In Montreal, Steve Squyres describes new adventures of the Mars rovers

By Blaine P. Friedlander Jr.

MONTREAL -- The Mars rovers, Spirit and Opportunity, are heading into two new and very different adventures in their pursuit of further geological evidence that water once flowed on the planet.

Spirit is speeding like a clipper ship toward the now not-so-distant Columbia Hills from its landing site at Gusev crater. Its twin, Opportunity, is surveying the rim along the football stadium-sized Endurance crater on the Meridiani plain for a potentially perilous pathway into the crater to investigate a huge, cantilevered bedrock outcrop.

Squyres

"We are contemplating the wisdom of actually going into the crater," confirmed Steve Squyres, Cornell professor of astronomy and the principal scientific investigator for the Mars rover mission, speaking at a press conference at the American Geophysical Union Joint Assembly here May 17.

Mission scientists and engineers, said Squyres, are trying to determine the crater-slope grade before sending Opportunity into the enormous hole. After finishing the first of a three-part crater-rim survey, the rover is moving toward two new positions on the rim so that its two panoramic cameras can take images of possible routes into the crater along pathways with names Karatepe Ingress-Egress and Kalahari Ingress-Egress.

Another route receiving particular attention, said Squyres, is Larry's Leap, named for planetary scientist Larry Soderblom, the father of Cornell graduate student and mission researcher Jason Soderblom. The elder Soderblom, who works for the U.S. Geological Survey, advocates sending Opportunity down the eponymous slope.

To help in making the decision, said Squyres, an indoor slope -- much like a large skateboard ramp, replete with sand and rocks -- is being planned at NASA's Jet Propulsion Laboratory, Pasadena, Calif., to assess how a test rover can cope with climbing a 20-degree gradient. "This is right at the edge of what it can do," commented Squyres.

Meanwhile, on the other side of Mars, Spirit is handling the journey across the rocky landscape like an Olympic athlete. The vehicle, which is on the verge of reaching twice its guaranteed life span, was built to travel just 600 meters (656 yards). The Columbia Hills are more than 2.5 kilometers (1.5 miles) from Spirit's landing site.

On some days early in the mission, Spirit traveled 25 meters (27 yards). Now the vehicle averages about 120 meters (131 yards) a day. Squyres said that Spirit set a new one-day travel record last week when it traveled124 meters (136 yards) in a single day. Recently uploaded software "has made the rover faster and more courageous," he said. "We have really set sail."

Spirit is now less than a kilometer from Columbia Hills, and it could arrive there by mid June. "The hills are looming larger in the windshield," Squyres said. "The hills are beginning to look really, really big, and there's a lot of interesting stuff in those hills."

Squyres reminded the media that the terrain could be tricky, particularly with a semi-autonomous rover making its own driving decisions. "That's not a parking lot we're crossing. It's a hilly, rock-strewn terrain. This kind of pace bodes well for having lots of rover capability left when we get to the hills," he said.

En route to Columbia Hills, Spirit is not ignoring its scientific work. Squyres and his science team have scheduled three hours of science each sol (Martian day), in a routine now called a "sol quartet." Every sol -- equal to one Earth day plus 39 minutes and 35 seconds -- one of four of the rover's main scientific instruments obtains a measurement. It could be observing the Martian atmosphere with the mini-thermal emission spectrometer on one sol and using the Mössbauer spectrometer the next. Each major instrument gets a turn in the rotation every fourth sol.

The Martian winter is still several months away. But already there is less light for the solar panels, and that means less energy for the rovers. Regardless of the impending change of season, Squyres said, "The vehicles are just in outstanding health. They're better than when they first landed."