Orbiter helps rover

LOS ANGELES – Scientists said Friday they were plotting the next move for the Mars rover Opportunity, which reached the edge of a deep and geologically rich crater last week after a marathon trek.

The six-wheel robot spent its first week at Victoria Crater acting like a tourist, snapping pictures of the half-mile-wide jagged crevasse filled with dramatic cliffs of thickly layered rocks, which hold clues about the Martian past.

New aerial images snapped by the Mars Reconnaissance Orbiter, which slipped into orbit last year, gave scientists a bird’s-eye view of the crater and evidence of erosion around the rim. In one image, the rover appeared as a speck with its wheel tracks visible in the soil.

By studying close-ups of the rover’s surroundings and aerial shots taken by the orbiter, scientists hope to zero in on the safest route for the rover to enter and probe the inner walls before it goes bust.

“This vehicle could die at any minute. We have no guarantee that it’s going to last,” rover principal investigator Steve Squyres of Cornell University said at a news conference.

Opportunity drove for 21 months to reach Victoria, which is five times bigger than another crater the rover spent six months studying in 2004.

Victoria’s exposed rock layers promise to shed light on whether the place could have been hospitable to life. A preliminary analysis showed distinct patterns in the sedimentary rock layers, suggesting the area experienced fluctuating climate, scientists said.

Opportunity and its twin, Spirit, both uncovered geologic evidence of past water activity on the planet since their landings two years ago. The Reconnaissance Orbiter is the most powerful spacecraft to circle Mars.