Showing papers by "S. W. Squyres published in 2010"

Mineralogy and chemistry of cobbles at Meridiani Planum, Mars, investigated by the Mars Exploration Rover Opportunity

Abstract: Numerous loose rocks with dimensions of a few centimeters to tens of centimeters and with no obvious physical relationship to outcrop rocks have been observed along the traverse of the Mars Exploration Rover Opportunity. To date, about a dozen of these rocks have been analyzed with Opportunity’s contact instruments, providing information about elemental chemistry (Alpha Particle X‐ray Spectrometer), iron mineralogy and oxidation states (Mossbauer Spectrometer) and texture (Microscopic Imager). These "cobbles" appear to be impact related, and three distinct groups can be identified on the basis of chemistry and mineralogy. The first group comprises bright fragments of the sulfate‐rich bedrock that are compositionally and texturally indistinguishable from outcrop rocks. All other cobbles are dark and are divided into two groups, referred to as the "Barberton group" and the "Arkansas group," after the first specimen of each that was encountered by Opportunity. Barberton group cobbles are interpreted as meteorites with an overall chemistry and mineralogy consistent with a mesosiderite silicate clast composition. Arkansas group cobbles appear to be related to Meridiani outcrop and contain an additional basaltic component. They have brecciated textures, pointing to an impact‐related origin during which local bedrock and basaltic material were mixed.

Spring awakening planned for Mars rover Spirit.

Abstract: Your ill-timed ‘obituary’, in News, for the Mars rover Spirit (Nature 463, 600; 2010) brings to mind Mark Twain’s saying that reports of his death had been exaggerated. Spirit is alive and well — albeit with limited mobility — and is still returning scientific data from Mars more than six years after landing. As the Martian winter advances in the months ahead, we expect Spirit to hibernate (not die) by cutting off its communication with Earth and conserving electrical power. Once the Martian spring arrives, we expect Spirit to re-awaken and start doing science once again. We plan to continue using Spirit’s wheels to try to reposition the vehicle. But even if very little motion is achieved, we can still carry out an extended science campaign, including tracking Spirit’s radio signal to find out whether the core of Mars is molten or solid. The day will come when an obituary can be written that lauds Spirit’s scientific accomplishments. But that day may not arrive for some time yet. Steve Squyres Mars Exploration Rover Project, Space Sciences Building, Cornell University, Ithaca, New York 14853, USA e-mail: squyres@astro.cornell.edu