Zond 5, a formal member of the Soviet Zond program and unmanned version of Soyuz 7K-L1 manned moon-flyby spacecraft, was launched by a Proton-K carrier rocket with a Blok D upper stage to conduct scientific studies during a lunar flyby and to return to Earth.
Zond-5 became the first spacecraft to circle the Moon and return to land on Earth. On September 18, 1968, the spacecraft flew around the Moon. The closest distance was 1,950 km. High quality photographs of the Earth were taken at a distance of 90,000 km. A biological payload of two Russian tortoises, wine flies, meal worms, plants, seeds, bacteria, and other living matter was included in the flight.
September 22, 1968, the reentry capsule entered the Earth’s atmosphere but could not perform a skip reentry due to failure of the guidance system. The capsule splashed down in the Indian Ocean and was successfully recovered by the USSR recovery vessels Borovichy and Vasiliy Golovin. The USS McMorris was shadowing Soviet ships, collecting intelligence information.
The biological payload was intact, proving that it was possible to survive a lunar flyby and safely return to Earth. It was announced that the tortoises had lost about 10% of their body weight but remained active and showed no loss of appetite. This spacecraft was planned as a precursor to a manned lunar spacecraft. The Zond 5 return capsule is on display at the RKK Energiya museum, in Russia.