In late 2005, instruments on the Mars Exploration Rover (MER) Spirit observed a pair of outcrops dubbed Comanche and Comanche Spur at the base of Haskin Ridge in the Columbia Hills of Gusev crater. Observations from the Mssbauer spectrometer (MB) and Miniature Thermal Emission Spectrometer (Mini-TES) were clearly different from the olivine-rich rocks that mantle the ridge, but the identity of one or more anomalous components was enigmatic [McSween et al., 2008; Morris et al., 2008]. The possibility of a Fe-Mg carbonate component was considered for the MB data although not published because the data were not unique to this phase (R. V. Morris, 2008 personal communication). A later reanalysis of the elemental data from the Alpha Particle X-ray Spectrometer (APXS) presented evidence for significant excess light elements consistent with CO2 and hence carbonate. Mini-TES spectra were encumbered by contributions from dust that had contaminated the instruments pointing mirror [Ruff et al., 2006], precluding a robust assessment of the carbonate possibility. Following the implementation of a viable mirror-dust correction, the Comanche spectra were revisited years later, and presented clear and compelling evidence for a Mg-Fe carbonate component that could be as much as a third of the total mineral abundance. More than four years after Spirit visited the Comanche outcrops, observations from all three instruments supported the identification of abundant Mg-Fe carbonate (16-34 wt%) [Morris et al., 2010]. The discovery of carbonate-rich rocks in Gusev crater contributes new evidence in the long running debate about a warmer, wetter ancient Mars [e.g., Harvey, 2010]. This new discovery using old data also highlights our motivation to continue investigating Spirits Mini-TES data set.
|Effective start/end date||6/1/12 → 5/31/17|
- NASA: Goddard Space Flight Center: $349,323.00