Mars exploration rover mobility development

The Mars Exploration Rover (MER) Project was launched in mid-2000 to land two mobile exploration platforms at different science targets on the red planet. The centerpiece of each mission is the rover and its scientific payload. Spirit and Opportunity are identical vehicles, and each carries the same science payload and engineering subsystems. NASA's current Mars program is once again focused on missions to the Martian surface to answer fundamental questions of the extent Mars ever supported a liquid water environment on its surface, and hence the planet's ability to have sustained life