John Glenn was not popular with the other astronauts. Glenn was the backup pilot for Shepard and Grissom on the first two manned Project Mercury flights, the sub-orbital missions Mercury-Redstone 3 and Mercury-Redstone 4. Glenn was selected for Mercury-Atlas 6, NASA's first manned orbital flight, with Carpenter as his backup. Putting a man in orbit would achieve one of Project Mercury's most important goals. Shepard and Grissom had named their spacecraft "Freedom 7" and "Liberty Bell 7". The numeral 7 had originally been the production number of Shepard's spacecraft, but had come to represent the Mercury 7. Glenn named his spacecraft, number
John Glenn younger than 40, possess a bachelor's degree or equivalent, and be or less. Only the height requirement was strictly enforced, owing to the size of the Project Mercury spacecraft. This was fortunate for Glenn, who barely met the requirements, as he was near the age cutoff and lacked a science-based degree. The 110 were then split into three groups, with the most promising in the first group. The first group of 35, which included Alan Shepard, assembled at the Pentagon on February 2, 1959. The Navy and Marine Corps officers were welcomed by the Chief of Naval Operations, Admiral Arleigh