Listen: New Mars Photos Wow NASA
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The Red Planet as seen by the Hubble space telescope.
A black and white view of the martian horizon, taken by the Opportunity rover. Scientists believe the soil surrounding the rover may hold proof that water once flowed on Mars.
Spirit's first color image of Mars.
An artist's depiction of the Mars Exploration Rover on the Red Planet. The plan is for each rover to spend 90 days slowly crawling over the planet's surface, stopping to take pictures and soil and rock measurements.
The second Mars rover, Opportunity, has safely touched down on the Red Planet and is already sending back photos. NASA officials are delighted at the second successful landing on Mars in a month.
Opportunity's twin rover, Spirit, landed Jan. 4 on the other side of the planet. Spirit has experienced software difficulties, but NASA engineers are slowly solving them, as NPR's Joe Palca reports.
After several days of round-the-clock work on Spirit, NASA mission managers pulled away Saturday to focus on Opportunity. It bounced down on schedule shortly after midnight on the U.S. East Coast to cheers at the Jet Propulsion Laboratory in Pasadena, Calif.
Spirit began malfunctioning earlier this week, going silent at times and sending back junk data at others. Engineers at NASA's Jet Propulsion Lab in Pasadena, Calif., have re-established successful communications with Spirit, but are still unsure about the cause of the rover's malfunction.
Mission managers say the problems with Spirit will make them even more conservative about operating Opportunity. But they're delighted at Sunday's prompt response from the second robotic explorer.
NASA is hoping to use the twin rovers to find evidence that water once flowed on Mars, an indication that life may have existed on the Red Planet.