The Soyuz OIS (Orbital Research Station) would consist of a separately-launched orbital block 11F731 OB-VI and a transport Soyuz 7K-S.
Soyuz OB-VI The Soyuz OB-VI would be launched for 30-day missions in a 51.6° orbit at 250 x 270 km. Power was provided by
solar panels, and the payload included 700 to 1,000 kg of instrumentation. The total mass would be around 6,500 kg (14,300 lb).
Soyuz 7K-S The initial Soyuz 7K-S program was to consist of four uncrewed, followed by two crewed test flights, then two operational launches. Cosmonauts were assigned to the project in 1973. In 1975, the project was cancelled. At that time the
launch escape system for 7K-S was ready and was used for
Apollo-Soyuz Test Project flights. Three complete vehicles were launched as uncrewed test missions:
Soyuz 7K-ST The Soyuz 7K-ST transport project was develop in parallel to the military 7K-S and was redesigned for a crew of three, eventually becoming the
Soyuz-T used with the
Salyut space stations.
Specifications • Crew Size: 2 • Total Length: 7.5 m • Maximum Diameter: 2.7 m • Total Habitable Volume: 9.00 m3 • Total Mass: 6,800 kg • Primary Engine Thrust: 400 kgf • Main Engine Propellants:
N2O4/
UDMH • Main Engine Isp: 305 seconds • Electrical System: Solar panels ==Relation with other Soyuz versions==