Stationary Lander @ Meridiani - one of the first questions I asked SS last autumn

Doug

http://history.nasa.gov/SP-4212/ch9.html has some background on this. It doesn't look to me like anything in the area was considered. Remember that prior to the MGS TES hematite observations, there was nothing that special about Meridiani.

Well, in 1976 I think that the quite terrestrial appearance of Meridiani would have had a lot more general PR appeal...even better if VL1 would have landed close to one of the frequent sedimentary outcrops, especially if a few mysterious blueberries were visible! The berries alone would have really captured the public's imagination at that time. The "rocky wasteland" stereotype of Mars from the Viking sites impaired public interest, especially because the views from both landers were so similar.

Re rockiness: Don't forget that VL1 was only ten feet or so from Big Joe, and VL2 had a significant rock quite nearby as well...hitting those things would have been game over...no comparison at all to the safety of Meridiani for the Viking design, and in fact they were expecting a smooth sandy plain at Chryse, if I recall correctly.

Still makes me wonder why Meridiani wasn't in play at all, or even Gusev for that matter...Spirit's landing site was also much smoother than Chryse or Utopia.

...thanks for the link; a fascinating story! I am definitely not criticizing the Viking team at all, BTW; understand fully how little information they had to work with to formulate these decisions.

Looks like the emphasis was on finding the best hope of liquid water by latitude. Too bad Hellas was dropped off the list for VL2, though; I suspect that's a really interesting place...

A lot of pre-Viking artwork depicted the landing sites as appearing a lot more
like Meridiani's dune fields than the boulder-strewn ones they actually came
down upon.

See Don Dixon's artwork for an example:

http://www.cosmographica.com/gallery/portf...io051/index.htm

Mars Pathfinder and even Spirit initially did little to dispell the idea that
much of Mars was covered with boulders.

Besides, the selection of the Chryse Plantia and Isidis Plantia were made when the Vikings orbiters were looping around Mars looking for the best places to land! That was a fast decision. Otherwise, the selection of places for MER might be done when MER Spacecraft were cruising toward the Mars. For Spirit, the potential places where : Isidis Plantia, Hematite, Melas Chasma and Gusev Crater and for Oppy, the potential landing places were : Isidis Plantia, Melas Chasma, and Hematite. I don't know when the JPL made the final selection of places for MER. It might be done during any of the 6 TCM.s

Rodolfo

Interesting to note that they actually considered a Polar landing site for Viking 2. In one sense its a pity that like either Hellas or Argyle they did not chose to go ahead with a landing because the science & scenic results could have proved a useful contrast with Viking 1.

Viking had to land at a lower elevation than Meridiani, and it had a huge landing ellipse size, way bigger than Gusev crater.

Viking sites were chosen on Mariner 9 images and those sites certified by Viking. Meridiani looked like a big nothing to Mariner 9.

The NASA SP referred to above is a good guide to the process, though it has annoying gaps which I hope to fill.

Fill - I mean Phil

At the time, they thought the Viking-2 site at Utopia was smooth. And, at the 100 meter resolution of Mariner-9 images, it is one of the smoother areas on Mars. The fact that boulders were everywhere was missed. In fact, looking at the distribution of large boulders at the Viking-2 site, it seems that it was the really lucky Viking. While Big Joe was definitely a threat to Viking-1, there were definitely more areas that were not so threatening around Viking 1. The Pathfinder site was also chosen from really low resolution data (in this case, images from Viking that were, if I am not mistaken, nearly kilometer scale). Hopefully it will stand as the last site chosen this way.

Someone somewhere ( MM perhaps ) has commented that terrain that looks smooth in VIking imagery is typically rough at the MOC resolution - and vice versa.

Doug

Nope, the sites were selected a little less than 2 months prior to launching MER-A. Click here:

Planetary Radio - Return to Mars: Two Rover Landing Sites Chosen - Airdate: Monday, April 21, 2003

I've been wondering how many sites are already being recycled in each site selection process. Are those proposed for MSL also the ones that were not accepted for the MERs? Or is there any site formerly considered for the Vikings (to bring it back to Vikings in this Viking thread).

