37K-Mir Credit - © Mark Wade

Development of a new kind of Soviet space station module, designated 37K, was authorized on 17 September 1979. The basic 37K design consisted of a 4.2 m diameter pressurized cylinder with a docking port at the forward end. It was not equipped with its own propulsion system. The 37KS modules for Mir were cancelled in 1983 in favor of KB Salyut designs derived from the Chelomei TKS spacecraft.

Development of a new kind of Soviet space station module, designated 37K, was authorized on 17 September 1979. The basic 37K design consisted of a 4.2 m diameter pressurized cylinder with a docking port at the forward end. It was not equipped with its own propulsion system. The original authorization was for a total of eight 37K's of two configurations: 37KS for use as space station modules for Mir, and 37KB for use with the Buran space shuttle. Design and fabrication reached an advanced phase when it was decided that the separate tug concept resulted in too low a net scientific payload (3 metric tons). Integrating the tug with the module was expected to increase this to 5 metric tons and provide some reserve engine capability at Mir and additional pressurized volume. Accordingly the 37KS modules for Mir were cancelled in 1983. Competitive designs for integrated space station modules were submitted by KB Salyut and NPO Energia. The KB Salyut 77K modules were derived from the cancelled TKS manned ferry. The competing proposal from NPO Energia combined the 37KS module with the engine unit of Mir. In June 1984 the KB Salyut design was selected.

Maximum Diameter: 4.15 m (13.61 ft). Span: 4.20 m (13.70 ft). Mass: 20,000 kg (44,000 lb). Payload: 5,000 kg (11,000 lb). Main Engine: KRD-79. Main Engine Propellants: N2O4/UDMH. Main Engine Isp: 305 sec.

• 1979 September 17 - 37K space station module authorised -
  The basic 37K design consisted of a 4.2 m diameter pressurised cylinder with a docking port at the forward end. It was not equipped with its own propulsion system. The original authorisation was for a total of eight 37K's of various configurations. Of these, only the 37K-E (Kvant module of Mir) and the 37KS (instrumentation module in Buran) would fly.