Watery past of Libya Montes Options

[SigurRosFan]

- http://www.esa.int/SPECIALS/Mars_Express/SEMWGVM65LE_0.html

--- The HRSC obtained these images during orbit 922 (7 October 2004) with a ground resolution of approximately 14.3 metres per pixel

On the basis of crater-size frequency distributions on the valley floor and surrounding terrain it has been shown that the formation time of the valley amounts to approximately 350 million years.

Determinations of discharge (valley) volumes on the basis of high-resolution HRSC derived digital terrain models reveal discharge rates that are comparable to those of the middle reaches of the Mississippi river in the USA. ---

Summary: Between 3.5 billion and 3.15 billion years ago --> a "Mississippi-like" river carved a 400 kilometer long valley

[TheChemist]

The valley is 3500 million years old, there is a typo on the ESA page.
Europeans ...

[dvandorn]

No, I don't think it was a typo. I think they mean to say that the valley formed roughly 3.15 to 3.5 billion years ago, and that the active valley-forming processes acted over the course of 350 million years (which happens to be the interval between the beginning and ending dates of their overall estimate).

I can definitely understand how counting *differential* cratering abundances can give you the number of years it would take for a given landform to have developed. If our assumptions on the impact flux are correct, then the oldest portions of this valley have the right number of craters to be about 3.5 billion years old, while the most recently emplaced portions of the valley have the right number of craters to be about 3.15 billion years old. So, you can state that it took 350 million years for the valley to form.

At least, that's how I interpreted the article.

-the other Doug

[Guest_BruceMoomaw_*]

This is also one region where the OMEGA instrument has seen fairly high local concentrations of phyllosilicates, indicating large amounts of neutral Noachian liquid water.

Ironically, this region was the landing site originally assigned to the cancelled 2001 Mars Surveyor Lander, before it was moved to Meridiani and then cancelled. Who knows? If it HAD landed there, it might have discovered something even more interesting than what we've found at Meridiani...

[TheChemist]

No, I don't think it was a typo. I think they mean to say that the valley formed roughly 3.15 to 3.5 billion years ago, and that the active valley-forming processes acted over the course of 350 million years (which happens to be the interval between the beginning and ending dates of their overall estimate).
-the other Doug

You are absolutely right, and I am a complete fool

PS. To Doug : (the other other one)
I desperately need a smilie for <<inserting foot in mouth >>

[Guest_AlexBlackwell_*]

Ironically, this region was the landing site originally assigned to the cancelled 2001 Mars Surveyor Lander, before it was moved to Meridiani and then cancelled. Who knows? If it HAD landed there, it might have discovered something even more interesting than what we've found at Meridiani...

If I remember correctly, the highland landing ellipses made the 2001 Mars Surveyor Lander folks nervous, and subsequent candidate landing ellipses were moved down on to Isidis Planitia (closer to the crappy Beagle 2 landing site) to sample the depositional "outwash" from the highlands. Given its lack of mobility, though, I think Squyres's post-MER "nightmares" about APEX at Meridiani would have applied to Libya Montes as well.

[Guest_AlexBlackwell_*]

If I remember correctly, the highland landing ellipses made the 2001 Mars Surveyor Lander folks nervous, and subsequent candidate landing ellipses were moved down on to Isidis Planitia (closer to the crappy Beagle 2 landing site) to sample the depositional "outwash" from the highlands. Given its lack of mobility, though, I think Squyres's post-MER "nightmares" about APEX at Meridiani would have applied to Libya Montes as well.

After a bit of research, I discovered my statement above was in error. The 2001 Mars Surveyor Landing Site Workshop downselected two sites: Isidis Rim and Hematite Region (Meridiani Planum). The Isidis Rim ellipse did indeed encompass the Libya Montes site as Bruce noted.

The ellipses I was referring to above "down on...Isidis Planitia" were for the 2003 MER landing site selection process when the 2001 MS landing site in the highlands was judged too risky for MER. For example, see Larry Crumpler's 32.5 Mb PowerPoint presentation from the October 2001 MER Landing Site Selection Workshop in Pasadena or this 2.2 Mb JPEG image.

