Michel Fournier aims for the Stratosphere

Somewhere high in the skies above Saskatchewan, Canada this week, a retired French army parachutist will jump from a height of 40,000 metres in a freefall he hopes will propel him faster than the speed of sound. If 58-year-old Michel Fournier is successful, his stunt will shatter four world records: the highest, fastest and longest freefall jump, and the highest balloon ascent.

Mr. Fournier and his team, who have dubbed this death-defying exercise Le Grand Saut or The Big Jump, were planning to take off in a massive helium balloon yesterday, but called off the jump because of high winds.

"The team is ready for this and will every day now be checking the weather until conditions are just right," said Diane de Robiano, spokeswoman for the project.

If the wind abates, the jump may take place in the next 24 hours, or possibly later in the week, she said. The exact location is being kept secret.

This experiment into how the human body responds to breaking the sound barrier is to be conducted by freefalling from a height where the earth's atmosphere meets space, a distance the project's Web site depicts as 4 1/2 Mount Everests stacked on top of each other.

The bizarre international venture has consumed the energies of more than two dozen scientists, physicians and technologists for more than a decade and has cost about US$3.4-million so far.

For Mr. Fournier, who has embarked on a relentless personal training regime that has included more than 8,000 jumps and periods of meditation, the leap would be the realization of his life's ambition.

He sold most of his personal assets and spent several years lining up international funding for the venture, which began as an unusual assignment when he was still a colonel in the French military.

"What attracts me most is the extreme challenge," Mr. Fournier said in a press conference earlier this summer.

The last attempt to break the highest freefall record proved to be fatal. In 1965, Nick Piantanida, a New Jersey truck driver, encountered equipment failure when his face mask blew out and the lack of oxygen caused such severe brain damage that he went into a four-month coma and died.

The current record for longest freefall was set in 1960 by Joseph Kittinger, a U.S. army captain, who dropped 25,820 metres from a balloon and reached a maximum speed of 1,006 km/h, slightly faster than the speed of sound. He fell for four minutes and 37 seconds before his parachute opened.

Mr. Fournier hopes to reach a maximum speed of 1,600 km/h, about 1 1/2 the speed of sound. His freefall is predicted to last about six minutes and 25 seconds.

The team involved in Le Grand Saut is relying on a wide range of state-of-the-art technology: a specially manufactured, remote-controlled balloon; and an air-tight and ultra-low temperature space suit designed to withstand temperatures as low as minus 100C for as long as 10 minutes.

The aim of the project, according to its Web site, is to simulate a full-scale rescue of a team of astronauts after reaching a critical high altitude.

"Studies of the new questions posed by this world premiere event, such as the issue of how to protect the skydiver from the bang of breaking the sound barrier, have mobilized hitherto unknown scientific techniques," the organizers boast.

What seems to be most worrisome for the team is the prospect of Mr. Fournier going into a spin at the beginning of his jump, which would make it virtually impossible to stop the rotation "because of the density of air at this altitude," said Henry Marotte, of the French Aerospace Medical Laboratory.

"That is the most worrying scenario from the medical perspective," he added.