65 years ago today, NASA introduced the Mercury Seven, America’s first astronauts! All 7 men were military test pilots, because NASA felt they’d possess the right skills for space travel. Other selection criteria included that they be under 40 years old, less than 5’11, and in excellent physical shape. From a pool of 508, they whittled the number of candidates down to 36. The men were then subjected to all kinds of intense physical and psychological testing, including 2 hours in a chamber heated to 130 degrees and spending hours on treadmills and tilt tables. All of the Mercury Seven eventually flew in space and were on all of NASA’s human spaceflight programs in the 20th century. Learn more here.