Roach compares space exploration with extreme sports. At Perris SkyVenture in California, a skydiving training facility with an indoor vertical wind tunnel, professional BASE jumper and skydiver Felix Baumgartner trained for an upcoming mission to test a pressurized escape suit. Since the 1986 Challenger explosion, scientists have been interested in developing technology that allows for an emergency escape. The energy drink company Red Bull and the David Clark Company, the manufacturer of NASA’s spacesuits, sponsored Baumgartner’s mission. His 2012 jump, in which he free-fell from a helium balloon roughly 24 miles up in the sky, broke four records.

Falling from high altitudes comes with the risk of losing control and spinning. The lack of air resistance in a low-gravity environment makes it difficult to control body movements, and centrifugal speeds can be strong enough to detach the brain from the spinal cord. Equally dangerous are hypoxia—a lack of oxygen—and windblasts so strong they could damage organs and cause a person to vibrate to death.

The medical director for the Red Bull Stratos Mission is Jon Clark, a flight surgeon for NASA whom Roach met at the HMP on Devon Island. Clark was one of the investigators of the Space Shuttle Columbia disaster.