Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars

Abstract

International audienceThe ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration

Rapidly reversible redox transformation in nanophase manganese oxides at room temperature triggered by changes in hydration

“…The surface of Mars currently has a very thin atmosphere, but the possibility of mineral surface hydration under Martian conditions was investigated in the laboratory (12,13) and recently detected directly at Gale Crater, Mars (14). There are great diurnal temperature differences and sheltered basins with subsequent transient melting of ice (15)(16)(17) and craters where the atmospheric pressure is higher than average (18,19).…”

Mechanism of atomic force microscopy imaging of three-dimensional hydration structures at a solid-liquid interface

“…Hydration plays fundamental roles in biomolecular functions [1][2][3], crystal growth [4], soil wetting [5], and catalytic reactions [6]. Despite the wide success of diffraction and spectroscopy techniques in investigating hydration structures at the nanoscale [7][8][9][10][11][12][13], molecular level detail of water distributions at critical inhomogeneous interfaces remains elusive.…”

A Conspicuous Clay Ovoid in Nakhla: Evidence for Subsurface Hydrothermal Alteration on Mars with Implications for Astrobiology

“…In one particular instance-in a paleolake system within Jezero Crater-the clays are reported to be smectite-rich, although these materials (along with coexisting iron oxides or hydroxides) are considered to be allochthonous sediments (Ehlmann et al, 2008a). Furthermore, clay minerals (particularly trioctahedral smectites) have now been detected in martian sedimentary rocks at Yellowknife Bay (Gale Crater) by the MSL Curiosity rover (Vaniman et al, 2014), and a significant component of amorphous material has been identified in Gale Crater (Bish et al, 2013;Blake et al, 2013;Meslin et al, 2013). Consequently, the potential for discovering that clay minerals might also have been widespread in the subsurface of early Mars (Ehlmann et al, 2011) is now higher, and this is important from the standpoint of understanding subsurface/ subaqueous processes on Mars and providing clues to the origin of such clays.…”

“…Fluvial conglomerates have also been identified in Gale Crater with the Mast Camera (Mastcam) of the Mars Science Laboratory (MSL) Curiosity rover, indicating that extended aqueous flows once took place on the surface of the planet in that region (Williams et al, 2013). Furthermore, the Sample Analysis at Mars (SAM) instrument on board the MSL Curiosity rover recently measured significant quantities (1.5-3 wt %) of an H 2 O component released from the amorphous fines of the Rocknest eolian deposit of Gale Crater (Leshin et al, 2013), among other volatiles such as CO 2 , SO 2 , and O 2 .…”

“…Remote sensing of the martian surface by orbiting spacecraft and in situ investigations conducted by landers and rovers has contributed to these investigations and improved our understanding of the planet (e.g., Bibring et al, 2006Bibring et al, , 2007Bish et al, 2013;Blake et al, 2013). The first major aim was to discover evidence of past or present water on the surface of Mars and then, more importantly, to search for the presence of life.…”