Starting in 2004, NASA's Mars Exploration Rover mission sent two unmanned robotic probes, Spirit and Opportunity, crawling across the Red Planet's surface. The six-wheeled vehicles found strong evidence of past flowing water, including apparent ancient lakeshore deposits.
Their mission was designed to last 90 days. However, both probes vastly exceeded their predicted lifetimes and in 2009, though showing signs of age, they were still responding to mission control's commands.
Photo: Artist's impression of Spirit on the surface of Mars (NASA)
Two hardy robotic vehicles crawl across Mars.
Sir Patrick Moore and Chris Lintott discuss the Mars rovers.
Sir Patrick Moore and his co-presenter Dr Chris Lintott discuss the Mars rovers, Spirit and Opportunity. At the time they spoke, Opportunity had just reached Victoria crater and had been photographed from orbit by the Mars Reconnaissance Orbiter.
NASA's Mars Exploration Rover (MER) mission is an ongoing robotic space mission involving two Mars rovers, Spirit and Opportunity, exploring the planet Mars. It began in 2003 with the sending of the two rovers: MER-A Spirit and MER-B Opportunity—to explore the Martian surface and geology. Both rovers outlived their planned missions of 90 Martian solar days by far. MER-A Spirit was active until 2010. MER-B Opportunity is still active. The success of the two MERs led to another mission, sending a bigger rover Curiosity in 2012.