The U.S. Air Force test pilot reached a speed of Mach 6.72 (7,274 km/h or 4,520 mph) at the controls of his X-15 rocket plane.

On his wrist was a GMT-Master. Two weeks later, he flew the programme’s 190th flight, taking the X-15 to an altitude of above 80 kilometres (50 miles), which officially qualified him as an astronaut.