Mars Rovers Exceed 1-Year Mark -- And Expectations

John Roach
for National Geographic News

Updated January 24, 2005

A year ago today scientists erupted in riotous applause when a robotic rover named Opportunity safely bounced to a stop on Mars. Today, long after the end of its 90-day initial mission, the rover continues to dazzle the world with insight into Mars's wet past.

"I never, ever would have imagined the opportunity to literally be standing here a year later and saying yet again, 'We're back, and we're still on Mars,'" departing NASA administrator Sean O'Keefe told reporters gathered for a celebration earlier this month. The occasion was to mark the one-year anniversary of the successful landing and deployment of Spirit, Opportunity's twin rover which plopped down on to the opposite side of the red planet on January 3, 2004.

The rovers were sent to Mars to hunt for signs that water—a key ingredient in the recipe for life—once existed on the planet. With the support of satellites in Mars orbit and an army of scientists on Earth, the rovers didn't disappoint.

Examining a variety of Martian rocks with drills, magnifying glasses, and a suite of high-tech sniffers, the rovers have found minerals, chemical signatures, and rocks with textures and shapes that are suggestive of a watery past.

"[The] discovery that Mars once had a large amount of surface water is indeed a profound finding," O'Keefe said. "And what it tells us is that the climate, the atmosphere of our closest neighbor, was once dramatically different and perhaps conducive to life."

Steve Squyres, the Cornell University-based principal investigator for the Mars Exploration Rover Mission, was at JPL for the celebration. He concurred that the year's events and discoveries have been remarkable.

"I think, by any reckoning, the lasting legacy of this mission is going to turn out to be the recognition by people here on this planet that our sister planet Mars once had habitable conditions on its surface," he said. "And what that meant for the origin of life, what it meant for the evolution of life—that's for the future Mars program to tell."

Prolonged Life

The rovers were designed to work for 90 days and to travel little more than half a mile (one kilometer). They've far exceeded those parameters and will continue to operate until some mission-ending mishap occurs, according to program scientists.

"These rovers are in great shape for their age right now," said Jim Erickson, project manager of the Mars Exploration Rover Mission at JPL. "As they continue on through their respective anniversaries, they're continuing to get new records under their belt."

A year into their exploration, the rovers have driven nearly four miles (six kilometers) and combined and sent to Earth more than 62,000 images and reams of additional science data.

Spirit's only major "health" crisis came eight days after it bounced to a stop in Gusev Crater. A glitch in its memory software left the rover silent. But mission engineers were able to update the software and send the rover on its way.

For its part, Opportunity started off with a bad shoulder joint—a problem with a heater that engineers soon worked around.

Luck has been kind to the rovers, Erickson said. They are getting more power and their solar panels are staying cleaner. Plus, the nighttime temperatures are not nearly as frigid as anticipated. "It's all for the good. We're able to continue on, and we're in a strong position to continue exploration with both of the rovers," he said.

Today Spirit is roaming up in the Columbia Hills, more than 2 miles (3.2 kilometers) from its landing site. The rover recently examined a rock named "Wishstone," which contains significant deposits of phosphorous that may have been left behind from water percolating up through the Martian surface.

"Spirit is in excellent health as the team looks forward to celebrating the anniversary of Opportunity's landing on January 24," JPL reported on its Web site ten days ago.

At the end of December, after six months of study, Opportunity climbed out of Endurance Crater and made tracks across the Meridiani plains.

The rover's first stop was at the heat shield it jettisoned during landing. "Opportunity is healthy," the mission Web site noted on January 14. "It acquired microscopic images of the fractured edge of the heat-shield wreckage and began a detailed investigation of an intriguing, pitted rock a few meters to the north, called 'Heat Shield Rock.'"

Mission engineers are curious to learn how the heat shield behaved as it passed through the Martian atmosphere. Such information may prove crucial to planning for future missions, Erickson said.

After examining the heat shield, Opportunity will zigzag between craters as it heads south toward an intriguing feature named Vostok. Squyres, the Mars rover mission's principal investigator, said Vostok may be an eroded impact crater.

Breakthrough of the Year

The journal Science named the discoveries of NASA's Mars Exploration Rovers Mission the "Breakthrough of the Year" in its December 17, 2004, issue.

"The two Mars rovers confirmed what many scientists have long suspected: Billions of years ago, enough water pooled on the surface of Earth's neighbor long enough to allow the possibility for life," noted the science journal.

The rovers were designed to look for signs of past water, not life, but scientists consider water a prerequisite for life.

Analysis of the rocks and sediments of Mars suggest that the water was acidic, salty, and probably came and went on time scales of thousands of years—hardly ideal conditions for life to originate.

On Earth, however, scientists have found hardy microbial life thriving just about everywhere they've looked, including in lakes high in Chile's Atacama Desert that are considered similar to ancient lakes on Mars that may have existed.

Future missions to the red planet will continue to probe the life question, though a definitive answer may be years distant. The closest possibility for a mission that returns Martian samples to Earth would come next decade, according to NASA planners.

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