Status: Study 1992. Gross mass: 102,000 kg (224,000 lb).
The heart of the facility (the Laboratory Compartment), where the materials processing equipment was installed, was based on the main core cylinder of the Proton launch vehicle's first stage. Above it was a TKS-derived module of the Kristal or Bioteknologiya class.
In support of the first Energia mission in 1987, the Salyut Design Bureau constructed a 100-ton class spacecraft called Polyus. Although the vehicle never reached orbit due to an attitude control problem, its designers expanded upon the original concept to propose a heavy Space Processing Module (SPM), also known as the Engineering Production Module (TMP). With a 102 metric ton launch mass, the SPM possesses an on-station (350-400 km, 51.5 degree inclination) mass of 88 tons. The Salyut engineers adopted well known hardware to create the SPM. In orbit SPM would be approximately 35 m long with a main diameter of just over 4 m.
In addition to the two sizable solar arrays extending from the Instrument-Cargo Compartment, the SPM had two very large arrays attached to the Laboratory Compartment with a total span of 60.4 m. Together, they would produce more than 60 kW for a mission exceeding five years. A total payload mass of up to 25 metric tons was possible with microgravity conditions of 10^-5 to 10^-6 g.
Expanding upon the idea of multiple return capsules proposed for the Bioteknologiya Space Vehicle, the SPM designers included a similar capability using 361 kg ballistic capsules with a payload mass of 141 kg and a payload volume of 92.5 liters. Robotics were used to remove a ballistic capsule from storage, load it, and then transfer it to a small airlock for ejection. This operation cycle would occur every 1-3 months.
Nine types of processing units were proposed for the SPM for a total of 45 individual installations with a total annual production capacity of more than one metric ton per year. A novel element of the SPM program was the option for man-tended operations. Docking ports at both the aft and forward end of the SPM would be compatible with a Soyuz TM spacecraft or the proposed MAKS spaceplane. The latter could be launched either by the Energia- M launch vehicle or from an air-based platform like the An-225. A maintenance or resupply crew could spend up to 10 days on the SPM unloading supply ships and repairing equipment. Unmanned resupply missions using Progress M or heavy Kosmos spacecraft were also envisioned. The advent of MAKS would also increase the opportunities (and therefore mass) for returning processed materials to Earth.
Complete design of the SPM would require two years, followed by four years of building and testing the flight module before launch. However, with the demise of the Energia and Energia-M programs and Russia's participation in the International Space Station, the SPM concept was dropped.