When NASA’s next wheeled robot—the Mars Science Laboratory—rockets skyward in 2009, the mega-rover will carry the largest, most sophisticated array of science gear ever shot to the martian surface. Far more robust and powerful than those smaller robotic look-alikes now laboring on Mars—Spirit and Opportunity—the Mars Science Laboratory (MSL) is intended to turn a new page in planetary exploration. But here’s the issue at hand: Where to land the hunk of high-tech machinery; deciding the ideal spot that’s safe but also maximizes the rover’s chances to help figure out if Mars ever was—or is today—an abode for life.