Soyuz 35 (Russian: Союз 35, Union 35) was a 1980 Soviet manned space flight to the Salyut 6 Space Station. It was the 10th mission to and eighth successful docking at the orbiting facility. The Soyuz 35 crew were the fourth long-duration crew to man the space station.

Cosmonaut and Valery Ryumin spent 185 days in space, setting a new space endurance record. Ryumin had completed a previous mission only eight months before. They hosted four visiting crews, including the first Hungarian, Cuban and Vietmanese cosmonauts.

As long-duration crews now routinely swapped spacecraft with incoming crew, the Soyuz 35 craft was used to return the visiting Soyuz 36 crew to Earth, while the resident crew returned in Soyuz 37.

Soyuz T-2 (Russian: Союз T-2, Union T-2) was a 1980 Soviet manned space flight to the Slayut 6 Space Station. It was the 12th mission to and 10th successful docking at the orbiting facility. The Soyuz T-2 crew were the second to visit the long-duration Soyuz 35 resident crew.

Soyuz T-2 carried Yuri Malyshev and Vladimir Aksyonov into space. A mission lasting under four days, its primary purpose was to perform a manned test of the new Soyuz-T spacecraft.

The flight was originally scheduled for 5 June 1979, but was cancelled due to the Soyuz 33 failure. They successfully docked at the aft port the day after launching. The flight was the fifth Intercosmos flight whereby guest cosmonauts from Soviet allied nations would visit the space station, typically for about a week. The flight was only the second time a Soviet mission had a civilian commander.

Upon boarding, the visiting crew carried out Hungarian experiments, so many that the visiting crew sometimes only got three hours of sleep. One experiment was Pille, which measured radiation doses received by the crew with miniature thermoluminescent devices attached to their clothing and to the walls of the station. Another three experiments studied the formation of interferon in human cells under weightless conditions. Earth resources work using the on-board cameras were carried out, in coordination with ground crews, airplanes and helicopters.

Farkas was said by the Hungarian press to have adjusted far quicker than Kubasov to the weightless conditions.

The Soyuz craft was used to boost the station's orbit on 29 May, then Kubasov and Farkas swapped Soyuz craft with the long-duration crew, exchanging seat liners, pressure suits and personal items, before departing the station in Soyuz 35 on 3 June and landed 140 km southeast of Dzhezkazgan. The Soyuz 36 spacecraft was later used to return the crew of Soyuz 37 to earth.