Belka and Strelka (11/15)

Belka and Strelka spent a day in space aboard Korabl-Sputnik 2  on August 19, 1960, before safely returning to Earth. They were accompanied by a grey rabbit, 42 mice, two rats, flies, and several plants and fungi. All passengers survived. They were the first Earth-born creatures to go into orbit and return alive.