Several of the MSL proposed sites are not far from Opportunity.

The four serious MER sites were Gusev, Meridiani, Elysium and Isidis.

http://marsoweb.nas.nasa.gov/landingsites/index.html

Of the MSL sites - 5 are proposed to be in the Meridiani district, and while Gusev's not there, the remaining two MER sites are.

Doug

To be fair, Viking 2 was different geologically, and also in terms of climate, although the appearance was certainly similar. I have been working on the best of the Viking-2 frost-scapes. There is a super resolution view from the low-resolution RGB data for this set. There is a similar highr resolution image area, but it is noisy, the frost doesn't match, and the angle is slightly different.

Beautiful, Ted...now my wallpaper, thanks!

Just had an odd thought: We truly don't know what's directly underneath either of the VLs....what do you suppose the odds are that rocks that came that close to wrecking one or both of the spacecraft are sitting under there just a millimeter or a bit more away from a vital area? Brrr....

Thanks!

Well, we do know that Viking 2 had a footpad on a rock, which gave its images their trademark tilt.

And Viking Lander 1 ended with the "left front" footpad entirely buried in a dust drift.

The thing we *REALLY* don't understand for sure about the VL2 site is the boulder population. Is it, as has been speculated, due to an ejecta-flow-lobe from the large 100'ish km or bigger crater, Mie, to the east? Is is ejecta, but not a flow, as discrete lobes are not visible on the orbital images of the immediate landing site vicinity?... or what?... if the Utopia plains are mantled terrain with ice/permafrost features... is the boulder population of obviouly basalt-lava-type rocks entirely superimposed on tens of meters of more or less icy or dessicated dust? (we see faint polygonal trough features in the lander's vicinity).

The site just doesn't quite make sense and never wholly has.

karolp - there's no recycling of sites in the way you are suggesting. Diffeent missions have different goals, and different engineering constraints, and different landing ellipse sizes, so every one starts off fresh with new suggestions. Of course there is some repetition, but people don't just brush off the Viking list or the MER list, they start fresh. And a big part of that is having better data each time.

Phil Stooke

"Ken Edgett was able to offer the people attending [a June 1999 site selection workshop for the 2001 Mars Lander, later canceled] general rules that he and Malin had come up with for guessing what a MOC image might contain on the basis of Viking pictures of the same site. The best of these was that sites that looked smooth in Viking pictures looked rough when seen through the eyes of MOC and vice versa." Oliver Morton, Mapping Mars, at p. 230.

I believe that a similar rule of thumb applied to comparing Mariner 9 pictures to Viking orbiter pictures. See Mapping Mars at 226-27.

TTT

Here is another frost image - I have always liked this scene - there is another frost image image that is similar, but without nearily as much frost. This set is badly overexposed on all channels, although blue is somewhat better. The 6-bit nature of Viking transmissions didn't like frost.

I remember it fondly from an old (1978?) issue of Science or Sky & Telescope, Ted...striking...how strange yet familiar, eh?

BTW, was the final verdict for the VL2 frost a 6:1 CO2/H2O clathrate after all? Never heard anyone state that it was pure water.

Ted, you made my day. That frost picture has always been one of my favorites, but I've never been able to find a large clear version of it.

The raw data is really bad, especially on the far left. In fact, I did most of the color through color cloning in the leftmost 50 pixels, because the salt and pepper on the raw images was wrecking havoc, even after being removed (there was so much of it, especially in the red image, that pixel values were hard to reconstruct). I have seen attempts to reconstruct this image using high resolution views of this scene with frost on it. However, the illumination and frost patterns don't match, making it look artificial.

I was reading through a copy of Olivier DeGoursac's 'Visions of Mars' and on page 39 discovered that the Smithsonian has already made a plaque to be put on Viking One when a human finally reaches Mars.

Does anyone know what the text/image(if any) is on the plaque?

That aside the book is an interesting read, though I do disagree with his statement that rovers are automatically superior to fixed location landers for the purpose of Martian exploration. Of even more interest our own Phil Stooke is one of the people thanked at the end of the book for the information he supplied about the probable location of Viking Two.

