Soyuz 23

Soyuz 23

Commemoration stamp of Vyacheslav Zudov and Valery Rozhdestvensky
Operator	Soviet space program
COSPAR ID	1976-100A
SATCAT no.	09477
Mission duration	2 days 6 minutes 35 seconds
Orbits completed	32
Spacecraft properties
Spacecraft	Soyuz 7K-T No.10
Spacecraft type	Soyuz 7K-T/A9
Manufacturer	NPO Energia
Launch mass	6750 kg [1]
Landing mass	1200 kg
Crew
Crew size	2
Members	Vyacheslav Zudov Valery Rozhdestvensky
Callsign	Радон (Radon - "Radon")
Start of mission
Launch date	14 October 1976, 17:39:18 UTC
Rocket	Soyuz
Launch site	Baikonur, Site 1/5[2]
End of mission
Landing date	16 October 1976, 17:45:53 UTC
Landing site	Lake Tengiz, Kazakhstan
Orbital parameters
Reference system	Geocentric orbit[3]
Regime	Low Earth orbit
Perigee altitude	243.0 km
Apogee altitude	275.0 km
Inclination	51.6°
Period	89.5 minutes
Vimpel Diamond patch Soyuz programme ← Soyuz 22 Soyuz 24 →

Soyuz 23 (Russian: Союз 23, Union 23) was an October, 1976, Soviet crewed space flight, the second to the Salyut 5 space station. Cosmonauts Vyacheslav Zudov and Valery Rozhdestvensky arrived at the station, but an equipment malfunction did not allow docking and the mission had to be aborted.^[4]

The crew returned to Earth, but landed on partially frozen Lake Tengiz, the first crewed splashdown in the Soviet space program. While there was no concern about any immediate threat to the crew, the capsule sank under the surface of the frozen lake, and recovery took nine hours owing to fog and other adverse conditions. The landing marked the only example of an unintentional splashdown of a crewed spacecraft to date.