The Mars Exploration Rovers Spirit and Opportunity have been on Mars since January 2004. They were expected to last only 90 days but will work into 2009. The rovers are on opposite sides of Mars. Spirit has returned more than 102,000 images, while Opportunity has returned over 94,000. They have both found metallic meteorites on Mars. Spirit has recorded dust devils in video clips, and Opportunity has analyzed rock layers and found water in the past.