By IAN SPARKS

Last updated at 18:27 13 August 2007

He will leap head-first from a weather balloon 25 miles above Earth and plummet at more than 1,000mph with only a parachute for company.

He will face external temperatures of minus 100c while inside his carbon-fibre suit it will be a stifling 65c - almost 150 fahrenheit.

And most amazing of all, Michel Fournier is actually looking forward to it.

The daredevil Frenchman, a greyhaired 63-year-old former paratrooper, aims to become the first person to break the sound barrier in free-fall.

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As he plunges through the stratosphere at supersonic speed, he also hopes to break three more world records - for the longest sky dive, the highest parachute jump and the highest altitude achieved by a human in a balloon.

Despite the intense cold outside, his £35,000 suit will heat up inside when it meets air resistance. His crash helmet will have its own air supply and reinforced ear pads to protect him from the sonic boom as he breaks through the Mach 1 sound barrier.

Fournier was one of three candidates selected in the 1980s to take part in a

military endurance test to see whether a parachutist could descend from 125,000ft - almost 24 miles.

The project was shelved in 1988 - but he decided to go it alone. He hopes to make the jump over the Great Plains of Saskatchewan in Canada some time next month, weather permitting.

"I would be lying if I said I wasn't afraid, but I am also very excited," he said."It really is a leap into the unknown."

After leaping from the balloon, Fournier believes he will break the 760mph sound barrier within 37 seconds.

The lack of friction due to the thinness of the air will mean he can attain a much higher terminal velocity, and his team of scientists estimate he will reach the top speed of 1,113mph before he is slowed down by greater air resistance.

His parachute will not open until six minutes, 25 seconds after jumping and he will finally reach the Earth after around eight and a half minutes.

The record for highest leap was set in 1960 by a U.S. Air Force test pilot, at just under 20 miles.