Soyuz 32 launched Vladimir Lyakhov and Valeri Ryumin to Salyut 6 for the station's third resident expedition. After Soyuz 33 suffered a main-engine failure, Soyuz 32's similar engine was treated as suspect and the spacecraft returned uncrewed with experiment results. The uncrewed replacement Soyuz 34 delivered a modified engine and later returned Lyakhov and Ryumin after their record 175-day mission.