Biology
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p32a..03a&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P32A-03
Biology
[5220] Planetary Sciences: Astrobiology / Hydrothermal Systems And Weathering On Other Planets, [5400] Planetary Sciences: Solid Surface Planets, [5419] Planetary Sciences: Solid Surface Planets / Hydrology And Fluvial Processes, [5470] Planetary Sciences: Solid Surface Planets / Surface Materials And Properties
Scientific paper
The Mars Science Laboratory (MSL) rover Curiosity will land at the ~155 km diameter Gale Crater (4.6°S 137.2°E) in early August of 2012. The landing ellipse is centered in the northwestern floor of the crater on an alluvial fan composed of material from the crater rim. MSL will sample this material and test the hypothesis that the fan was deposited by flowing liquid water, and then drive south toward the base of the >5km tall central mound of layered rocks. Along this traverse, the smooth, low-thermal-inertia surface of the alluvial fan transitions to a fractured, layered, and spectrally neutral high thermal inertia unit. MSL will be able to assess the interpretation of this unit as cemented alluvial material and determine the cementing agent. Fresh craters in the high thermal inertia unit are important targets for MSL because their ejecta has had less exposure to the harsh radiation environment of the surface which can destroy biomarkers. Continuing south, MSL will descend across a short scarp where the units of the crater floor have eroded to expose the underlying basal unit of the mound. This erosion has formed ridged mesas interpreted to be lithified aeolian bedforms that are part of a widespread "mound-skirting" unit. MSL will test the hypothesis that this unit comprises debris shed from the mound during an early stage of erosion. The heavily fractured basal unit is partially obscured by relatively young mafic dunes, which will provide information about modern aeolian processes on Mars. After analyzing the basal unit and the dunes, MSL will begin climbing the layered rocks of the mound, beginning with a light-toned ridge which shows spectral evidence of hydrated sulfates. Beyond this ridge, the rover will encounter a phyllosilicate-bearing surface exposed in a trough paralleling the ridge. These lower mound layers are the primary targets of the MSL traverse. MSL will test the hypothesis that the lower mound sediments were deposited in a lacustrine setting, and will determine the changing conditions that led to the transition from phyllosilicate to sulfate deposition. The thick sequence of sulfate-bearing layers is eroded into yardangs and canyons, but HiRISE slope maps indicate that there are several potentially traversable routes up the mound. One key feature within the sulfate-bearing strata is a filled channel carved into the mound, which ends at an outcrop of the mound-skirting unit that overlies the phyllosilicate-sulfate contact. MSL will study the material filling this channel, which may be representative of upper mound materials, and then continue to climb to the southwest. Higher within the sulfate-bearing strata, MSL will test the hypothesis that the large polygonal ridges visible in HiRISE data are erosion-resistant cemented fractures resulting from groundwater interaction with the mound rocks. A reasonable goal for the primary mission traverse is the unconformable contact between the sulfate-bearing rocks and a lens of light-toned, finely layered yardang-forming material. Extended mission targets include non-planar layers, a high-thermal inertia unit, and branching fill features on the western mound, as well as the extensive stratigraphy of the upper mound.
Anderson Benjamin R.
Bell Jon F.
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