Most people assume the first hominid in orbit was a man. It was a chimpanzee purchased from a Miami rare bird farm. Enos replaced the original chimp, Ham, after Ham’s suborbital flight. NASA prepared him for 1,263 hours over three years. He learned to perform lever-pulling tasks in response to colored lights for banana pellet rewards and to avoid mild electrical shocks to his feet. His mission was an essential, final dress rehearsal before John Glenn’s flight. If Enos could work and survive in orbit, a human probably could.
At 10:08 AM Eastern Time, the Atlas rocket launched from Cape Canaveral. Enos was strapped into a custom couch inside a pressurized capsule. The planned three-orbit flight went awry. A faulty thruster caused the capsule to yaw, forcing the automatic system to fire correction rockets excessively, wasting fuel. The malfunctioning attitude control also altered the sequence of Enos’s psychomotor tasks. He kept performing, earning his sugar pellets, but the system administering the shocks began malfunctioning. Enos received shocks regardless of his correct lever pulls. He continued working. After two orbits, ground control aborted the mission due to the fuel and electrical issues. The capsule splashed down 200 miles south of Bermuda 75 minutes later. Enos was found calmly waiting in the spacecraft, having removed his own sensors.
He died of shigellosis, a bacterial dysentery, less than a year later. His flight is a footnote between Ham and Glenn. Its significance is technical, not symbolic. The malfunctions during his mission exposed critical flaws in the spacecraft’s systems, which were corrected before a human pilot flew. Enos proved a body could endure weightlessness and radiation. More importantly, his ordeal proved the machine was not yet ready. His confused, shocked perseverance in orbit provided the data needed to finish building a safe ship for a person.