Volume: 01, Issue: 02
High-resolution image of Gusev Crater with topographic information, gathered from the Mars Global Surveyor and Mars Odyssey orbiters.
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Gusev Crater, the designated landing site for the first rover, as seen from NASA Viking images.
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High-resolution image of Meridiani Planum with topographic information, gathered from the Mars Global Surveyor and Mars Odyssey orbiters.
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Meridiani Planum, the second designated landing site, as seen from NASA Viking images.
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Other Articles in This Issue:
Mars Orbiter Camera Team Begins Daily Picture Postings
Classroom Exploration of the Oceans: An Online Teacher Workshop Series

NASA Chooses Mars Rover Landing Sites

NASA has selected two geologically diverse landing sites on Mars’ surface for its twin robotic rovers to explore early next year. The Mars Exploration Rovers will examine the sites for evidence of past water activity and life-sustaining environmental conditions.

The first rover will target Gusev Crater, located 15 degrees south of the Martian equator, which appears to have once held a lake. The second will target Meridiani Planum, two degrees south of the equator and halfway around the planet from Gusev, which contains deposits of gray hematite, an iron oxide mineral.

Which rover will target which site is still tentative and could change up until one month after the launch of the first rover, scheduled to occur in June. One rover will parachute to an airbag-cushioned landing on Jan. 4, 2004 and the second on Jan. 25, 2004.

NASA scientists and engineers spent a great deal of effort evaluating images of potential landing sites from two NASA spacecraft orbiting Mars, examining topography, composition, rockiness and geological context. According to Dr. Matt Golombeck of Jet Propulsion Laboratory (JPL) in Pasadena, Calif., candidate sites had to be near the equator, low in elevation, not too steep, not too rocky and not too dusty, among other criteria. More than 100 Mars scientists participated in the examination of 155 potential sites.

The chosen sites met all essential criteria and showed promising scientific value.

“Meridiani and Gusev both show powerful evidence of past liquid water, but in very different ways,” said Dr. Steve Squyres, principal investigator for the rovers’ science toolkit and a geologist at Cornell University in Ithica, N.Y. “Meridiani has a chemical signature of past water. Gray hematite is usually, but not always, produced in an environment where there is liquid water. At Gusev, you’ve got a big hole right in the ground with a dry riverbed going right into it. There had to have been a lake in Gusev Crater at some point. They are fabulous sites, and they complement one another because they’re so different.”

Besides choosing potential landing sites for their scientific value, the scientists and engineers had to weigh the safety concerns of each potential landing site.

“Landing on Mars is very difficult, and it’s harder on some parts of the planet than others,” said Dr. Ed Weiler, NASA associate administrator for space science in Washington, D.C. “In choosing where to go, we need to balance science value with engineering safety considerations at the landing sites. The sites we have chosen provide such balance.”

Each rover will spend at least 90 Martian days (92 Earth days) examining their landing sites. The solar-powered rovers will likely suffer diminished power supplies after approximately 90 days due to dust accumulation on the solar arrays.

“It should be a very busy and exciting time after landing for the scientists analyzing the wealth of new data from the ground,” said Dr. Cathy Weitz, Mars Exploration Rover program scientist at NASA Headquarters.

The twin Mars Exploration Rover spacecraft are currently being held at NASA’s Kennedy Space Center, Fla., in preparation for launch. JPL, a division of the California Institute of Technology in Pasadena, built the rovers and manages the project for NASA’s Office of Space Science in Washington, D.C.

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