Felix Baumgartner is attempting to break the skydiving record by jumping from the edge of the Earth's atmosphere, around 23 miles up.
His team has built a special balloon to send him up, a special chute to slow him down and a special suit to stop his blood from boiling in the low pressure at the top of the Earth's atmosphere.
Mr Baumgartner, who will break the speed of sound with in 30 seconds of jumping, said that "the biggest unknown so far is what happens the human body when it travels at supersonic speed".
Colonel Joe Kittinger, whose record Felix is trying to break, described his own experiences. He told the Today programme's Evan Davis that Mr Baumgartner "will be able to see almost 500 miles and overhead it's absolutely black above... It's a heck of a perch".
Get in touch with Today via
or text us on 84844.