After the launch of Sputnik, the Russian space program focused on the moon as their next destination. The Luna series of spacecraft first tested the feasibility and logistics of Earth-to-moon travel and began explorations of the lunar surface — Luna 1 flew by, Luna 2 crash-landed on the surface, and Luna 3 photographed the dark side. The Zond program would expand on those findings.

On this day, September 15, in 1968 the unmanned Zond 5 (Zond just means “probe”) launched to the moon. Unlike the previous Luna missions, this one would be round-trip: the Zond swung around the moon and headed back to Earth.

On board the Zond 5 for the six-day trip were turtles, wine flies, meal worms, plants, seeds, bacteria, and other living matter. Both the turtles survived the trip: a little lighter, having lost 10% of their weight, but none the worse for wear.