January 3, 2009--NASA's Mars rovers Sprit and Opportunity are still rolling five years after they landed on the red planet. Spirit celebrated its anniversary on January 3, 2009; Opportunity's "birthday" is three weeks later.

Few could have predicted that the robot explorers would still be operational. "The American taxpayer was told three months for each rover was the prime mission plan," Ed Weiler, associate administrator for NASA's Science Mission Directorate, said in a statement. "The twins have worked almost 20 times that long."

This westward view of Mars, above, was captured by Spirit in November 2007.