Fixed landers can be just as scientifically able...but they cannot conduct exploration

Olivier is an UMSF regular

Doug

On MER we "downselected" (from I think 6 or so) to 3 sites in the months leading up to the 4th MER landing site review in Mar 26-27, 2003. These were Isidis, Elysium Planitia (where we had two ellipses to chose from), Gusev and Meridiani. The latter two being the favorites with the scientists. Unfortunately both Meridiani AND Gusev looked too risky for MER. In the case of Meridiani, it looked pretty safe to us from orbit (flat as a pancake) but being about 1.4 km below the MOLA-defined "sea level, the EDL timeline was looking too short for the comfort of the review board (all the other sites were lower still and hence had more timeline margin). In the case of Gusev, much of it was both rocky, somewhat windy and not that flat and the "worst case winds" simulation results I presented to the board were, well, rather ugly. (In one case I showed a 30-40% probablity of landing outside the airbag "capability envelope" (the impact speeds and directions we felt were safe to land in).

After a lot of talking (not heated but intense) and quick overnight EDL simulations, the board bought off on Meridiani as safe for one of the rovers. But Gusev (the one that looks like it could have once been a lake), was nixed! Instead Isidis or Elysium were "chosen" as the safest places to target. These were not deemed interestings site by most of the scientists. But they were the safest and flatest. This was not good. We offered an alternate strategy, we would do better simulation and even more airbag testing (grazing impact angles) to try to show that Gusev was safe. If not, we would fly to Isidis. We would launch MER-A (first launch) targeted toward Isidis and if the post-launch testing in the summer of '03 showed Gusev to be save afterall, we would do a TCM (course correction) in Aug/Sep to go to Gusev OR Meridiani OR Elysium. The second launch, MER-B, would be targeted at the outset for Meridiani. (We might have landed both rovers in Meridiani!!)

Not only did we do airbag drop tests after launch, we also did parachute inflation tests and RAD / TIRS rocket test that summer of '03! (Lots of people did not understand that we could learn about the system we built and use the extra design capability to justify landing in places that initially did not look safe.) All to be able to prove that it was safe to go to Gusev and Meridiani. We had a review in late summer and presented the test results to the board and they bought off Gusev and Meridani. So the final final site selection for Spirit occurred after launch!

To answer your other question, yes the old (and current) MER sites that the MER team assessed in 01-02 are on the "plate" for possible landing sites for MSL. They have a lot more besides. MSL's EDL design (guided entry plus skycrane) allows a lot of safe landing site possibilities than we had for MER. The landing ellipse is a lot smaller, it is unaffected by winds, and the rover can touch down on steep slopes and has the rock clearances for landing on very rocky surfaces (large rocks). (Can you tell that I am partial to it??)

I have no idea which will win, but I am personally in favor of Mela Chasma in Valles Marineris. The view from the valley floor would be amazing. Walls as high as the tallest mountains on Earth! (Obviously an enginer talking.)

-Rob


***********
All comments made here are that of the author and do not represent the views of NASA, Caltech nor the Jet Propulsion Laboratory.

Didn't the ESA Mars Express probe detect what they think is water ice under Elysium?

Wouldn't that make it a target of interest now?

True, but there is something to be said for long term observations of a location. A classic example is Mawsons expedition to Antarctica, the location he chose for his main base is commonly known as the 'home of the blizzard' however when he arrived the winds were calm, had he simply made a short say and left to set up somewhere else then it is possible that this locations unique climate would not have been discovered or studied .

In any case fixed landers can compliment mobile rovers by providing 'ground truth' about a particular location. One thing I'm surprised that NASA has not considered at some point is dropping a rover in the vicinity of the Viking sites and sending it to get images of the landers, that is, once the lander positions have been verified in some fashion.

