Journal of Geophysical Research: Planets
Results From the Mars Exploration Rover Spirit and Opportunity Missions
The NASA Mars Exploration Rovers, Spirit and Opportunity, have been exploring terrains on Gusev Crater and Meridiani Planum, respectively, since January 2004. The primary missions lasted 90 Mars days (sols), with a first extended mission defined for an additional 90 sols. The rovers and scientific instruments have operated well beyond their Ã¢ÂÂwarrantiesÃ¢ÂÂ and continue to make important discoveries about the current state and past history of Mars.