How did this unusual Martian rock form? This atypical two-toned rock was photographed in March 2007 by Mars Exploration Rover Spirit as it continued its mission of discovery on the red planet. Finding unusual rocks is not unusual for Spirit or its twin rover Opportunity.
How did this unusual Martian rock form? This atypical two-toned rock was photographed in March 2007 by Mars Exploration Rover Spirit as it continued its mission of discovery on the red planet. Finding unusual rocks is not unusual for Spirit or its twin rover Opportunity. Having investigated alien terrain and found clear evidence that part of Mars had a wet past, the Earth-launched rovers are now entering their third spectacular year exploring the red planet.Image credit: NASA/JPL/Cornell