He has spent two decades and nearly $20 million in a quest to fly to the upper reaches of the atmosphere with a helium balloon, just so he can jump back to earth again. Now, Michel Fournier says, he is ready at last.

Depending on the weather, Fournier, a 64-year-old retired French army officer, will attempt what he is calling Le Grand Saut (The Great Leap) on Sunday from the plains of northern Saskatchewan.

He intends to climb into the pressurized gondola of the 650-foot balloon, which resembles a giant jellyfish, and make a two-hour journey to 130,000 feet. At that altitude, almost 25 miles up, Fournier will see both the blackness of space and the curvature of the earth.

Then he plans to step out of the capsule, wearing only a special space suit and a parachute, and plunge in a mere 15 minutes, experiencing weightlessness along the way.