CAPE CANAVERAL, Florida: It might not seem like a brilliant idea, allowing a frail 65-year-old paralysed man to float free from gravity aboard a rising and plunging roller-coaster stunt flight.

But who is to argue with Stephen Hawking?

The celebrated British astrophysicist and black-hole theorist, author of A Brief History of Time, paralysed by motor neuron disease and communicating largely through eye twitches, has long wanted to visit space. Human survival depends on getting there, he says. An event here on Thursday was described as his first improbable step.

Dressed in dark blue flight suits, Professor Hawking and an entourage of carers boarded a Boeing 727 that roared out over the ocean and carved huge parabolic arcs in the sky, creating for passengers the floating zero-gravity effect of being in space.

While levitating, Professor Hawking, who has been in a wheelchair for nearly four decades, was spun twice - pirouetting like a "gold medal gymnast", a crew member said.

When each of the 25-second spells of zero gravity ended - as the plane headed to the bottom of each arc - assistants ensured that the celebrated physicist's body was lowered to a mattress on the plane's floor as gravity kicked back in. "It was amazing … I could have gone on and on," Professor Hawking said afterwards. "Space, here I come."

This flight was just his first step towards space. He hopes to take a greater leap into the heavens in 2009 on a space plane being developed by Richard Branson's company Virgin Galactic.

Before taking off he said life on Earth was "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. The human race has no future if it doesn't go into space. I therefore want to encourage public interest in space."

The Washington Post