Thomas Kenneth "Ken" Mattingly II (born March 17, 1936) is a former NASA astronaut and a Rear Admiral in the United States Navy. He was one of the Apollo program astronauts, acting as support crew for Apollo 8 and Apollo 11. He also was the astronaut who helped with the development of the Apollo spacesuit and backpack. Mattingly should have been on Apollo 13, but he was removed from the crew a few days before the launch because he had been in contact with German measles. He was the Apollo Command Module pilot for Apollo 16 (April 16-27, 1972), which meant he stayed in orbit around the Moon while John Young and Charles Duke landed on the surface. During this time he performed 26 scientific experiments. He spent 3 days, 9 hours and 28 minutes by himself, the longest solo US space flight. On the return from the Moon, Mattingly completed a 1 hour, 13 minute, spacewalk.