ORLANDO, Fla. (AP) - Astrophysicist Stephen Hawking, who has been confined to a wheelchair for most of his adult life, expects weightlessness to feel like "bliss'' when he goes on a "zero-gravity'' flight Thursday aboard a refitted jet.

"For someone like me whose muscles don't work very well, it will be bliss to be weightless,'' Hawking told The Associated Press in an interview Tuesday.

Hawking, 65, who has Lou Gehrig's disease, will be the first person with a disability to fly on the one of the flights offered by Zero Gravity Corp., a space tourism company.

Flying from Kennedy Space Center in Cape Canaveral, Fla., the jet creates the experience of microgravity in 25-second bursts of steep plunges over the Atlantic Ocean. Normally, the plane conducts 10 to 15 plunges for its passengers who pay $3,750 for the ride, although that fee has been waived for Hawking.

On Hawking's trip, the jet will make a single plunge. Other plunges will be made only after doctors and nurses who are accompanying the astrophysicist on the ride have made sure that he is enjoying it.

"We consider ... having him weightless for 25 seconds is a successful mission,'' said Peter Diamandis, the chairman and CEO of Zero Gravity. "If we do more than one, fantastic.''

Unable to use his hands, legs or voice, Hawking can only use his facial expressions using the muscles around his eyes, eye brows and mouth to communicate. Otherwise, he relies on a computer to talk for him in a synthesized voice. The computer is attached to his wheelchair and allows him to choose words on a computer screen via a sensor that detects motion in his cheek.

He won't have his wheelchair and talking computer on the jet with him, although his assistant will bring a lap top in case he wants to communicate beyond facial expressions.

"I hope it goes OK,'' Hawking said. "But there's always a chance things can go wrong.''