This past weekend, NASA's 2004 Mars Exploration Rover, Opportunity, accrued more than 25 miles of driving across the Red Planet, breaking a record previous held by the Soviet Union's Lunokhod 2 Moon rover.

The spotlight has been somewhat stolen from Opportunity since Curiosity, NASA's latest Mars rover, touched down in the Gale Crater in 2012, but this latest accomplishment by the rover is a strong reminder that the decade-old craft is still chugging along.

"Opportunity has driven farther than any other wheeled vehicle on another world," Mars Exploration Rover Project Manager John Callas said in a recent release. "This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance. But what is really important is not how many miles the rover has racked up, but how much exploration and discovery we have accomplished over that distance."

NASA reports that Opportunity had already driven more than 20 miles even before arriving at its last spot for investigation, the western rim of Endeavour Crater, in 2011. There, the rover analyzed minerals and geological formations. NASA's scientists often name landmarks for missions as they go, and have dubbed Opportunity's next mission spot "Marathon Valley," as it is about 6.2 miles away from Endeavour Crater. Once Opportunity reaches this new spot, it will have traveled the distance of an average marathon.

Prior to Curiosity's accomplishment, the Soviet Union's Moon rover Lunokhod 2 had held the record for longest distance traveled on an extra-terrestrial surface, having covered a little more than 24 miles in 1973.

"The Lunokhod missions still stand as two signature accomplishments of what I think of as the first golden age of planetary exploration, the 1960s and '70s," said Steve Squyres, the principal investigator for NASA's twin Mars rovers, Opportunity and Spirit. "We're in a second golden age now, and ... it has been a real honor to follow in their historical wheel tracks."

Still, the "marathon" is not done just yet. While Curiosity has only currently traveled a bit more than five miles since it first landed, it has already exited its "safety zone" within the Gale Crater, and is prepared to traverse more challenging terrain in its search for evidence of ancient life on Mars.