Washington: In December, buttressed by his conviction and advances in homemade rocketry, "Mad" Mike Hughes flipped on a camera and fantasised about the moment when he shows mankind that it lives on a verdant disk.

The plan was simple: fire into the sky on a steam-powered rocket and trigger a balloon to carry him to the Karman line, the 62-mile-high barrier that separates terrestrial from the extraterrestrial, filming the entire way. "For three hours, the world stops," Hughes said during a live stream.

Hughes, a self-styled daredevil, flat-Earth theorist and limousine stuntman, died on Saturday when his jury-rigged contraption propelled him on a column of steam, spiralled through the air and cratered into the sagebrush outside Barstow, California. He was 64.

"It was unsuccessful, and he passed away," longtime collaborator Waldo Stakes told the Associated Press, declining to comment further.