Zond 7 was the Soviet Unions first successful circumlunar mission.
After a spate of partial successes and catastrophic failures, Zond 7 was the first fully successful Soviet circumlunar mission. The spacecraft was the last 7K-L1 vehicle manufactured explicitly for robotic flight -- later models were equipped for crews.
Like its predecessors, Zond 7 carried a set of biological specimens, including four male steppe tortoises that were part of a group of 30 selected for the experiment.
After a midcourse correction on Aug. 8, 1969, at a distance of 155,343 miles (250,000 kilometers) from Earth, the spacecraft successfully circled the far side of the Moon two days later at a range of 746 miles (1,200 kilometers). Zond 7 performed color imaging sessions on Aug. 8, 1969 (of Earth) and Aug. 11, 1969 (two sessions of both Earth and the Moon).
The only major malfunction during the mission was the non-deployment of the main parabolic antenna (due to a problem in the securing cables), but this did not prevent a fulfillment of all the primary goals of the mission.
Zond 7 successfully carried out a guided reentry into Earth’s atmosphere and landed without problem south of Kustanay in Kazakhstan about 31 miles (50 kilometers) from the intended landing point after a 6-day, 18-hour, 25-minute flight.
Zond 7 (and Zond 8) carried on board a full-size human mannequin known as FM-2 to help study the effects of radiation and gravitational loads on various parts of the body during lunar-distance flights.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.