Mars Rover Sets Sights on Biggest Crater Yet

After a two-year stay in Mar's Victoria Crater, NASA's Opportunity rover will be moving on to an even bigger playground.

The rover has set its sights on a crater called Endeavour, more than 20 times larger than Victoria. To get there, Opportunity will have to drive approximately 7 miles (12 km) to the southeast, matching the total distance it has traveled since landing on Mars in January 2004. The rover climbed out of Victoria Crater earlier this month.

"We may not get there, but it is scientifically the right direction to go anyway," said Steve Squyres of Cornell University, principal investigator for the science instruments on Opportunity and its robotic twin Spirit. "This crater is staggeringly large compared to anything we've seen before."

The Endeavour crater, a bowl 13.7 miles (22 km) across, should offer the chance to study a much deeper stack of rock layers than those Opportunity saw in Victoria Crater.

"I would love to see that view from the rim," Squyres said. "But even if we never get there, as we move southward we expect to be getting to younger and younger layers of rock on the surface. Also, there are large craters to the south that we think are sources of cobbles that we want to examine out on the plain. Some of the cobbles are samples of layers deeper than Opportunity will ever see, and we expect to find more cobbles as we head toward the south."

Just getting to the new crater itself will be a feat. The rover team estimated that even if Opportunity travels about 110 yards (about 100 meters) each day, the journey could take two years.

"This is a bolder, more aggressive objective than we have had before," said John Callas, the project manager for both Mars rovers at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's tremendously exciting. It's new science. It's the next great challenge for these robotic explorers."

Opportunity, like Spirit, is well past its expected lifetime on Mars, and might not keep working long enough to reach the crater. However, two new resources not available during the 4-mile (6.4-km) drive toward Victoria Crater in 2005 and 2006 are expected to aid in this new trek.

One boon will be satellite images of the ground taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, which arrived in Mars orbit in 2006. This tool can capture details smaller than the rover itself.

"HiRISE allows us to identify drive paths and potential hazards on the scale of the rover along the route," Callas said. "This is a great example of how different parts of NASA's Mars Exploration Program reinforce each other."

Other advantages come from a new version of flight software uplinked to Opportunity and Spirit in 2006, boosting their ability to autonomously choose routes and avoid hazards such as sand dunes.

During its first year on Mars, Opportunity found geological evidence that the area where it landed had surface and underground water in the distant past. The rover's explorations since have added information about how that environment changed over time. Finding rock layers above or below the layers already examined adds windows into later or earlier periods of time.

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