Animals in Space

In early 1961, just a few months before Soviet cosmonaut Yuri Gagarin launched into orbit, NASA was using chimps to help iron out the kinks in its Mercury program.
Ralph Crane / Time Life Pictures / Getty

Chimp in Training
In early 1961, just a few months before Soviet cosmonaut Yuri Gagarin launched into orbit, NASA was using chimps to help iron out the kinks in its Mercury program. Approximately 20 of them were trained at Holloman Air Force Base in New Mexico on equipment simulating space flight, like the rocket sled, above.

Get the Latest Photos from Time.com
Get TIME photos and pictures of the week delivered directly to your inbox.