Testing Mankind's Limits

U.S. Air Force aviation doctor, John Paul Stapp, tested the limits of human physiology both on the ground and in near-space. Not satisfied with the accepted belief that 18 G's -- or 18 times the pull of gravity -- could kill a person, he set out to prove humans could survive acceleration and deceleration at rapid speeds and from dizzying heights. "Space Men" premieres March 1 at 9/8c on PBS.