Hawking prepares for weightless 'bliss' [edited]

For almost four decades, the astrophysicist Stephen Hawking has studied black holes, exploding stars and the origins of the universe from the confines of his wheelchair.

Tonight, at around 7pm, the renowned Cambridge professor will experience the weightlessness of space at first hand on a zero gravity trip over the Atlantic.

The 90-minute adventure aboard a converted airliner nicknamed the vomit comet marks the achievement of a lifelong ambition for the cosmologist, who was once told by doctors not to bother finishing his PhD because of advancing motorn neurone disease.

"It will be wonderful," said Professor Hawking, whose best-selling A Brief History of Time popularised the theories of quantum gravity and enlightened the masses about many of the mysteries of the universe.

"For someone like me, whose muscles don't work very well, it will be bliss to be weightless."

The 65-year-old, who has spent most of his adult life in a wheelchair and communicates through a synthesised voicebox, is due to be looked after by a team of four doctors and two nurses on the flight from the space shuttle runway at Kennedy Space Centre.

They will attach an oxygen sensor to his earlobe, fix monitors on his arm and chest to check his blood pressure and heart rate during the ascent, and cushion his head with a custom-made restraint. He plans to communicate with them through nods and smiles.

However, unlike many of the other 2,500 commercial passengers who have already experienced weightlessness aboard the plane and vomited the first time it plunged sharply back towards Earth after a steep climb to 32,000ft, Prof Hawking was not expecting to need a sick bag.

"He's very game for it and was grinning from ear to ear when I explained how it would feel," said Peter Diamandis, the founder and chief executive of Zero-G, a Las Vegas company that has offered the adventure to would-be space tourists for $3,750 (£1,875) a ticket since 2004.

The zero gravity effect is produced by the Boeing 727 performing a series of up to 15 parabolas per flight, similar to the peaks and dips of a roller coaster.

Each nosedive, to around 24,000ft, produces 25 to 30 seconds of weightlessness before the plane levels out and climbs again. Passengers are able to float around inside the padded interior of the aircraft in exactly the same way that astronauts do in space.

"Having him weightless for 25 seconds will be a successful mission," Dr Diamandis said. He added that the medical team would evaluate Prof Hawking after the first parabola and see whether he wanted to try any more.

To counter the possible effects of motion sickness, the pilot will level out for a longer period than usual after each dip, giving resistance of 1.5 times the body weight instead of 1.8.

"It's truly an honour to have somebody of Prof Hawking's standing on our most significant zero gravity flight to date," Dr Diamandis added. "He is proving that disabled people, the elderly and children can experience the freedom and mobility of weightlessness, and be joyful.

"For people 1,000 years from now, people who might be living in private space colonies and travelling far beyond Earth, Professor Hawking is a true pioneer."

The flight will be much more than just a white-knuckle thrill for Prof Hawking, who has been described by the Nasa chief, Michael Griffin, as "one of the most imaginatively perceptive scientists of all time".

It is a major step towards his goal of a flight beyond the Earth's atmosphere as a guest of Sir Richard Branson's fledgling Virgin Galactic space tourism company before the end of the decade.

"I'm excited about flying in space some day, and this zero gravity flight is my first step," he said. "I want to encourage public interest in space."

Such exploration, he believes, is the key to securing mankind's future. "I think the human race has no future if it doesn't go into space," he warned.

"Life on Earth is at the ever-increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers we have not yet thought of."

Steve Kohler, the president of Space Florida, a Nasa partner which has sponsored Prof Hawking's flight, said he expected his adventure would encourage people who thought they were not suited to weightless flight to give it a try.

"I've yet to see anyone return from a zero gravity flight with anything other than a smile on their face," he added.