Rover Spirit Reaches Summit of Martian Hills

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GOLDEN, Colo. — NASA’s Mars rover Spirit is experiencing the high life now that it has reached the top of Husband Hill after a slow, year-long climb.

Perched some 82 meters — about the height of the Statue of Liberty — above the plains of its Gusev Crater landing site, Spirit has returned images of stunning new vistas that include a potential winter refuge as the Martian seasons progress, mission scientists said Sept. 1 during a press conference at NASA’s Washington headquarters.

“That’s no Mt. Everest, but it’s a heck of a climb for our little rover,” Steve Squyres, principal investigator of the rover’s science mission at Cornell University in Ithaca, New York, told reporters. “When we first touched down at Gusev Crater on Jan. 4, 2004, the Columbia Hills looked impossibly far away.”

Spirit spent 591 Martian days roving across the 3 kilometers between its landing point and the summit of Husband Hill, one of a network of rises in the Columbia Hills chain. One Martian day, or sol, is about 24 hours and 40 minutes.

The rover reached the base of the Columbia Hills in June 2004. That chain of hills was so named to honor the astronauts who died in the Feb. 1, 2003 accident that destroyed the shuttle Columbia. The layered rocks that Spirit later found in the Columbia Hills were changed by water in the planet’s ancient past. The new terrain of the hills was also a welcome change for researchers, who until then had found almost nothing but the same, basalt rocks — the most basic type of rock — day after day of exploring the Gusev Crater.

“The rocks in the Columbia Hills are nothing like the basalt on the plains,” said Ray Arvidson, deputy principal scientist for the rover science mission at Washington University in St. Louis, Missouri, during the press conference. “Water was involved in practically every one that we’ve seen so far.”

Squyres said Spirit engineers and researchers would spend a week to 10 days discussing when to leave the summit, though the rover will likely not stay atop Husband Hill for many months.

Researchers already have picked out a long-distance target dubbed Home Plate located south of Spirit’s current location. A north-facing slope on the side of another hill, known as McCool Hill, may offer a prime spot to weather the Martian winter since the rover’s solar arrays would be angled toward the Sun to collect the most sunlight.

“The deciding factor will be how good the geology is,” Squyres said of the time it will take to descend Husband Hill. “I think going downhill has the potential to go a bit faster, it’s easier to go downhill with these vehicles than going up.”

While Spirit took the high road at Gusev, its robotic twin Opportunity has made steady progress across the rocky etched terrain of Meridiani Planum on the other side of Mars.

Despite a still unexplained software glitch, in which Opportunity reset itself Aug. 21, the rover has given researchers their first glimpse into an odd coating — known as a rind — that covers some rocks at Meridiani.

“We’ve been very curious to figure out what they are,” Squyres said.

Opportunity used its robotic arm-mounted microscopic imager and rock-grinding abrasion tool to compare a bare rock dubbed Strawberry with a coated area called Lemon Rind. While essentially identical in most respects, Lemon Rind contains higher levels of sodium and chlorine than Strawberry.

“One possibility is that it’s the last layer to form,” Squyres said of Lemon Rind’s coating, adding that the rind also may have formed much later, after both rocks were deposited at Meridiani. “It speaks to yet another water episode.”

Engineers have slowly been recertifying Opportunity since the software was reset — even as it continues its science operations, researchers said.

“I think the reset itself was more of an annoyance,” said Jacob Matijevic, who heads the rover engineering team at NASA’s Jet Propulsion Laboratory . “I’d sure like to know what exactly took place.”

Spirit and Opportunity are currently funded through December 2006, with scientific targets set in six-month sections, NASA’s Mars Exploration Program chief Doug McCuistion said.

While the rovers show some signs of age — the rock-grinding bits of Spirit’s rock abrasion tool are so worn they’re only useful for brushing targets clean — they are still generating ample supplies of power, rover handlers said.

“As long as these vehicles remain healthy and continue on their science return we’ll continue,” McCuistion said. “An asset on the [Martian] surface like this is invaluable … and we certainly don’t want to cut them off.