1 of 10Image
shadow on MarsNASA's robotic space explorers, the Mars rovers Spirit and Opportunity, have done the unexpected by surviving for a full Martian year (687 Earth days) on the red planet. When Spirit first landed on Jan. 3, 2004, scientists hoped that the rovers would last 90 sols, or Martian days.
Spirit's shadow and robotic arm are captured in this image. In early December 2005, researchers reported that Opportunity's robotic arm may be permanently damaged.
grains of sand
Both rovers together have taken more than 130,000 pictures of Mars. This image of an area 1.2 inches across was taken by Spirit's microscopic imager. The scale can show features as small as 4 one-thousandths of an inch.