Missions
Mars Exploration Rovers: Spirt & Opportunity

Mars Exploration Rovers: Spirit and Opportunity
Opportunity
- Launched on July 7, 2003
- Enabled by Radioisotope Heater Units
- Still actively explore the surface of Mars
Spirit
- Launched on June 10, 2003
- Enabled by Radioisotope Heater Units
- Roved the surface of Mars for more than six years
Heating provided by:
- Eight RHUs each
Goals: Spirit and its twin Opportunity were designed to study the history of climate and water at sites on Mars where conditions may once have been favorable to life. Each rover is equipped with a suite of science instruments to read the geologic record at each site, to investigate what role water played there and to determine how suitable the conditions would have been for life. The rovers are solar powered, but their mission has been enabled by the use of radioisotope heater units.
Accomplishments: Both rovers far exceeded their design specifications and returned science results that transformed our understanding of Mars. Both rovers discovered strong evidence for liquid water on Mars in the distant past.
Spirit uncovered strong evidence that Mars was much wetter than it is now in a silica patch apparently produced by hot springs or steam vents.
Opportunity has returned dramatic evidence that its area of Mars stayed wet for an extended period of time long ago, with conditions that could have been suitable for sustaining microbial life. Opportunity also has analyzed exposed rock layers recording how environmental conditions changed over time.