So now Piccard has dreamed up a greener--and far gutsier--aviation milestone to conquer: circling the globe in a solar-powered plane. "It would be the purest way to fly," he says. Pure, yes; easy, no, notes engineer Paul MacCready
of AeroVironment Inc., who has consulted Piccard on his new plan--and pinpointed plenty of hurdles. The farthest a pilot has ever flown a solar plane is 163 miles, a record set in 1981 when MacCready's Solar Challenger crossed the English Channel.