[Guest_BruceMoomaw_*]

Yeah, I did a whole SpaceDaily article on that selection. What made the Libya Montes plausible as a landing site for MS 2001 was its new precision-accuracy landing software, which would have enabled it to land in one of the valleys between the very rugged mountain ranges of that region. MER, of course, didn't have that (and I've now heard one fuzzy report that they've removed it from Phoenix as a cost-cutting measure -- which I need to confirm).

[David]

Yeah, I did a whole SpaceDaily article on that selection. What made the Libya Montes plausible as a landing site for MS 2001 was its new precision-accuracy landing software, which would have enabled it to land in one of the valleys between the very rugged mountain ranges of that region. MER, of course, didn't have that (and I've now heard one fuzzy report that they've removed it from Phoenix as a cost-cutting measure -- which I need to confirm).

Why would you remove software? I mean, it doesn't weigh anything, does it? And even if it takes up computing space, it obviously wouldn't be needed after landing and could be swapped out for something else.

Obviously I'm not understanding some key point here.

[djellison]

But it does take time and money to write, test, re test etc etc.

Doug

[Guest_AlexBlackwell_*]

Yeah, I did a whole SpaceDaily article on that selection. What made the Libya Montes plausible as a landing site for MS 2001 was its new precision-accuracy landing software, which would have enabled it to land in one of the valleys between the very rugged mountain ranges of that region.

I thought the precision landing capability for 2001 MS Lander was dropped fairly early in the design process, even before landing site downselect. In fact, although originally envisioned to be distinct, I believe the 2001 MS Lander bus turned out to be a virtual duplicate of the MPL bus.

[Bob Shaw]

I thought the precision landing capability for 2001 MS Lander was dropped fairly early in the design process, even before landing site downselect. In fact, although originally envisioned to be distinct, I believe the 2001 MS Lander bus turned out to be a virtual duplicate of the MPL bus.

Different solar panel design for some reason...

Bob Shaw

[Guest_AlexBlackwell_*]

Different solar panel design for some reason...

Yes, 2001 MS Lander was to test a new set of thin-filmed, flexible solar arrays in conjunction with the DART experiment.

[Guest_BruceMoomaw_*]

(1) I've heard what seems to be a fuzzy reference from the Phoenix team themselves to dropping the precision landing software in order to cut cost and programming complexity -- as well as because it's not really needed for the kind of terrain Phoenix will be landing in. I need to confirm this, though.

(2) I can vouch for the fact that they had NOT dropped it from MS 2001 at the time the mission was cancelled.

(3) There were a really astounding number of other differences -- genuine hardware differences -- between Mars Polar Lander and the MS 2001 Lander, which were lovingly listed by that gent (can't remember his name just now) who had a lengthy website up for a long time urging reuse of the MS 2001 Lander, as part of his evidence that it might not share MPL's failings. He's no longer on the Web, but I have copies of most of his stuff -- including that list of differences. Just give me time to find it on my CD-ROMs.

[Guest_BruceMoomaw_*]

After a very thorough (and annoying) Web search, I still can't find solid confirmation that they've stripped Phoenix of its guided-entry software -- but there is no mention of it on the official website, and the landing sites are being planned on the assumption of a 75 x 150 km ballistic landing ellipse. (The latter however, might be just a safety precaution in the event that a guided entry got cancelled at the last minute.) I have been able to reconfirm that it was in the official plan as late as 2004, but then I already knew that.

In the process, I did manage to dig up a Feb. 2005 piece -- http://clusterlaunch.esa.int/science-e/www...fobjectid=36770 ; I have no idea why it's in the ESA's website on the Cluster mission! -- which notes that, while Phoenix can detect "complex organics", it "will have little chance of distinguishing biotic and abiotic organics." (Boo hiss, but I think we already really knew that.) Also, the official Phoenix site now features weblogs by team members ( http://phoenix.lpl.arizona.edu/features/weblogs/ ) -- and Deborah Bass says in hers that a new feature has been added to the back of the sample scoop: a rotating shredder to detach bits of permafrost for the scoop to pick up, since it isn't strong enough to bite into it directly.

As for that stored document of mine on the differences between the 1998 and 2001 landers: give me a bit more time to look for that.