Just one mile before touchdown, the spacecraft played its trump card: Audacity, a rocket-powered platform designed specifically to shuttle Curiosity to the Martian surface. (Previous Mars rovers had landed with air bags, but the one-ton Curiosity was far too porky for that approach.) Audacity used eight engines to slow to a leisurely 1.7 miles per hour as the rover, connected by a bridle, dangled beneath. Audacity kept dropping until it sensed the rover was stable on the ground. Then it cut itself loose, throttled up its rockets, and flung itself skyward, crash-landing 2,100 feet away. Curiosity arrived in perfect shape, ready to get to work.