Second Mars Rover Completes Primary Mission

The second of NASA's twin Mars rovers (search) wrapped up its primary mission Monday, the 90th full day on the Red Planet. Opportunity (search) will probably keep working through at least September.

"We're ready, willing and able to carry on with the extended mission," said deputy project manager Jim Erickson of NASA's Jet Propulsion Laboratory (search).

As of Monday, Opportunity and its twin, Spirit, have completed all the tasks NASA required before the space agency would consider the double mission a success.

Each identical rover traveled at least 1,980 feet, took stereo and color panoramas of its surroundings, drove to at least eight locations and operated simultaneously with its twin for 60 days.

Spirit is already well into its own extended mission; Monday was its 112th day on Mars, halfway around the planet from its twin.

The goal of the $835 million double mission is to scour Mars for geologic evidence the planet once was a wetter place capable of sustaining life. Opportunity has found that evidence.

On the opposite side of Mars, Spirit has found evidence of only limited amounts of past moisture.