The Soviet Union launched the dog Laika into space in November 1957 and proved it was possible to maintain life in space for at least a limited amount of time. Further Soviet and U.S. flights with animals confirmed this. What scientists did not know was, would pilots be able to function reliably?
In addition to advanced flight training and teaching their pilots to withstand high gravitational forces, the Soviets emphasized fitness training for their cosmonaut candidates.
NASA used the U.S. Navy's centrifuge at Johnsville, Pennsylvania, to test astronauts' ability to withstand severe acceleration and deceleration forces. Here, Alan Shepard takes a spin in the centrifuge.
The U.S.S.R. launched two dogs, Belka and Strelka, into orbit in August 1960. This day-long mission was one of several test orbits of the Vostok hardware. The dogs survived and lived to produce litters of puppies.
NASA launched the chimpanzee Ham on a suborbital flight in January 1961. Shown here in his couch after his ocean recovery, Ham survived the flight in good shape and lived until 1983.