Noted physicist Stephen Hawking greets the media after his arrival at the Kennedy Space Center Shuttle Landing Facility for his first zero-gravity flight. The flight will be aboard a modified Boeing 727 aircraft owned by Zero Gravity Corp., a commercial company licensed to provide the public with weightless flight experiences. Hawking developed amyotrophic lateral sclerosis disease in the 1960s, a type of motor neuron disease which would cost him the loss of almost all neuromuscular control. At the celebration of his 65th birthday on January 8 this year, Hawking announced his plans for a zero-gravity flight to prepare for a sub-orbital space flight in 2009 on Virgin Galactic's space service. Photo credit: NASA/Kim Shiflett