'Grand challenges' spur grand results

In October 2004 SpaceShipOne roared into space (twice) - the first privately funded spacecraft ever to reach suborbit, nearly 70 miles above Earth. A year later, "Stanley," a Volkswagen Touareg modified by Stanford University students, rumbled across some 130 miles of desert without a human driver, navigating the rough terrain guided by computer programs and sensors. In both cases, the designers were motivated to be the first to do something - and to win a cash prize. The Ansari X PRIZE for spaceflight paid out $10 million from a private foundation. The DARPA Grand Challenge for robotic vehicles awarded $2 million, put up by the federal Defense Advanced Research Projects Agency.