By the zero hour...

Fournier will already have been breathing pure oxygen for two hours to help his body adapt. The balloon will then rise, taking more than two hours to reach its apex before he steps out to pierce the sky in temperatures plunging to minus 65 C and in pressures that, without a special suit, would quickly bring his blood to a boil.

He'll be tracked with global positioning trackers, radar, a helicopter and a Learjet. He expects to land within a 40-kilometre radius south of North Battleford.

If he lands unconscious, his team will have 15 minutes to get to him before his air runs out.

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