aeronautics journals when it was under concept development --- before the no-funding decision and budgetary de-scoping of the mission concept to Mariner Jupiter-Saturn.

I *THINK* it was Astronautics and Aeronautics, but it may have been in Space-Aeronautics. Good engineering libraries should have bound copies. It would be about 1972? 1973?.. not much later than that.

[mchan]

I do recall reading the Astronautics and Aeronautics article. Before the descoping, the spacecraft were to be designed for longer minimum mission lifetimes. One spacecraft was targeted to same planets that Voyager 2 eventually encountered. The other was targeted Jupiter -> Saturn -> Pluto.