Gordo

Gordo, a squirrel monkey, was catapulted 600 miles high in a Jupiter rocket, also on December 13, 1958, one year after the Soviets launched Laika. Gordo's capsule was never found in the Atlantic Ocean. He died on splashdown when a flotation mechanism failed, but Navy doctors said signals on his respiration and heartbeat proved humans could withstand a similar trip.