The unique gondola will have an open roof for take-off but a canopy to protect its pilot from high-altitude winds and frostbite during the crossing.

If something goes wrong, Mr Trappe will change out of his UV protection suit into a cold water suit, pop enough balloons to bring the gondola close to the water, and attempt to land in the ocean.

Mr Trappe will float at between 18,000ft and 25,000ft, beating his previous world altitude record of 21,600ft. Previously the furthest distance he had flown uninterrupted was a world record 230 miles. To achieve the crossing, he must fly ten times that.