Nine years after landing on Mars for a three-month mission, the aging NASA rover Opportunity may be poised to find more evidence that water once flowed on the Red Planet.
The rover's first discovery of clues that water once flowed on Mars was announced in March 2004. But scientists later deemed it would have been acid-rich and not very conducive to life. Now, situated on the rim of a 14-mile-wide crater named Endeavour, the 400-pound rover may have stumbled upon an ancient region on Mars where the water was once neutral, maybe even drinkable.
"It's like a brand-new mission," said John Callas, project manager for Opportunity at the Jet Propulsion Laboratory in La Cañada Flintridge. "We could spend years exploring this area."
On Jan. 25, 2004, Opportunity landed inside Eagle Crater on a region of Mars called Meridiani Planum. Its twin rover, Spirit, landed on an opposite side of the planet but lost contact with Earth in 2010 after becoming stuck in soil. Opportunity, still successfully operating and communicating with scientists and engineers, was maneuvered more than 22 miles to reach the prime chunk of real estate.
Images from the Mars Reconnaissance Orbiter suggest that Endeavour may hold clays, which usually need water to form. It's the kind of material that scientists hope JPL's newest and most powerful rover, Curiosity, will find.
Opportunity does have limitations: Its miniature thermal emission spectrometer and Mossbauer spectrometer, two key mineralogy instruments, are broken.
But scientists will still be able to gauge what kind of rocks the rover rolls by looking at details like texture and layering, said JPL project scientist Matt Golombek. "We can do what a geologist does in the field."
The rover still has the power to clear dust off rocks and take scenic panoramic and close-up shots of the Red Planet.
The earthbound rover drivers, like scientists, have to work around Opportunity's handicaps .
The rover's front right steering actuator is jammed and its shoulder joint has issues analogous to arthritis. Ashley Stoupe, who was a driver on Spirit and now on Opportunity, said she has learned to turn the rover without moving its problem areas.
Drivers can't go for a joy ride on the planet. They must take their time to ensure that the senior rover isn't slipping on rocks or driving too deep into a crater. Going from target to target takes more time, but it's worth it to keep the rover running, Stoupe said.
"We are always looking for new ways of driving that keep the other wheels in good health," she said.
Mars experiences dramatic changes in atmospheric pressure and rough, cold winters. Opportunity has survived it all, powered only by solar energy.
"It still has all of its basic capabilities, which is just amazing," Stoupe said. "It's incredible that they're able to last so long in these environments."
Golombek, who has worked on the mission since the early planning stages, said no one at JPL expected Opportunity to last through 2013. "It's amazing," he said.
Some 40 scientists and engineers at the space agency currently work part time or full time on the mission.
As the rover has lasted well beyond its expiration date, mission team members know that any day could be its last. Still, scientists are taking advantage of the fact that it's alive now and is looking down at an ancient crater.
Callas said it's difficult to predict when the rover will stop working.
"Tomorrow, the rover might not be there," he said. "It might experience a catastrophic electronic failure and it dies, right there. Each day we're a day closer to the end, but I don't know when the end is."