Mission Type: Flyby
Launch Vehicle: 8K82K + Blok D upper stage (Proton-K no. 234-01 / Blok D no. 17)
Launch Site: Tyuratam (Baikonur Cosmodrome), USSR, NIIP-5 / launch site 81L
Spacecraft Mass: about 5,375 kg
Spacecraft Instruments: 1) biological payload; 2) radiation detectors; and 3) imaging system
References:
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi

National Space Science Data Center, http://nssdc.gsfc.nasa.gov/

Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.

Zond 5 was the first Soviet spacecraft to complete a successful circumlunar mission-after three failures.

During the flight to the Moon, the main stellar attitude-control sensor failed due to contamination of the sensor's optical surface. Controllers used less accurate backup sensors to perform two midcourse corrections. The spacecraft successfully circled around the far side of the Moon at a range of 1,950 kilometers on 18 September, taking high-resolution photos of the Moon and Earth.

On the return leg of the flight, a second attitude-control sensor failed and the spacecraft's three-axis stabilization platform switched off the guided reentry system. As a result, Zond 5 performed a direct ballistic reentry (instead of a guided one) and splashed down safely in the backup target area in the Indian Ocean at 32°38' south latitude and 65°33' east longitude, about 105 kilometers from the nearest Soviet tracking ship. Landing time was 16:08 UT on 21 September.