Soyuz 34

Soyuz 34

Operator	Soviet space program
COSPAR ID	1979-049A
SATCAT no.	11387
Mission duration	73 days, 18 hours and 16 minutes
Orbits completed	~1,200
Spacecraft properties
Spacecraft type	Soyuz 7K-T
Manufacturer	NPO Energia
Launch mass	6,800 kg (15,000 lb)
Crew
Crew size	0 up 2 down
Landing	Vladimir Lyakhov Valery Ryumin
Start of mission
Launch date	June 6, 1979, 18:12:41 (1979-06-06UTC18:12:41Z) UTC
Rocket	Soyuz-U
Launch site	Baikonur 31/6
End of mission
Landing date	August 19, 1979, 12:29:26 (1979-08-19UTC12:29:27Z) UTC
Landing site	170 km (110 mi) SE of Dzhezkazgan
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Perigee altitude	199 km (124 mi)
Apogee altitude	271.5 km (168.7 mi)
Inclination	51.62 degrees
Period	88.91 minutes
Docking with Salyut 6
Docking port	Aft
Docking date	June 8, 1979, 20:02:06 UTC[1]
Undocking date	June 14, 1979[2]
Time docked	6 days
Redocking with Salyut 6
Redocking port	Front
Redocking date	June 14, 1979
Unredocking date	August 19, 1979, 12:29:26 UTC[1]
Time redocked	66 days
Soyuz programme ← Soyuz 33 Soyuz 35 →

Soyuz 34 (Russian: Союз 34, Union 34) was a 1979 Soviet uncrewed space flight to the Salyut 6 space station. It was sent to supply the resident crew a reliable return vehicle after the previous flight, Soyuz 33, suffered an engine failure.

Mission control decided to re-design the engine used on Soyuz craft as a result of the Soyuz 33 failure, and to return the Soyuz 32 craft which transported Vladimir Lyakhov and Valery Ryumin to the space station to Earth uncrewed as it had the same suspect engine as Soyuz 33. Soyuz 34 successfully returned the crew to earth 73 days after launching.

Position	Launching Crew Member	Landing Crew Member
Commander	None	Vladimir Lyakhov First spaceflight
Flight Engineer	None	Valery Ryumin Second spaceflight

• Mass: 6,800 kg (15,000 lb)
• Perigee: 199 km (124 mi)
• Apogee: 271.5 km (168.7 mi)
• Inclination: 51.62°
• Period: 88.91 minutes

Soyuz 34 had been intended to have been launched around 6 June 1979 with a two-man Hungarian/Soviet crew. That crew would have presumably returned in Soyuz 33 which had been planned to be docked at the Salyut 6 space station. Suspicions this was originally to be a Hungarian/Soviet flight were confirmed in 1980 when press releases for an upcoming joint mission were still dated June 1979.^[3]

However, the engine failure during Soyuz 33's flight in April necessitated a shuffling of planned missions. Because the engine used in that flight was the same model already docked at the space station on Soyuz 32 and the resident crew of Vladimir Lyakhov and Valery Ryumin needed a reliable craft to return to Earth in, it was decided that the engine needed to be modified and a fresh return vehicle sent to the station - vacant.^[4]

Soyuz 34 was launched uncrewed on 6 June, and docked at the aft port of the space station on 9 June. The flight itself was a test of the new engine and its success meant the crew had a reliable return craft. Since the craft was uncrewed, some biological samples for experiments were included on the flight.^[4]

Soyuz 32 was loaded with 130 kg of replaced instruments, processed materials, exposed film and other items with a total weight equal to that of the two cosmonauts. On 13 June, it undocked and returned to Earth uncrewed 295 km northwest of Dzhezkazgan. The craft was found to be in good condition.^[3] The next day, the crew redocked Soyuz 34 at the forward port to clear the aft port for Progress 7, a supply tanker.^[4]

On 19 August, the resident crew returned to earth in Soyuz 34, establishing a new space-endurance record of 175 days, surpassing the 139-day mission by the Soyuz 29 crew in 1978.^[3]

Years later, a similar scenario of crew return was required in 2022. As Soyuz MS-22 was unable to perform crew return due a coolant leak in external radiator, it returned uncrewed with cargo instead of crew like Soyuz 32, and Soyuz MS-23 was launched unmanned with cargo like Soyuz 34 as a replacement to return the crew.^[5][6]

• Soyuz MS-22
• Soyuz MS-23