Idea is good but there's so many places to explore! We had a comon feeling up to the 4th landing (V1,V2, Pathfinder and Spirit) that all Mars was alike and then came Opportunity showing us a totaly different looking place. Now, I understand that Meridiani is one of a possible target for MSL (they even consider different places in Meridiani) but well, will it not be better to explore a totaly different location? Like what Phoenix will do? So, I believe that going back to known places doesn't bring as many science as exploring new territories, at least as long as we are in the Exploration phase.
The good thing with rovers is that when they'll loose their mobility, or when they can't exit a crater, they become landers

I quite agree - a long duration net lander mission for met.obs and hopefully seismic study would be a very very valuable feather in the mars exploration cap.

Doug

Specialy if we can send a network of "cheap" dedicated such landers

We did, it was called Pathfinder, they just didn't make any more. In my personal opinion NASA should have launched a 'fleet' of Pathfinder replicas to Mars in 98/99 rather than what they did send.

Then again I think they should be sending Pathfinder replicas to Mars with Pheonix in '07, a 'high/low' approach would provide a great way to get simultaneous surface measurements over a wide area, especially if the rovers are still operation by that time. (For a little more information the 'high/low' idea check out post 232 in this thread

Of course, the whole purpose of Pathfinder was to test the technology for a whole series of landers like it, which would have provided a network of stations across the planet. It was originally called MESUR/Pathfinder (MESUR - Mars Environmental Survey). The mission was killed in development due to lack of funds, but the Pathfinder for that mission (which we now know as Mars Pathfinder), was given a microrover and sent out as a posterchild for Faster Better Cheaper, probably because it was far enough along in development that it could be sent off quickly. So it ended up being set to pathfind for a mission that was never to be....

It's little rover was kind of cool though...

I knew about MESUR but heard that aside from the airbag landing system, NASA was planning something completely different from the Pathfinder Lander, for one thing it was going to use an RTG powersource like Viking.



I always thought it looked kind of cute

Indeed, Mars Pathfinder (MPF) was originally intended to be the first low cost lander for an eventual Network lander design. However we discovered that we could not build an lander that could deliver 20 something kg of science payload to the surface (including Sojourner) unless the whole vehicle (entry) mass was around 500 kg and that does not inlcude the mass of the cruise stage. (Yes a 4% mass fraction does sound a bit low but that's how it goes. I do not know how to make it lighter without making the system much more risky or much more expensive.) So the idea of sending a bunch of landers only makes sense if you can afford to have many small launch vehicles (like the Delta II) or one very large vehicle to get them headed to Mars from Earth. Plus, despite being relatively cheap, most net lander architectures need to deliver 3 to 6 landers to widely separated spots on Mars (for weather and seismic studies). You also have to ask yourself what science you can do for 20 kg of payload. (And that 20 kg has to include the mass of the hardware that puts it on the surface - like rover ramps, the rover, or an arm or a drill, or a mast, plus the sensors themselves.)

When these factors were weighed several years ago, the preference instead was to work toward an eventual sample return mission and net landers were set aside. MSR meant that things had to get bigger and that the payload had to do more.

MPF did some good science, but many felt that it came up short of what a mobile surface mission COULD do. (I do not feel much embarrasment however, afterall it WAS the first new mission to Mars since the Viking missions AND the first Mars rover - it was a huge challenge that we are still proud of and it has changed the course of Mars exploration history.)

Ironically while MPF turned out not to be a Pathfinder for network landers (at least not yet), it WAS a pathfinder for MER and even MSL. In fact we all agree that there is no way that we could have pulled off MER without the MPF design behind us (even if we had to redesign nearly everything).

-Rob

***********
All comments made here are that of the author and do not represent the views of NASA, Caltech nor the Jet Propulsion Laboratory.

Pathfinder certainly is not an embarassment. My point is that, while I will grant that the MESUR design wouldn't have worked unless we had a much large budget, that the only other network idea that has ever been extensively studied in the time since is Netlander, which also died on the vine. Pathfinder, in addition to showing us a new place on Mars, returned very interesting results, including Sojourner's discovery of an overabundance of oxygen in the rocks, indicating the presence of water at one time. The final results were published in late 2003, which caused them to be quickly overshadowed by the MER results. Given its funding level, the lack of an orbiter to return data, forcing it to rely on a very limited data return rate, and a crappy battery as far as planetary missions go, it was an extremely successful mission.

