Can Spirit be revived

The Spirit rover, currently out of commission on the surface of Mars, could be awakened in the coming weeks.

Speaking to Space.com, John Callas, NASA's head of the Mars rover program at the Jet Propulsion Laboratory, said that the "increasing" sunlight on the Mars surface is giving him and his team some hope that it can put the solar-powered Spirit rover back on the job.

"As long as [sunlight is increasing], we will do all we can to increase the chances of hearing from the rover again," Callas told the publication.

However, Callas acknowledged that his team is losing some hope with each passing day. He said the fact that it is now spring on Mars and the team hasn't heard anything back from Spirit is "concerning." He told Space.com that "each day that goes by, it's one more tick downward in our optimism for the rover."

That's certainly sobering news for those that have been following Spirit all these years.

The rover first landed on Mars in 2004, and was expected to search for evidence of water for a period of three months. Still going strong after three months, NASA continued operating Spirit for about six years until communication was lost last March. Since then, NASA has been trying to revive the rover, which became immobile last January due to damage to two of its wheels.

But even if Spirit doesn't come back, its legacy is impressive. As Callas pointed out to Space.com, Spirit found "physical conditions on Mars" that were similar to "geysers in Yellowstone, or deep ocean vents, which are thriving systems here on Earth." It found that there was "liquid water on Mars, but there were [also] energy sources coincident with that liquid water."

Callas' talk on Spirit comes just a couple days after NASA announced that another rover, Opportunity, will be spending the next two months exploring the Santa Maria crater on the Martian landscape. Opportunity landed on Mars on January 25, 2004.