Astrophysicist Stephen Hawking is assisted off the bus by caregiver Monica Guy as Chairman and CEO of Zero Gravity Peter Diamandis, second from left , waits on the tarmac at the Kennedy Space Center landing strip in Cape Canaveral, Fla. Thursday, April 26, 2007. A jet carrying Hawking later took off from the Kennedy Space Center on a flight to simulate zero gravity. (Xinhua/AFP Photo)