For more than 40 years, Stephen Hawking has studied the mysteries of the universe from his wheelchair. Last night, he broke free of his disability and indulged his passion for gravitational phenomena in a finely stage-managed operation 32,000 feet above the Atlantic.

“It was amazing,” he said after he returned from his experience of weightlessnes. “The zero-g bit was wonderful . . . I could have gone on and on. Space, here I come.”

Peter Diamandis, head of Zero-G, a company that gives the public the chance to experience space-like conditions for about £2,000, said that the professor told his carers after the first of eight zero-gravity plunges that he would like to perform a 180-degree “flip” with his body.

He had spelt out his request using an alphabetical board as his electronic voice synthesizer was removed to allow him to drift free of electrical wires. “He was doing gold-medal gymnastics in zero-g, it was incredible,” Mr Diamandis said.

When asked if he was enjoying himself, Professor Hawking’s “eyebrows went up and there was a big grin . . . he was grinning the entire time”, Mr Diamandis said.

He added: “Professor Hawking reached for the sky and he touched the heavens today.”

The astrophysicist, who in 1963 was given less than three years to live after doctors diagnosed motor neuron disease, floated in zero gravity onboard a nose-diving Boeing 727 known as “G-Force One”.

The aircraft managed to simulate zero-gravity through a series of rollercoaster-style manoeuvres, known as parabolas. These moves help passengers to achieve the weightlessness they would experience in space for up to 25 seconds at a time.

Professor Hawking, 65, who teaches mathematics at Cambridge University and whose books include the bestselling A Brief History of Time, was assisted by a team of three doctors throughout the 90-minute adventure. He was able to breathe unaided while the doctors monitored his vital signs using an oxygen sensor clipped to his earlobe, a blood pressure cuff around his arm and a heart monitor hooked up to his chest.

Professor Hawking, whose theories on the Universe have singled him out as one of the world’s brilliant thinkers, viewed the flight as the first step to completing his dream of space travel.

“I have been wheelchair-bound for almost four decades and the chance to float free in zero gravity will be wonderful,” he said, speaking through his computer-operated voice synthesizer, before boarding the flight from Kennedy Space Centre in Florida.

“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. I think the human race has no future if it doesn’t go into space,” he said.

The flight mimics the methods used to train Nasa astronauts — who refer to their own zero-gravity aircraft as the Vomit Comet, because of the regularity with which they lose their lunch to its stomach-churning manoeuvres.

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