>In January 2004, two rovers – Spirit and Opportunity – touched down on the surface of the Red Planet. NASA hoped that one of the two rovers would last for 90 days, but this turned out to be a huge underestimate. Spirit roved the surface for nearly six years before getting stuck in a patch of soft dirt, while Opportunity has lasted well into its 15th year before joining its sibling.
>Before Spirit and Opportunity landed, the accepted picture was that Mars was pretty much dry except for its polar ice caps, and may have always been that way. That was overturned when the rovers found evidence for ancient water on Mars – repeatedly. >Over the course of its mission, Opportunity drove about 45 kilometres, exploring more than 100 craters along its way and weathering bitter cold and numerous dust storms.
>On 10 June, Opportunity sent its last signal to Earth. Since then, operators have frantically sent more than 600 wake-up calls to the rover instructing it to turn on and phone home, testing every kind of spacecraft error that they know how to correct. >Nothing worked. There was no call home. 5499 days into its 90-day mission, Opportunity is finished. “It’s the end of the first great Martian road trip,” says Seibert. >Ultimately, the rovers will be remembered for their incredible longevity. “I thought we might get 6 to 8 months on these things, maybe as much as a year” says Squyres. “If a spacecraft functions for 15 years and dies in one of the biggest dust storms Mars has seen in decades, that’s an honourable death.” http://archive.is/KV6Tu http://archive.is/VctJH