No human had been to space. Animals including dogs and monkeys had already been sent up to test the biological effects of weightlessness. From a group of about 40 chimps, preparations began. The chosen chimp would be given training with positive and negative reinforcement to complete simple tasks of pushing buttons and pulling levers. No.65 would be part of Project Mercury. He was called No.65 in case he did not survive the flight. If the mission failed, bad publicity for NASA would follow the death of a “named” chimpanzee . After his safe return to Earth, he was renamed HAM, after the Holloman Air Force base where he received his training. His successful flight paved the way for America's first human astronaut Alan B. Shepard Jr.
Read about Ham's journey here.