080929 A bigger challenge for Opportunity

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A bigger challenge for Opportunity
BY DR EMILY BALDWIN
ASTRONOMY NOW

Posted: September 29, 2008

Having recently risen from Victoria Crater, NASA’s intrepid Opportunity rover now has a crater 20 times larger set firmly in its sights. At over 10 kilometres away, Opportunity must trek a distance comparable to the total distance it has clocked up since landing on Mars in early 2004 to reach the giant crater known as Endeavour to mission scientists.

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

This aerial view of Opportunity’s domain, made up of around 50 images taken by the Mars Odyssey Orbiter, really puts into perspective the difference in size between Victoria and Endeavour, and the challenge the plucky rover now faces. Image: NASA/JPL/ASU.

Getting there would offer a look inside a 22 kilometre-wide crater, and the chance to probe a much deeper stack of rock layers than those examined in Victoria Crater for the last two years.

"I would love to see that view from the rim," says Squyres. "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."

At 100 metres a day, the rover is unlikely to reach the target crater for another two years, an ambitious goal given that the rovers are showing more and more signs of wear and tear after surviving on the red planet’s surface for well beyond their initial 90 day mission.

"This is a bolder, more aggressive objective than we have had before," says John Callas, the project manager for both Mars rovers. "It's tremendously exciting. It's new science. It's the next great challenge for these robotic explorers."

But two new resources that weren’t available during the 6.5 kilometre drive toward Victoria Crater in 2005 and 2006 could make the journey slightly easier. One is the HiRISE camera onboard the Mars Reconnaissance Orbiter that can identify drive paths and navigate around potential hazards, such as boulders, on the same scale as the rover itself.

"This is a great example of how different parts of NASA's Mars Exploration Program reinforce each other," says Callas.

Another advantage comes 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. As Opportunity now faces the long trek towards Endeavour, it could find rock layers above or below the layers already examined, adding windows into later or earlier periods of time.