Firouz Naderi, Mars Program Manager In his office, Dr. Firouz Naderi takes a moment to reflect on the success of the rovers and the challenges along the way. Image Credit: NASA/JPL Link to Full Res

"Arthritis" in Spirit's Wheel

"Spirit's right front wheel is having arthritis problems," says Firouz Naderi, Mars Exploration Program Manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. He adds with humor, "Just like a car on Earth has to go in for a 30,000-mile check-up, Spirit is coming up on its 3,000-meter checkup, and probably needs a lube job-but no tire rotation this time!"

"Lube job coming right up!

The rover, which has set distance records for travel on the surface of another planet, may essentially need a "lube job" on its wheel, as the lubricant there may not be flowing properly. Over the next few weeks, engineers will be studying whether, by heating up the lubricant in the wheel, the problem may be eliminated. Even if not, the rover is fully able to drive on five, and, jokes Naderi, maybe even on three . . . so long as they're not all on the same side!

	Spirit's "Arthritic" Front Wheel The sun partly shines on Spirit's right wheel, as its robotic arm reaches out to study minerals on Mars. Image Credit: NASA/JPL Link to Full Res

Extra-credit science, even with a challenged wheel

All kidding aside, he is sensitive to the fact that the rovers are essentially on borrowed time, getting lots of "extra credit science" accomplished.

Both rovers successfully accomplished their 90-day primary missions, and are still performing well. In fact, the rovers seem to be so healthy overall that engineers even contemplate that, as winter comes to the rovers' landing sites, they might be able to put them in "hibernation," and even revive them in the spring.

That would be quite a feat, and no one is quite sure it's possible, but you can't blame the optimism of a team who has met with such success.

	Naderi Studies Spherules Containing Hematite Firouz Naderi, Mars Exploration Program Manager at JPL, at work in his office. Image Credit: NASA/JPL Link to Full Res

The rovers perform beyond their mission-success requirements

As Spirit approaches its half-year on Mars, it has driven more than five times its mission requirement of 600 meters (0.37 miles), and continues to climb into Columbia Hills.

Meanwhile, Opportunity is peering farther back into martian history with each layer in the wall of Endurance Crater it studies.

Both rovers have found hematite, a mineral that often forms in the presence of water, and scientists have confirmed that water once soaked Opportunity's landing site area in Meridiani Planum.

Discussing the Challenges and Excitement of the Mission Firouz Naderi and Gentry Lee (in ball cap) have an informal discussion in "mission control" prior to Spirit's landing, not knowing at the time how well the rover would do. Link to Full Res

Unimagined success: a rover capable of climbing around mountains and another down into craters

"You know," says Naderi, "Prior to landing, I compared the challenges of Mars exploration to the perils of mountain climbing—when there are problems on the mountain, you have two choices: either go back to the base camp or rally up your courage, regain your foothold, and keep pressing on toward the summit." Mars, says Naderi with the firmness of one who understands the risks, is not about base camps. But, shaking his head in a bit of relaxed wonder, he adds, "In my wildest dreams, I never imagined we'd have one rover actually capable of climbing around mountains, and another descending down slopes into deep craters."

	A Moment of Mission Enjoyment Gentry Lee (center) smiles broadly with enthusiasm along with Project Manager Pete Theisinger (left), scientist Matt Golombek (right), and engineer Adam Steltzner. Image Credit: NASA/JPL Link to Full Res

Enjoying every day on Mars past the rovers' 90-day "warranty"

"I can't believe everyone on the planet is not riveted to our daily progress," adds JPL's Gentry Lee, whose energy, if it could be tapped, could supply a whole fleet of rovers through a martian winter. "This mission is everything we've ever wanted. Each day, we move the rovers a little farther, putting new terrain and new potential discoveries right in front of their ‘noses.'" Involved in Mars missions since the Viking days in the 1970s and early ‘80s, when two orbiters and static landers conducted intensive scientific studies of Mars, Lee has spent a career waiting for the technological capability of roving into unseen territory, literally peering around the next bend, over the next horizon.

As enthusiastic as they are about the rovers' successes, both Naderi and Lee know that each additional day past the initial 90-day "warranty" is a gift to the team and all who continue to follow the mission. "Any day," says Naderi, "we're aware that something critical could break. Until then, we're going to have fun as engineers finding ways to work around problems like the one with Spirit's wheel, while delighting in the new discoveries that come each day."