After landing on the surface of Mars nine years ago, the Mars Exploration Rover Spirit used its panoramic camera to take this color image. At the time, it was the highest resolution image ever taken on the surface of another planet, with a full size of 4,000 by 3,000 pixels.
Three weeks later, on January 25, 2004, the Opportunity rover landed. In the intervening years, the two robotic explorers have returned an astounding 303,802 raw images, amassing an unprecedented library of photos from the surface of another planet.
This gallery presents just a few of the hundreds of thousands of images provided by the twin rovers.