MSL landing sites Options

[Drkskywxlt]

I wouldn't be too surprised if martian dust has abrasive properties.

So much of the pitting we see on rocks lying on the surface are inferred to be due to abrasion by airborne dust over long periods of time, no? So it surely is abrasive. I wouldn't think it would be quite as abrasive as lunar dust (with the very high surface area to mass ratio) given that martian dust gets lifted into the air and knocked around quite a bit more than lunar dust, which should smooth it down somewhat.

[Guest_Oersted_*]

Edited to add some facts to my speculation
Apparently the EDL data from the six successful landers is critical because it provides higher resolution data than any other mechanisms for critical parts of the modelling problem so I'm wrong there - see this for some more detail.
End Edit.

Big credit to you for this display of a self-effacing, scientific attitude. Data rocks and so do you!

[Guest_Oersted_*]

I much prefer Eberswalde, just avoid the built-up area:

http://www.google.be/maps?ll=52.833106,13....m.panoramio.all



Jokes aside: a river delta fed by MEANDERING rivers! - What is there not to like?

http://marsoweb.nas.nasa.gov/landingsites/...rswalde_opt.pdf

- Great read.

[KrisK]

So we've got the Fifth MSL Landing Site Workshop (May 16 - May 18, 2011)
http://marsoweb.nas.nasa.gov/landingsites/index.html

Here is a nice quick characteristics of the landing sites (pros, cons, unknowns)
http://marsoweb.nas.nasa.gov/landingsites/...th_Workshop.ppt

[KrisK]

Fifth MSL Landing Site Workshop presentations
http://marsoweb.nas.nasa.gov/landingsites/...op/program.html

Can't wait to see MSL on Mars...

[sgendreau]

Fifth MSL Landing Site Workshop presentations

I'm sitting in the audience at the workshop, watching the final discussion on site pros and cons. Very smart people in ferocious debate. Most of the audience is fiercely in one of the four camps. Matt Golombek and John Grant are trying (some but limited success) to extract consensus on each site's points. Since I have no horse in the race, watching the race is fascinating.

EDL is very very sure of themselves at all four sites. Science-wise, no site seems to have an edge. Anyone have a specific interest or question? No promises but I'll try.

[dmg]

The workshop is available for viewing/listening via a Webex feed (https://jpl.webex.com) and anyone can sign up to see/hear. I've been listening and watching out of the corner of my ears/eyes for the last couple of days and it is fascinating to watch the process take place. For each site they are fighting over a "quad chart" that delineates the Overarching Hypothesis; the Possible Pros; Possible Cons; and Remaining Uncertainties. These have been developed over the prior MSL Landing Site Workshops and are being modified as they speak. There were a couple of days of presentations and now an open discussion, site by site, of the Pros, Cons, and Uncertainties. Very interesting (even though most of it is a bit above my head -- I get the gist of the discussion).

[centsworth_II]

...Science-wise, no site seems to have an edge....

What stirs my imagination is this from the Mawrth Vallis quad chart: "Exposes the oldest preserved layered stratigraphic section of the four candidate sites... may be among the oldest preserved on Mars and may be from a period not recorded in the rock record on Earth." Just as Studying Titan may give insight to early Earth atmosphere, studying Mawrth may give the best insight to early Earth geology -- and definitely give the best insight to early Mars geology. I like the idea of studying layers formed at the time when early life may have been getting its start on Mars. We don't have this opportunity on Earth.

I also agree with this: "Steve Ruff making a forceful point if all 4 sites OK, why pick 1 of 3 Go-To sites rather than Mawrth where landing site has science?" And don't agree with Jim Bell Response as reported on Twitter (below). The keys are not being thrown away. They are being used to go yet further after landing site science is done. To me, if the quality at all four sites is equal, then the site where substantial science can be started sooner has the advantage of quantity in addition to quality.

[elakdawalla]

It's not that simple, though. Paolo showed a chart today that made it clear that of the four sites, Mawrth makes for the slowest and most challenging driving. (Eberswalde is also on the difficult side, compared to Gale and Holden.) Why would we go to a place where we had to fight our way across ripples and around undriveable slopes if we could go to a place with clear driving between science sites, where blind driving plus autonav can take us far, far away from our landing site into a new geologic context? Field geology is all about traverses -- going as far as you can, sampling along the way, to see how things change, look for geologic contacts, and always keep moving.

I'm not actually saying I prefer other sites over Mawrth. People keep asking me which one I prefer, and I just don't have a favorite, because to have a favorite I would need to understand all the arguments better, and I just haven't been paying good enough attention. The one I am most concerned about is Eberswalde, because there is a distinct possibility that that incredible delta system all formed in a very short period of time, so I think it would be less valuable than the longer geologic histories represented at the other sites.

[nprev]

I think Emily has an excellent point. One thing to remember is that MSL is likely to be quite long-lived, even by MER standards (yeah, that was a shout-out! ) Inherently sudden/catastrophic events are interesting in their own right, but they have more of a gee-whiz factor than a root science potential.