One current project of mine (my goal is to finish by Pathfinder's 10 year landing anniversary by assembing as much as I can of the superpan, combined with gapfil from as many pointings as I can find from non-covered areas.

Remember that Pathfinder was an engineering test mission, not a science mission. As with Clementine, Deep Space 1, Smart 1, and to a lesser extent Hayabusa, ANY SCIENCE RETURN IS GRAVY.

Pathfinder proved we could get down onto Mars for less than 1/10th the cost of a Viking mission in terms of then-current dollars. Maybe 1/20'th.

Granted, airbag landers are better smaller than Pathfinder, not bigger, as MER proved (though successful in the end, it was nearly DESPITE the airbag system!); but Pathfinder got us going back DOWN onto Mars, not just going in circles around it.

Speaking as someone for whom Vikings Mars was the only one I knew, I can only re-iterate what has just been posted. Pathfinder was not an embarrasment, it was a wonderful achievement, reading your post above I now have a better idea of just why there was no 'true' follow-on to Pathfinder.

I still think however that 'basic' landers like Pathfinder have a useful role to play in Martian exploration, complementing the work of more sophisticated probes.

(Spelling mistake corrected.)

Only if you can program those 'basic' landers to send messages to the more sophisticated probes that say things like "Hey, you're doing a great job! And you look great, too!"



(FYI, the word that means 'adding to another's capabilities' is spelled 'complement.' A compliment is a remark designed to praise someone or something... )

-the other Doug

Thanks for catching my mistake there, but I don't think that it eliminates the point I was trying to make, the current strategy for fixed landers at least, relies on single probes.

Landing a single 'high complexity' fixed lander and at least one other 'low complexity' fixed lander designed to cover the basic (weather/imaging) measurements provides the opportunity as during the 1976-1980 period of the Viking mission for gathering near-simultaneous readings of conditions from different regions of the surface. This allows the determination of how regional differences effect the general Martian weather pattern discovered by the two Viking landers.

Historical example, during the 19thC someone went around the world looking at clouds to ensure that they all looked the same no matter where in the world they occurred. As it turns out clouds seem look much the same no matter where you are in the solar system (Where actually they form that is...).

Very true. Had Spirit and Oppy had weather stations, it would be hard to study long term things like windspeed when at times it was on the plains, on a hill, and in the inner basin, to name a few places. I think the thread on changes seen by Spirit at Low Ridge Haven, where it is functioning as a lander as of late, really points to the value of stations. I thought it would be cool to have a rover that drops off little weather stations. Imagine if Oppy left one in Endurance and one on the rim. That would be some interesting data.

Mars Pathfinder had a little windsock that resembled an old TV antenna with small
cones attached to the rods. Why didn't they put one of those on MER? I don't think
it would have used up any rover power?

Well - firstly you've got to find the space for the thing - MER was the most tightly packed 'dense' thing. Then - you've got to spend Whrs and Mbits imaging the thing and send those images back. Then you've got the thing stuck up in the way for imaging like a stretched LGA, wobbling around casting shadows on the solar arrays.

There are smaller, lighter, better ways of measuring wind speed and direction (like Beagle 2's little instrument) that might have got smuggled on board - but meteorologists don't carry rock hammers, and Geologists don't carry anenometers seriously - to learn something from the wind I would have thought you would want to have a static station

Doug

I know the MERs were right on the edge of the mass limits... but, it seems to me, if there had been enough margin to do it, you could have placed a small weather station and a small, local transmitter on the lander base units. Have them communicate with the MERs via a low-power UHF signal, which would use the existing UHF equipment that the rovers use to communicate with Odyssey. It wouldn't have entailed a single extra gram of weight on the rovers themselves, only the weight of the weather sensors, transmitter and batteries (and/or solar cells) to power the rig on the lander base units.

I can imagine doing the whole thing in less than 10 kilos, deployment apparatus included. Would 10 kilos have blown the landers' mass budget?

