November 2004 Meeting

Monday, November 8, 2004
6:00 - 7:30 pm

Pellissippi State Technical Community College
10915 Hardin Valley Road, Knoxville
Lamar Alexander Building
Room 223


Geology of the Martian Surface
First Results from the Mars Exploration Rovers Sprit and Opportunity

Jeff Moersch
Assistant Professor
Remote Sensing & Planetary Geology
Department of Earth and Planetary Sciences
University of Tennessee


In summer, 2003, the United States launched two unmanned robotic explorers, dubbed "Spirit" and "Opportunity" to explore the surface of Mars. Each rover carried an international payload of instruments that enabled it to act as a robotic field geologist, under the command of a science team back on Earth. Both rovers landed successfully in January, 2004, and began their primary tasks of trying to unravel the geologic histories of their landing sites, specifically in regard to the role liquid water may have played. Spirit's landing site is in Gusev Crater, a large (~120km diameter) impact basin that has been postulated to have been a lake in the earliest period of Martian history. To date, Spirit has found no overt evidence for a lake there, but more subtle manifestations of liquid water have been found, such as physical and chemical alteration of the volcanic rocks that dominate the landscape. Opportunity landed in an area called Meridiani Planum that had been identified from previous orbiter missions as having the spectral signature of specular hematite, which on Earth usually forms in the presence of liquid water. Fortuitously, Opportunity landed in a small impact crater with exposed rock outcrop laid out just a few meters away. Crossbedded and festooned layering, high sulfate abundances, and small spherules of specular hematite (dubbed "blueberries") at this outcrop and another in a much larger crater investigated by Opportunity all point to a rich history of flowing liquid water interacting with the surface at this site. The design life of the rovers for operations on the Martian surface was only three months. Both rovers are currently working well at more than three times that duration, and may continue to operate and explore their environs much longer.


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