To say the Opportunity rover surpassed NASA's expectations of how long it would last roaming Mars' surface is an understatement.

Marking its 12th year on the Red Planet, Opportunity has dwarfed the initial expectations it would die out after 90 days, according to The San Jose Mercury News. Opportunity landed on Mars Jan. 24, 2004, just weeks after its out-of-commission partner Spirit, which lasted six years.

NASA recently announced Opportunity will be active for its seventh Martian winter.

"Opportunity has stayed very active this winter, in part because the solar arrays have been much cleaner than in the past few winters," John Callas, a project manager for the Mars Exploration Rover Project at NASA's Jet Propulsion Laboratory, said in a press release. "With healthy power levels, we are looking forward to completing the work in Marathon Valley this year and continuing onward with Opportunity."

Mission managers initially though the rovers would not be able to survive more a few months, and projected their batteries to drain due to dust coating their solar panels. A little more than eight and a half years later, NASA landed its third rover on Mars, Curiosity, and is planning to send another one to the Red Planet.

"Twelve years is a very long time to have this sort of a continuous presence," Matt Golombek, Mars rovers project scientist, told The Mercury News. "For a science team to be this involved, on a daily basis, for this long on Mars, is pretty much unprecedented."