Enhanced groundwater flow on and below Vera Rubin ridge, the Murray Formation, Gale Crater: Evidence from thermochemical modeling

NASAs Mars Science Laboratory Curiosity rover has been exploring Vera Rubin ridge (VRR), part of the Murray formation in Gale crater, Mars, between sol 1809 and 2302. Evidence for Fe-oxides and phyllosilicates in mineralogical and geochemical data for this region was returned by Curiosity [1-5]. We applied thermochemical modeling to con-strain the formation conditions of the phyllosilicate-hematite assemblage identified on and below VRR. Average alteration compositions for the Murray formation on and below VRR were derived using CheMin and APXS data. These compositions were reacted with Gale Portage Water (GPW) between 25100 C and for 10% and 50% Fe3+/Fetot of the host rock [6]. Here we summarize models run at 50 C and 10% Fe3+/Fetot for alteration compositions derived from Murray host rock compositions

SOPHIA: A mineralogical simulant for phyllosilicate terrains at the <i>Rosalind Franklin</i> landing site, Oxia Planum, Mars

The phyllosilicate-bearing martian plain, Oxia Planum, is the proposed landing site for the Rosalind Franklin rover mission, scheduled to launch in 2028. Rosalind Franklin which will search for signs of past or present life on Mars. Terrestrial analogue sites and simulants can be used to test instruments analogous to those on Rosalind Franklin, however no simulant for Oxia Planum currently exists. In anticipation of this mission, a simulant - SOPHIA (Simulant for Oxia Planum: Hydrated, Igneous, and Amorphous) - representative of the local mineralogy at Oxia Planum has been developed for biosignature and mineralogy experiments, which will assist in interpreting data returned by the rover. The simulant is derived from orbital observations of Oxia Planum and its catchment area. As no in situ data is available for Oxia Planum, mineralogy from other comparable sites on Mars was used to design the simulant including orbital data from Arabia Terra and Mawrth Vallis and in situ data collected from Gale crater. The mineralogy, chemistry and physical properties of the simulant were characterised using standard laboratory techniques (SEM-EDS, XRF, XRD).Techniques analogous to rover instruments (Raman spectroscopy, Near-IR spectroscopy analogous to the Raman laser spectrometer and ISEM and MicrOmega instruments) were also used. The simulant is rich in Fe/Mg phyllosilicates with additional primary igneous and other alteration minerals and is an appropriate spectral and mineralogical analogue for Oxia Planum

Mineralogical Investigation of Mg-Sulfate at the Canaima Drill Site, Gale Crater, Mars

For the first time on Mars, the crystalline magnesium-sulfate mineral starkeyite (MgSO4‧4H2O) was definitively identified using the CheMin X-ray diffraction instrument at Gale crater. At the Canaima drill site, starkeyite along with amorphous MgSO4‧nH2O are among the “polyhydrated Mg-sulfates” interpreted in orbital reflectance spectra. Mg-sulfates are good climate indicators as they are very responsive to changes in temperature and relative humidity. We hypothesize that, through evaporation, Mg-sulfates formed at the end of brine evolution when ion concentrations became saturated and precipitated on the surface or near sub-surface as either epsomite or meridianiite. These minerals were subsequently dehydrated later to starkeyite and amorphous MgSO4‧nH2O in response to a drier Mars. At Canaima, starkeyite is stable and would form during the warmer Mars summers. Due to very slow kinetics at the low Mars winter temperatures, starkeyite and amorphous MgSO4‧nH2O would be resistant to recrystallize to more hydrous forms and thus likely persist year-round. During the course of analyses, starkeyite transforms into amorphous MgSO4‧nH2O inside the rover body due to the elevated temperature and greatly reduced relative humidity compared to the martian surface at the Canaima drill site. It is possible that crystalline sulfate minerals existed in earlier samples measured by CheMin but altered inside the rover before they could be analyzed. Starkeyite is most likely prevalent in the subsurface, whereas both starkeyite and amorphous MgSO4‧nH2O are likely present on the surface as starkeyite could partially transform into amorphous MgSO4‧nH2O due to direct solar heating. © 2023. The Authors.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Curiosity at Gale Crater, Mars: Characterization and analysis of the rocknest sand shadow

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations