Mars Rover Spirit's Days May Be Numbered

This article was written by CNET News.com's Jennifer Guevin.

One of NASA's seemingly immortal Mars rovers might soon be at the end of its days.

The Spirit rover had been cruising around the Red Planet, along with its companion, Opportunity, since they both arrived six years ago this month. (Spirit landed on January 3, 2004, while Opportunity landed on January 24 of that year.) Their mission to send back photos and data about the Martian surface was expected to last a mere 90 days. Instead, the two traveling research bots blew away all expectations, continuing their treks year after year.

However, scientists warn that Spirit's most recent anniversary might have been its last. The rover became stuck in a sand trap nine months ago, after one of its wheels broke through a crusty layer of soil into a pocket of loose sand. It wasn't the first time Spirit has run into trouble. Its right-front wheel stopped working in 2006, and a month ago, its right-rear wheel began to fail.

Scientists continue to try to get Spirit out of the sand pit, but so far those efforts have been unsuccessful. Wiggling the wheels and rotating them very slowly have resulted in only minimal improvements in the situation. Next, NASA could try having Spirit drive backward or use its robotic arm to sculpt the ground directly in front of one of its wheels. But expectations are low, and on Wednesday, NASA said it is running out of maneuvers to attempt.

All of this is worsened by the fact that the rovers are solar-powered, which means they need to collect sunlight with their onboard solar panels in order to power their operations and create enough heat to survive the frigid winters on Mars.

In the southern hemisphere of Mars, where Spirit is trapped, it is currently autumn--so precious sunlight is declining with each day. The rover also happens to have settled into a position that's far from ideal for collecting what sunlight remains. It's tilted five degrees to the south, but the sun is in the north.

Even if Spirit cannot escape its sandy prison, all isn't necessarily lost--at least for now. Ray Arvidson, who's from Washington University in St. Louis and who also serves as deputy principal investigator for the rovers, says that if scientists can improve Spirit's tilt, it might be able to collect enough power to keep doing research right where it is.

"We can study the interior of Mars, monitor the weather, and continue examining the interesting deposits uncovered by Spirit's wheels," said Arvidson in a statement.

If the team cannot free Spirit or improve its angle, NASA estimates that the rover will run out of power in May--if not sooner.

Meanwhile, Spirit's sister rover, Opportunity, keeps rolling on. It is currently making the seven-mile trek from Mars' Victoria crater to the Endeavour crater to continue its research.

By Jennifer Guevin