Curiosity is about the size of a mini cooper and is four times more heavy than the Spirit and Opportunity which were launched in 2004. The Curiosity also comes with a larger robot arm, a laser that can split rocks, a weather station, and a percussive drill for drilling rocks. Unlike the Spirit and Opportunity, Curiosity also has on board 10.5 pounds of plutonium-238! Yes, Curiosity is nuclear-powered instead of solar powered like the previous rovers. No sun is required to power the systems on board.