Soyuz 18

This article is about a 1975 spaceflight. For the previous aborted attempt, see Soyuz 18a. For the mission identified by NASA as ISS Soyuz 18, see Soyuz TMA-14.

Soyuz 18

Mission type	Docking with Salyut 4
Operator	Soviet space program
COSPAR ID	1975-044A
SATCAT no.	07818
Mission duration	62 days 23 hours 20 minutes 8 seconds
Orbits completed	993
Spacecraft properties
Spacecraft	Soyuz 7K-T No.7
Spacecraft type	Soyuz 7K-T
Manufacturer	NPO Energia
Launch mass	6570 kg
Landing mass	1200 kg
Crew
Crew size	2
Members	Pyotr Klimuk Vitaly Sevastyanov
Callsign	Кавказ (Kavkaz - "Caucasus")
Start of mission
Launch date	24 May 1975, 14:58:10 UTC
Rocket	Soyuz-U
Launch site	Baikonur, Site 1/5
End of mission
Landing date	26 July 1975, 14:18:18 UTC
Landing site	56 km at the east of Arkalyk, Kazakhstan 51°N 68°E
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	193.0 km
Apogee altitude	247.0 km
Inclination	51.6°
Period	88.6 minutes
Docking with Salyut 4
Docking date	26 May 1975
Undocking date	26 July 1975
Time docked	61 days
Vimpel Diamond patch Soyuz programme

Soyuz 18 (Russian: Союз 18, Union 18) was a 1975 Soviet crewed mission to Salyut 4, the second and final crew to man the space station. Pyotr Klimuk and Vitaly Sevastyanov set a new Soviet space endurance record of 63 days and the mark for most people in space simultaneously (seven) was tied during the mission.

Crew

Position	Cosmonaut
Commander	Pyotr Klimuk Second spaceflight
Flight Engineer	Vitaly Sevastyanov Second and last spaceflight

Backup crew

Position	Cosmonaut
Commander	Vladimir Kovalyonok
Flight Engineer	Yuri Ponomaryov

Mission parameters

• Mass: 6,570 kg (14,480 lb)
• Perigee: 193 km (120 mi)
• Apogee: 247 km (153 mi)
• Inclination: 51.6°
• Period: 88.6 minutes

Mission highlights

The Soyuz 18 crew were the back-up crew for the failed Soyuz 18a mission, carried out that mission's objectives, and continued the work of the previous Soyuz 17 crew. Klimuk and Sevastyanov were launched into space on 24 May 1975 and docked with Salyut 4 two days later. The crew quickly set to performing experiments and fixing or replacing equipment. A spectrometer was repaired, a gas analyzer was replaced, and a pumping condenser in the water regeneration system was switched with a hand pump.

On 29 and 30 May 1975, biological and medical experiments were performed and the Oasis garden was started. Studies of the stars, planets, Earth and its atmosphere were started on 2 and 3 June 1975. Some 2,000 photographs of the Earth and 600 of the Sun were reported taken.

More medical experiments were performed in June 1975, and attempts were made to grow plants, including onions. Experiments were carried out on insects, and experiments on varying the work schedule were carried out. Extensive medical experiments were carried out on 23 June 1975, as the crew surpassed the Soviet space endurance record of 29 days, set by Soyuz 17, the Salyut's previous crew. The all-time record was held then by the Skylab 4 crew at 84 days.

On 3 July 1975, it was announced that the mission would last beyond the upcoming Apollo-Soyuz Test Project (ASTP). To avoid any conflict of resources, the Soyuz 18 crew was controlled from the old Crimean Control Center, while the ASTP Soyuz 19 mission would be controlled from the Kaliningrad Control Center. The Crimean center had not been used since the Soyuz 12 flight. This was the first time the Soviets had to control two unrelated space missions.

The ASTP crews were launched 15 and 16 July 1975, and the Soyuz 18 crew communicated with the Soyuz 19 crew on two brief occasions. The total of seven people in space tied the record set by the Soyuz 6, Soyuz 7 and Soyuz 8 flights of 1969. Once the American ASTP crew landed 24 July 1975, the Soviets had a near six-year monopoly on crewed space flights until the launch of the first Space Shuttle, STS-1, on 12 April 1981.

The Salyut living conditions were starting to degrade by July 1975, with the environmental control system failing, windows fogged over and green mold growing on the station walls. The crew donned exercise suits and increased their exercise period to over two hours a day, and on 18 July 1975 began to prepare the station for uncrewed flight. The Soyuz craft was activated on 24 July 1975 and the crew returned to Earth two days later, on 26 July 1975. It landed at 56 km at the East of Arkalyk, Kazakhstan. The cosmonauts exited the capsule under their own power, but it was two days before Klimuk could take a 10-minute walk, and a week before he made a full recovery.

Soyuz-18 Rock in Antarctica is named after the mission.