Soviet Zond 5's Historic Circumlunar Flight with Tortoises Precedes Apollo 8
In 1968, the Soviet spacecraft Zond 5 became the first mission to carry living creatures, specifically two Central Asian steppe tortoises, around the Moon and back to Earth. Launched on September 15, 1968, Zond 5 passed approximately 1,950 kilometers above the lunar far side on September 18, before returning to Earth on September 21. The mission was a precursor to a potential crewed Soviet lunar mission and included a biological experiment with the tortoises, fruit flies, worms, and plants. The tortoises, which were the largest and most recognizable of the biological payload, survived the journey, although they lost about 10% of their body weight due to a pre-launch fasting experiment. The mission demonstrated the feasibility of a circumlunar flight, setting the stage for future human space exploration. 
