The Mars Science Laboratory rover Curiosity has sampled sediments that appear to fit the major goal of the mission – to determine whether Mars may have harbored any habitable environments. The rover’s first ever drill sample was from a mudstone target named John Klein, and follows the first ever scoop sample, of an eolian “sand shadow” named Rocknest. Both samples were delivered to the internal laboratory instruments on Curiosity, the Sample Analysis at Mars instrument (“SAM”, which is comprised of a Quadrupole Mass Spectrometer, a Gas Chromatograph, and a Tunable Laser Spectrometer) and the “CheMin” Chemistry and Mineralogy instrument that determines mineralogy using X-ray diffraction. PSI Senior Scientist Dave Vaniman is the deputy principal investigator for the CheMin instrument.
The image above shows the John Klein sample in the scoop of the sampling system after the drill powder was sieved to a size of less than 150 nanometers and before portions were delivered to SAM and to CheMin. The drill powder from John Klein is gray and distinctly different from the red scooped powder of Rocknest, some of which still adheres to the back wall of the scoop. The gray color of John Klein is one indication that it is not as extensively oxidized as typical Mars surface materials. Indeed one of the major findings from the John Klein sediment is that it encompasses a range of oxidation states, something required of an environment that could support organisms that might obtain their energy from oxidation-reduction processes. Another major finding, determined by the CheMin instrument, is the presence of at least 20 percent clay minerals (phyllosilicates) in this sediment. The search for clay minerals was a major goal of the MSL mission, since these minerals are often associated with habitable sedimentary environments. The CheMin instrument also detected Ca-sulfate salts that indicate an environment of near-neutral pH, another common marker of an environment favorable for habitability.
