Jan. 21, 1960: Miss Sam launches

Today in the history of astronomy, a rhesus monkey tests the Mercury spacecraft.
By | Published: January 21, 2026

On Dec. 4, 1959, rhesus monkey Sam (named for the acronym for the Air Force School of Aviation Medicine) was launched on a Little Joe rocket attached to a Mercury spacecraft. The Little Joe rockets were used in test flights for the Mercury program, to ensure the Launch Escape System (LES) and recovery parachutes were functional before the first American astronauts ventured into space. And while the equipment was being tested, passenger animals like Sam were used to analyze possible effects of weightlessness, radiation, and other conditions of spaceflight on the human body.

One minute into Sam’s flight, the Mercury spacecraft separated from the rocket, and returned to Earth from an altitude of 51 miles, splashing down about 10 minutes later. Sam rode inside a cylinder within the spacecraft, and was recovered safely from the Atlantic Ocean. A little less than two months later, on Jan. 21, 1960, his mate, called Miss Sam, was rocketed to an altitude of 9 miles in a further test of the LES. She, too, was recovered safely. Both monkeys returned to their training colony in apparent good health and lived out their lives; although Miss Sam’s date of death wasn’t recorded, Sam lived until 1982.