-the other Doug

I think this one's been done to death in the past.You'd have to have arrays ( which would get driven over ), power management, a 'cpu' box, the instrumentation, the transponder, the antenna, all in a lander deisgn which is over mass budget and packed tight already. Even if it was physically possilble to put in in there ( which I doubt ) without going over budget ( which I doubt ) - given the chronological and financial constraints on the mission that were already beyond a joke - I don't think they'd have had the time or cash to do it.....and at some point someone's going to say "OK - you can have 10kg on the lander...what are you going to take off..." and the first thing would be the entire rover science payload

Doug

Another problem with the idea of having weather stations on the MER rovers...

They spend a very large fraction of the time asleep or even in deep sleep. The Mossbauer and the X-ray alpha instruments can both <i think> be powered and integrating data on their own when everything else is in sleep mode, but those are major exceptions.

I really would like to have had Met data on the rovers, but the question you must ask 100% of the time is what would have you left off to include what you're wishing for?

Beyond mass limitations, one must also remember time - they nearly ran out of time building the things, so placing a small station on the lander or on the rover deck, in addition to being a mass issue, would have been an issue here. They were racing against the clock for a 2003 launch. The window was a particularly good one, and later windows, such as 2005 and 2007, would have required a larger rocket.

10 kilos!?!? :-o

In fact Squyres's first integrated payload proposal included a meteorology package "in hopes of making our payload attractive to any atmospheric scientists who might review it." Roving Mars at 23. The Met package dropped out in late 1995 when the team started exploring putting the payload on a rover. RM at 31.

Numerous iterations later, when Goldin signed off on the MER project and the engineering began in earnest, MER's mass budget was in fact quickly busted and stayed busted. RM at 108-113. A sun pointing camera was thrown off "to save a lousy three hundred grams." RM at 128. For a while the long knives were out for the RAT and the Microscopic imager, which together totalled about a kilo, and they considered eliminating one of the two antennas, as well as the solar array's fold-out winglets.

Ultimately they couldn't fix the mass budget. Although the original proposal had been premised on reusing the Pathfinder lander, airbags, and parachute, the project resigned itself to redesigning these systems, huge budget-breaking tasks to add to a schedule that was already impossibly tight. They didn't have a working parachute until 7 months before Spirit launched. RM at 141.

Although Roving Mars suggests that Spirit was cleared to attempt the windy plains of Gusev Crater after they finally ran a successful parachute test on October 30, 2002, RM at 141, a fascinating recent post in this thread by Rob Manning reveals that further testing and analysis were needed after launch, including airbag drops, parachute inflation tests and RAD / TIRS (steering rocket) tests, before the project accepted the risk of landing their spacecraft at Gusev.

Your ten kilo weather station had about as much chance of approval as a steam calliope. :->

TTT

How much would it have cost in both economic and weight terms to have
a few simple weather sensors on the MER landing platforms?

I am not even talking a minicam here, just a few chips to measure temperature,
pressure, and maybe wind velocity.

Would rather have had that than those two Lego "astronauts".

The landers were dead once the rovers rolled off. So you'd also need a power source, a telecom system, etc.

[after the fact...i noticed that some of this thread is aimed at the landing platform...so my babbling below is a little off-topic].

it is non-trivial to do a good job with an experiement designed to make such set of measurements. the rover has many temperature sensors for engineering purposes. the trick is to obtain "temperature" and "wind velocity" in such a way as to minimize the perturbations due to the rover itself. wind is particularly problematic (it has taken a lot of re-analysis to get the Pathfinder data into a cohesive set of information...work by Jim Murhpy at NMSU). it's the lack of a useful pressure sensor that really annoys me...since one desires this value as a boundary condition on Mini-TES atmospheric temperature retrievals (looking upward).

as for temperature, you just can't put a temperature sensor on the rover surface without running into problems (which is why Viking and Pathfinder used a "mast" system...perhaps one on top (a foot or so) of the camera bar. fortunately, with Mini-TES spectra, one can derive surface temperature and ~1-meter height air temperature (averaged along the path to the targeted surface element). The 1-m air temperature is not particularly sensitive to the pressure boundary condition compared to the upward-viewing retrievals.