Cosmonauts are the Russian counterparts to American astronauts. During the early years of the "space race" between the two superpowers, the United States and the Soviet Union, it was the Soviet Union who took the lead. Cosmonauts achieved the records for sending the first human into space, the first space walk, and the first woman in space, Valentina Tereshkova. Yuri Gagarin, the first man in space, was honored by the Soviet Union as a hero, and a cosmonaut training center was named after him.

The first cosmonauts underwent similar training, as well as scrutiny, that American astronauts endured. Tests were conducted on everything from stamina to eyesight. Each candidate was required to be in good physical and mental condition. Training itself was strenuous, including simulators for zero-g and spacecraft controls.

Just as many astronauts were selected from the military, most of the early cosmonauts were selected from the...