Big Joe 1, the first Project Mercury spacecraft to cross the Karman Line (100 km) into space, and the first to ride an Atlas rocket, was launched on this day in 1959. The purpose of the flight was to test the capsule's heat shield, but it almost didn't come off, because the capsule almost didn't come off the rocket. Flight control had to fire the capsule's manoevring thrusters to yank it free of the rocket stage after the explosive bolts failed. Overall the Atlas didn't cover itself with glory, and it wasn't until 1962 that NASA dared put an astronaut atop one. The heat shield worked, though, and the capsule is now in the National Air and Space Museum.