Maybe the debate should refocus on the science objectives in this context. My understanding, though it might be wrong, is that one of MSL's core goals is to ascertain not only whether Mars once possessed a habitable environment but also (crucial point) how long it may have persisted. Eberswalde does not seem to offer as much potential to address that question as some of the others.

[elakdawalla]

John Grant and Matt Golombek kept coming back to the tired metaphor of apples and oranges. Mawrth is apples; the other three are oranges. In the room there are people who prefer one or the other, have spent their careers studying one or the other, and really, no amount of argument is going to change their minds. Changing their minds wasn't really the point, which is why no vote was taken. The minds that matter are the ones who were sitting in the front row -- John and Matt, John Grotzinger, the engineers, the HQ folks. They will make the decision between apples and oranges.

[PDP8E]

MSL Landing Site team:

Holden seems like Gusev... to this armchair martian explorer, do we really want to look at another volcanic littered and billion year wind-swept and dust covered crater? Is there a Home Plate fumarole there to study... or mud volcanoes?

The delta of Eberswalde may not be easy to maneuver around; and its a negative delta, the braids, are now raised very high.

Mawrth... what a place. An extensive valley with everything at your landing spot.

And then the 150 mile Gale Crater. It has a Pike's Peak sized mountain in the middle. The experts don't know what it is or how it got there. Within the crater is a crazy deep and layered valley that we can cozy up to and study (albeit, from afar). The traverse up Pike should reveal many surprises.

What is the purpose of MSL? looking for water? looking for geographic layers? looking for life? or just maybe exploring the unknown and unknowable? If we lived on Mars and tried to pick a landing spot on Earth a half a million years ago, would we choose the Sahara or the Grand Canyon?

Pick one.

Explore, seek, and learn. The landing attempt via the sky crane is very bold engineering. Landing Site Pickers: be bold.

Pick one.

With the history of exploration as our guide, this is a just the beginning of exploration. You really can't pick wrong.

Pick one.

< i now step off my soapbox ... thank you >

[jasedm]

If we lived on Mars and tried to pick a landing spot on Earth a half a million years ago, would we choose the Sahara or the Grand Canyon?

Neat analogy.

If that were the case though, we'd probably be designing a craft along the lines of WISE, and be aiming to drop it into the Pacific....

[Eluchil]

They are all excellent sites. I must say, though, that unlike MER where I become a convert to Gusev after reading a presentation about how the Athena science payload could be used to directly test hypotheses there, I already had my mind basically made up. When I first saw the meanders of Eberswalde (back when it had no name and was called Holden NE for reference) I knew that was where I wanted a lander to go.

In reality, there are real concerns about the site and one of the others may be just as good or better, but emotionally it would be a literal dream come true to have a lander at Eberswalde.

More generally, I think that morphology provides more concrete hypotheses to test than mineralogy does. And a clear result, even a negative result like that ultimately derived at Gusev, is very valuable.

[elakdawalla]

This decision is the battle of mineralogists vs. geomorphologists all over again, and we know who "won" the fight, at least initially, on MER: Meridiani (the mineralogists' choice) provided almost instantly the results that the mission was searching for, while Spirit wound up in the infamous "basalt prison," not finding evidence for past water until Pot o'gold. So it would seem obvious to pick Mawrth. But there is a HUUUUGE difference this time around: MRO. Between HiRISE and CRISM the amount we know about what's there to see at outcrop scale has increased by orders of magnitude. Remember it's CRISM data that's drawing Opportunity all the way to Endeavour. CRISM certainly points to Mawrth as a very interesting spot. But HiRISE has equivocal stuff to say about Mawrth. And if you can't understand the local geologic context, no matter what you learn at the landing site you won't be able to understand its implications for other places on Mars, which would represent a failure of at least one mission goal (though if Curiosity sees dinosaur bones at Mawrth, no one will care about that particular failure).

Another point is that the mission people, Grotzinger especially, keeps hammering on, is this preservation issue. We'd like to know if there were organics present at a time where there was water and energy, because these are the ingredients for life (we think). But organics get destroyed so easily by water. Mawrth is so ancient, and appears to have had so much water (relative to other places) that you have to question whether any organics that may have been present would have been preserved. I wasn't there, but I suspect that it was concerns like this that led Bibring to comment "I am amazed that now we are saying there's too much water on Mars!" (a quote reported via Twitter). I was talking with Jeff Kargel afterward and he said that his impression was that the best hope for preservation would be in stacks of rocks that contained both phyllosilicates and evaporitic stuff, implying occasional total drying out of the landscape. Mawrth does have the evaporitic stuff in the form of sulfates. So does Gale. Mawrth has higher abundance of these interesting minerals (though it's really incredibly difficult to get abundances out of spectra, so that statement could be false). Gale has a thicker section.

Back and forth. If forced to bet, I'd hedge by laying money on both Mawrth and Gale. I'm told it's entirely possible that the mission will narrow the choices down to two and punt to HQ for the final decision. But I hope they don't -- that seems like a kind of cowardly way out.