Time was, spacecraft regularly exceeded expectations: Apollo 13's Lunar Module acting as a lifeboat, Pioneer and Voyager probes leaving the solar system and still transmitting...

Looks like they're building them that way again! Spirit and Opportunity, the two golfcart-sized Mars rovers, touched down on that planet's rusty surface a year ago.

They were originally supposed to last only a few months -- but they just keep going. Spirit just discovered a new kind of rock. And they both are credited with the #1 science discovery of the year -- that Mars was once a water world.