The life of a Mars rover is probably bit like that of Wall-E at the start of the Pixar movie: a lot of lonely treks in dutiful fulfillment of a mission through the remains of a planet's earlier days.
The rovers Spirit and Opportunity may not be Hollywood icons, but they have done NASA proud. And in just the last day or so, Opportunity hit yet another milestone--it now holds the record for the longest active service on the surface of Mars, surpassing the mark of six years, 116 days (in Earth time) set by the Viking 1 lander, which arrived on the Red Planet in the summer of 1976.
Like the two rovers, the Viking spacecraft (there were two of them as well) were designed to work for only about 90 days. Viking 2 hung in for about four years.
The Martian winter solstice passed just over a week ago, which bodes well for the continued operation of the solar-powered Opportunity. That seasonal mark has even raised hopes for the revival of Spirit, which hasn't been heard from since March 22 and which got itself bogged down in a sort of sand trap. On top of that, NASA staff weren't able to orient Spirit so that its solar panels were at a favorable angle.
Spirit arrived on Mars three weeks earlier than Opportunity in January 2004, so if it can rouse itself, it would take over the duration record.
Opportunity is headed "across a vast plain" marked by surface ripples toward the Endeavour Crater, which lies about eight long miles away. As the Martian days get longer, Opportunity should have more and more energy for its trek. Scientists are excited about getting to Endeavour, which according to orbital observations, holds clay minerals--yet another tantalizing suggestion that Mars might once have sustained life.
"Those minerals form under wet conditions more neutral than the wet, acidic environment that formed the sulfates we've found with Opportunity," said Cornell University's Steve Squyres, the principal investigator for Opportunity and Spirit, in a statement. "The clay minerals at Endeavour speak to a time when the chemistry was much friendlier to life than the environments that formed the minerals Opportunity has seen so far. We want to get there to learn their context. Was there flowing water? Were there steam vents? Hot springs? We want to find out."
The next rover: Curiosity
Meanwhile, back on Earth, NASA's Jet Propulsion Laboratory is making progress on a bigger rover, called Curiosity, that is expected to arrive on Mars about two years from now.
On Thursday, the JPL announced that it has set its windows for Curiosity's launch and arrival. The rocket carrying the rover is expected to blast off between November 25 and December 18, 2011, and the rover would then touch down on Mars between August 6 and 20, 2012. The specific Earth-to-Mars trajectory was selected to take best advantage of information from Mars orbiters during Curiosity's descent and landing.
At the time of Curiosity's touchdown on Mars, the orbiter Odyssey--which will be in view of both Earth and Curiosity--will relay the data stream from the rover's descent gear to NASA scientists back home. It performed a similar "bent pipe" relay when the Phoenix lander arrived at Mars in 2008.
Known more formally as the Mars Science Laboratory, Curiosity won't be solar powered--instead, it will run on nuclear energy like the Viking landers before it. The big new rover, standing up to 7 feet tall, is intended to be in service on Mars for nearly two Earth years, looking for signs of microbial activity.
And maybe, like its predecessors, it will keep going for a long time thereafter.
Correction, 6:40 p.m. PDT: This story initially gave the wrong name for the rover that set the duration record. It was the Opportunity.