Professor Stephen Hawking will free himself from his wheelchair this week to experience being weightless.
The renowned theoretical physicist, almost totally paralysed with motor neuron disease, will float within a specially adapted passenger jet put into a steep dive to simulate zero gravity.
Prof Hawking's flight is courtesy of Zero Gravity Corporation, a space tourism and entertainment company based in Fort Lauderdale, Florida.
The flight is scheduled for 7.30pm, UK time tomorrow.
G-Force One, a modified Boeing 727, will follow a roller-coaster course of parabolic manoeuvres, starting with a steep climb to around 32,000 ft before plunging 8000 ft.
At the beginning of each descent, passengers experience short episodes of near or total weightlessness lasting about 25 seconds. Normally about 15 climbs and dives are carried out.
Floating around the padded aircraft cabin, it is the nearest thing to being on a space walk. When the plane pulls out after a dive, occupants feel a G-force almost twice normal gravity.
A team of medical assistants will be on hand to check on Prof Hawk-ing's condition.