Expansion for Mir-1.5(Polyus)

this craft is docking hub for expansion

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 various configurations.

Four 37KS modules for Mir-1.5. These would also be launched by Proton and delivered and docked to the station by a new lighter weight FGO tug.
One experimental 37KE. This would be launched by a Proton booster together with a surplus FGB module (from the cancelled Chelomei TKS manned ferry). The FGB would serve as a tug to deliver and dock the 37KE to the front port of the Salyut 7 space station.
Three 37KB modules. These would be carried in the payload bay of the Buran space shuttle. They could remain attached to the bay or (modified to the 37KBI configuration) docked to the Mir or Mir-2 space stations using the Buran manipulator arm.
Production of the four 37KS modules was approved following review of the draft projects on 11 February 1981. The four modules would be placed into orbit by a Proton launch vehicle. The FGO tug section, connected to the 37KS module by a light lattice structure, would rendezvous with the Mir station and dock the module to one of the radial ports of the Mir station. It would then separate and deorbit itself into the earth's atmosphere. Each of the four modules had a different mission:

37KD - this module was equipped with an airlock and large hatch at the aft end to allow cosmonauts to conduct spacewalks from Mir.

You can dock SPK to it

37KT - the technological module was to be equipped with materials processing experiments and was equipped with a docking port for the Buran space shuttle.

37KP - this applications module was to be equipped with earth resources and military reconnaissance sensors.

37KG - this cargo module would deliver experiments to Mir too heavy for the Progress resupply ship.