Jack Farmer

Samples from the Rocknest aeolian deposit were heated to ~835°C under helium flow and evolved gases analyzed by Curiosity's Sample Analysis at Mars instrument suite. H2O, SO2, CO2, and O2 were the major gases released. Water abundance (1.5 to 3 weight percent) and release temperature suggest that H2O is bound within an amorphous component of the sample. Decomposition of fine-grained Fe or Mg carbonate is the likely source of much of the evolved CO2. Evolved O2 is coincident with the release of Cl, suggesting that oxygen is produced from thermal decomposition of an oxychloride compound. Elevated δD values are consistent with recent atmospheric exchange. Carbon isotopes indicate multiple carbon sources in the fines. Several simple organic compounds were detected, but they are not definitively martian in origin.

Abstract Curiosity investigated active eolian sands near linear dunes during Phase 2 of the Bagnold Dunes campaign in Gale crater, Mars. Ogunquit Beach, a sample scooped from a large‐ripple trough within the Mount Desert Island ripple field and delivered to the Chemistry and Mineralogy (CheMin) X‐ray diffraction instrument, is dominated by basaltic igneous minerals and X‐ray amorphous materials. CheMin mineralogy of the Gobabeb sample acquired at a large‐ripple crest on the Namib barchan dune during Phase 1 is similar to Ogunquit Beach. Ogunquit Beach, however, contains more plagioclase and Gobabeb contains more olivine. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)‐based estimates of mineralogy at the optical surface of Namib Dune and Mount Desert Island demonstrate that surface sands are enriched in olivine and depleted in plagioclase over Mount Desert Island relative to Namib Dune. Differences between CheMin‐derived and CRISM‐derived mineralogies suggest sorting by grain size on bedform to dune field scales. Crystal chemistry from CheMin suggests contributions from multiple igneous sources and the local bedrock.

Abstract Microbial communities developing on modern clastic sedimentary surfaces of arid lands are dominated by phototrophic microorganisms that form a variety of characteristic “microbially induced sedimentary structures” (MISS) through their interactions with detrital sedimentary grains, aided by secretions of extracellular polymeric substances and other organic materials. In this study, we describe modern MISS from unvegetated arid topsoils and compare them with fossil MISS found within decimeter- to meter-thick sedimentary sequences of Mesoproterozoic siliciclastic outcrops of the Dripping Spring Quartzite formation of the Apache Group in central Arizona, USA. These sequences contain numerous bedding plane exposures with desiccation surfaces including polygonal cracks, curls, and chips. Repetition of these structures within stratigraphic sequences indicates recurring episodes of subaerial exposure. Some of these MISS contain cellular microfossils that exhibit morphological adaptations for surviving desiccation. The strong similarities between modern and ancient MISS in this study provide additional criteria for recognizing morphological biosignatures of terrestrial microbial communities in ancient deposits. Our results provide compelling evidence for the presence of land-based microbial communities by the Mesoproterozoic (∼1200 Ma). The association of MISS features further suggests that the primary producers that had colonized Mesoproterozoic land surfaces were likely desiccation-adapted photosynthetic microbes, similar to modern desert soil crust communities.

Astronauts on long-duration lunar missions will need the capability to high-grade their samples - to select the highest value samples for transport to Earth - and to leave others on the Moon. Instruments that may be useful for such high-grading are under development. Instruments are also being developed for possible use on future lunar robotic landers, for lunar field work, and for more sophisticated analyses at a lunar outpost. The Johnson Space Center Astromaterials acquisition and Curation Office (JSC Curation) wll support such instrument testing by providing lunar sample ground truth.

Final Document is attached. Introduction: The Mars Science Laboratory Curi-osity rover landed in Gale crater in August 2012 to search for habitable enironments preserved in the rocks and sediments on the lower slopes of Aeolis Mons (i.e., Mount Sharp). Along the traverse, Curiosity encountered an active aeolian sand sheet, informally known as the Bagnold dune field. Orbital CRISM vis/near-IR data suggest that there are varying abun-dances of olivine and pyroxene across the dune field, where the barchan dunes on the edge of the dune field have stronger olivine signatures than the linear dunes.