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After a cautious "toe-dip" into the alcove known as Duck Bay, the NASA rover Opportunity started its full descent into Mars's Victoria Crater yesterday.

Experts hope the planned three-month mission will offer new insight into the red planet's geologic past.

The Mars rover Opportunity began its full descent into the red planet's Victoria Crater on September 13, 2007. Experts hope the planned three-month mission will offer new clues to the red planet's geologic past.

The rover's front hazard-identification camera snapped this wide-angle view looking into the crater at the end of the first leg of its trip, 20 feet (6 meters) inside the rim.

The rover's first destination will be a layer of light-colored rock exposed along the crater's inner slope, which experts say could offer a glimpse of what the Martian surface was made of millions of years ago.

"The crater has what looks like a bathtub ring," said John Callas, the Mars rover project manager at NASA's Jet Propulsion Laboratory in Pasadena, California.

"Scientists think it is the ancient surface of Mars from before the impact that created the crater."

The first leg of the descent brought the rover about 20 feet (6 meters) inside the rim.

Mission managers are now programming the rover to drive toward the rock layer, Callas said, and the robot might reach the formation over the weekend.

Dusty Setback

Opportunity's current exploration inside Victoria Crater should last for about three months, although "the duration will be determined by the science," Callas said.

The descent, originally slated to start in July, was postponed by a massive dust storm on Mars.

At one point the swirling dust covered about 7 million square miles (18 million square kilometers)—covering Opportunity and its twin rover Spirit .

The storm blocked sunlight, starving the rovers' solar arrays and sparking concerns that a lack of power might cause the hardy robots to shut down for good.

But as the dust cleared, NASA was able to bring the rovers back to operational power levels, and Opportunity now has "good-enough energy for what needs to be done," Callas said.

And NASA scientists are confident that the earlier toe-dip proved that the rover can make it back over the rippled rim of the crater at the mission's end.

"As long as the rover stays healthy," Callas said, "we expect it can get back out, no problem."

英文原文版权归 NationalGeographic Victoria Jaggard

图片版权归 NASA/JPL-Caltech

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