Postcards from Mars: Insights into Martian Geochemical Processes from the Curiosity Rover

Abstract

With the successful landing of the Mars Curiosity Rover in August 2012, we now have the most capable geochemical laboratory ever to travel to another planet roving Mars' Gale crater. The geochemical instrument suite includes the Chemistry Camera (ChemCam), which uses a laser to vaporize geologic targets and performs atomic emission spectroscopy on the vapor from distances of up to 7m. This provides a geochemical surveying capability that enables rapid identification of unique specimens and accumulation of a large set of rock and fines compositions as the rover traverses. The Alpha Particle X-ray Spectrometer (APXS) provides high quality "bulk" elemental analyses for major, minor and a few trace elements through a touch deployment on the surface of a rock or soil, and is an upgraded version of similar instruments previously flown to Mars. The addition of x-ray diffraction through the Chemistry and Mineralogy (CheMin) instrument and volatile, isotope, and organic analyses with the Sample Analysis at Mars (SAM) instrument suite, give Curiosity the capability to assess the geochemical history of the planet more deeply than previously possible. Both CheMin and SAM accept sieved fines from either Curiosity's scoop or drill. To date, sampling has occurred at the Rocknest aeolian drift deposit and a fine-grained mudstone called John Klein. At Rocknest, CheMin found a mix of primary igneous minerals and amorphous materials. SAM found that Rocknest fines contain significant bound volatiles that can be released upon heating, largely associated with the amorphous material. Because APXS and ChemCam data support the fines being representative of those found at other sites on Mars, Curiosity results show that martian fines are a good source of water, CO2 and other volatiles that could be leveraged by living organisms, including future human explorers. At John Klein, early results are consistent with an ancient aqueous habitable environment. Analyses of isotopes and organics also provide exciting windows into martian habitability and volatile evolution. These early geochemical results will be discussed.

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