I'm interested in planetary materials, including their early evolution in the solar system, re-creating their exotic properties in the lab, and extracting them sustainably as space resources.
Dec 11, 2:28pm: Ancient Hydrated Silicates in the Martian Deep: Crustal Density, Water Budget, and Astrobiology. 2018 AGU Fall Meeting, Walter E. Washington Convention Center 206.
1. Carbonaceous muds (Recent abstract).
2. Martian clay formation and noble gas sequestration in the pre-Noachian (Recent publication).
3. High fidelity regolith simulants (Recent publication).
I had the fortune to present at the 2nd workshop for the Mars 2020 landing site selection process last month. Our site, the Nili Fossae Trough, is now among eight remaining sites that will be studied in detail before the third workshop early in 2017:
During the same process for Mars Curiosity, a deep rift emerged between what can be called ‘morphologic’ landing sites versus ‘mineralogic’ landing sites. Morphologic sites tend to be younger in age, with distinct sedimentary layering visible from orbit. Mineralogic sites are rich in alteration minerals and ancient in age, but lack the geologic context needed to fully understand them from orbit. Morphology won out with the controversial selection of Gale Crater, buoyed by a key report of the working group chartered by the MSL project scientist.
That rift has returned this time in a more nuanced form: deltas versus non-deltas. Four of the final eight sites feature deltaic environments: Eberswalde, Holden, SW Melas, and Jezero. Jezero in particular is interesting because its deltas drew sediment from the carbonate and clay-rich Nili Fossae region; however, it’s also the most dangerous site to land and traverse at, and may be culled sooner rather than later for engineering reasons. The other three are more classic ‘morphologic’ sites that bear quite some similarity to Gale.
The appeal of deltaic environments on Mars is their potential, as demonstrated on Earth, to concentrate and preserve organic molecules. This has borne fruit with Curiosity’s success in detecting martian organics in lake sediments at Gale. However, I think an important caveat must be emphasized here. The organics that Curiosity found are simple organic molecules, the kind that cannot be distinguished from those that fall to the surface via meteorites. These do not constitute biosignatures, which must be clear indicators of life. A major goal of the Mars 2020 rover is to seek biosignatures specifically, and simple chlorinated hydrocarbons do not meet this goal. If instead we relaxed the goal to include these types of compounds, then a more effective (and orders of magnitude cheaper) mission would be to the deserts of Morocco, where martian organics are readily found inside meteorites delivered free of charge from the red planet.
There’s no disputing that a trip to a martian delta would likely yield organic molecules, but a deeper question needs to be asked of each of the eight possible landing sites: is there any reason to think that life itself would have been present in the environments recorded in their rock records? This can be laid out like so:
(1) Life is present > (2) Preservation mechanism exists > (3) Biosignature created
It’s a flaw of logic to focus all attention on (2) while ignoring (1), because (1) is really what matters here, even though it’s a tougher question to answer. No biosignatures would be found in a hypothetical preservation environment with perfect fidelity, if the only organic input to that environment is derived from chondritic infall. This is similar to the misguided focus on habitability with no concern for origins of life that plagues the planetary science community. Hopefully we can break out of this narrow focus on organic preservation, and think harder about where and when life could have been present on Mars.