After launching the Soviet’s Sputnik I in 1957 and the United States’ Explorer I in 1958, scientists on both sides began acquiring non-human subjects for space experimentation. Since the late 1940s, a variety of animals were used in US military flight experiments. During the Space Race, experimentation included testing the effects of the harsh conditions of space. After a stray Soviet dog, Laika, became the first animal to achieve Earth orbit in Sputnik II in 1957, the use of animals as test subjects greatly increased. This was particularly true for chimpanzees, who were often used to test the effects of gravity and high-speed motion. The chimps were tested in small metal capsules and controlled by electric shocks. Unfortunately, the chimpanzees were sometimes killed or severely injured during tests, though their involvement ensured human safety during actual space travel.
In 1961, the US test subject, Ham, became famous as the first chimpanzee in space. During his flight, technical difficulties occurred, forcing him to go higher and faster than anticipated. However, Ham splashed down safely in the Atlantic Ocean and even posed for pictures afterwards. Ham’s mission was an important precursor to Alan Shepard’s Freedom 7 launch later that year. Another famous chimpanzee, Enos, achieved Earth orbit in the same year, orbiting twice before successfully returning home. His flight paved the way for John Glenn’s successful orbit in 1962.