spacEurope counted once more with the precious participation of our Researcher X at the third landing site selection meeting for the Mars Science Laboratory (MSL), taking place at Monrovia, CA.
Here are his impressions on the meeting's first day:
I'm in attendance at the 3rd MSL landing site workshop in a Doubletree Hotel in Monrovia, CA. The goal of this meeting is to further help focuswhere this remarkable vehicle will attempt to explore. The good news isthat we are down to only seven sites {Eberswalde Crater, Holden Crater,Nili Trough, Mawrth Vallis, Miyamoto Crater, S. Meridiani, and GaleCrater}. Thus, the meeting will have more focus than the previous meetings where 40 or more sites have been discussed. Here, we will ultimately vote on four points related to the site (1) Diversity: Can multiple rock units be observed? (2) Context: are they found in a well understood framework? What will we know ahead of time about the locale? What will we know about its connection to its region/ the rest of Mars?(3) Was the site a habitable environment? (on the basis of both geomorphology and mineralogy?) and (4) Preservation potential: If it was habitable, could we preserve signs of that habitability?
The first day began with some good engineering news. The project manager assured us that all of the current sites can be reached with single target specification, mitigating the need for a complicated pairing of landing sites with possible safer backups. Also, the need for a 'safe haven' has disappeared, so the selection process has been significantly simplified since the second landing site workshop. The landing site safety evaluation team also bring the news that all seven of the candidate sites areacceptable at 95% success level. There is some site to site variability in the margin of safety, it is small and is outweighed by remaining uncertainties that affect all of the sites.
The schedule for the first day is arranged in two parts. In the morning, we hear substantial discussion of terrestrial perspectives on habitability and biosignature preservation. The challenges of finding ancient life onEarth are substantive (though somewhat different than on Mars); the record of life on early Earth is radically limited by dynamic resurfacing of the planet by plate tectonics. Even where they are found Archean rocks alsotend to have been beat up (by temperature, pressure, and metamorphism).Thus, many locations where people have thought to find early life it isvery controversial. The key message of these talks is (1) sedimentary rocks are good, preferably shallow water sediments (virtually all biosignature preservation potential is in sedimentary rocks); (2) isolating possible biosignatures from oxidative degradation is important (sequestration is very important); (3) a source-to-sink framework for landing sites very important if we are to actually understand MSL resultsin context.
The second task of the day is to discuss two specific landing sites, which happen to be right next to each other (but substantially different): Miyamoto and S. Meridiani. Miyamoto crater is a 100+ km Noachian basinwith common exposures of phyllosilicate clays in much of its landing ellipse, and possible signs of inverted channnels. The proponent of this site (Horton Newsom) argued that there is evidence that some of these clays may be fluvial as well, but there is no clear evidence of this connection. Much of the criticism of this site during the discussion focuses on actual evidence that this location was habitable, its limitedexposed section, and the disconnect between the phyllosilicates in this site and its somewhat tenuous evidence for fluvial activity (inverted materials which Horton claims are inverted channels).
The second of day one's two landing sites is S. Meridiani. Effectively,this landing ellipse is drawn on exactly the same sulfate rock units that the MER Opportunity rover has been driving around on (although perhaps at a different point in the stratigraphic section). The good news about this site is that we are absolutely sure that we can land on these rocks safely. The real science target in S. Meridiani are a variety of phyllosilicates that appear to be in bedrock just outside of the ellipse. Thus, you get diversity from landing directly on sulfates and then driving to clays. Sandra Wiseman (the proponent of this site) argues that these phyllosilicates are essentially the oldest materials in this location, which were then cut by later valleys. In the discussion, there is a lot of focus on the unknown origin for the phyllosilicates. Could they simply be ejecta from Miyamoto? Are they really layered compositionally? Many of the challenges are about its stratigraphic context.
So that's pretty much the results of the first day. Things are almost certainly going to get more contentious as we discuss the other five sites. We're putting votes off until Wednesday afternoon so that's when the real fight will come out -- though the people running the workshop keep telling us that its not a competition, just a search for the bestsite.
I wanted to give you some perspective of the room as well. The chairs are hilariously wrapped with some sort of stretchy polyester fabric and are really silly looking. The room is a bit bigger than the last meeting (thankfully), but we have rapidly run out of coffee in the hotel provided vats both mornings. Many of the speakers have had single slides with missing images -- a result of people's powerpoint files being incompatible with the projection computer. Always worth thinking about this sort of thing when NASA put people on the Moon. :)
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