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Mir Space Station - Progress: Detailed Description

The following notable features and detailed description of the Progress supply vehicle are excerpted from David Portree's Mir Hardware Heritage, available on this Web site in PDF format.

Progress Notable Features

• Launched on a Soyuz rocket under the same type of shroud as the Soyuz Ferry, but with no escape systems.
• Always docked with the aft port of its station target.
• Soyuz descent module replaced by tanker compartment, an assemblage of tanks in an unpressurized conical housing. The pressurized orbital module carried dry cargo. The crew could enter the orbital module to unload dry cargo, but had no access to the tanker compartment.
• No part of Progress was designed to be recovered. At the conclusion of its space station resupply mission, a Progress freighter was intentionally deorbited over the Pacific Ocean, where any pieces which survived incineration could fall harmlessly.

Progress Detailed Description

Spacecraft designer Konstantin Feoktistov published a brochure in 1980 in Moscow in which he described Progress in some detail. A summary is given below.

Feoktistov stated that Progress constituted an alternative to building reusable ("multiple use") logistics vehicles. A reusable vehicle, he asserted, would be 1.5 to 2 times heavier empty than the equivalent expendable logistics craft. This would call for a booster nearly as large as the three-stage Proton rocket used to launch Salyut. "If we are talking about an economically effective earth-orbit-earth transport system," Feoktistov continued, "then it appears expedient to build a fully multiple use complex, not only the spaceship, but also the booster rocket." This would take too much time; therefore, "when designing the Progress spacecraft the decision was made to make it single-use and to utilize the . . . Soyuz rocket to insert it [into orbit]."

The Progress orbital module ("cargo bay") was two hemispheres welded together through the intermediary of a short cylindrical section (very similar to the Soyuz orbital module). The forward hemisphere contained the docking unit and the port connecting the orbital module to the space station. Unlike Soyuz, Progress had no hatch in the aft hemisphere. The orbital module contained a supporting framework to which large equipment (such as air regenerators) was attached. Small items were packed in bins.

The probe and drogue docking unit used on Progress resembled the Soyuz unit. The chief difference was provision of two ducted mating connectors (one each for UDMH fuel and N 2 O 4 oxidizer) in the Progress docking collar for propellant transfer to corresponding connectors in the station collar. Three television cameras were carried near the docking unit.

The tanker compartment carried two tanks each of UDMH and N 2 0 4 . Feoktistov stressed that these propellants were "chemically aggressive and poisonous to man." To avoid spillage into the pressurized volumes of the station or the supply ship, fuel lines from the unpressurized tanker compartment ran along the exterior of the Progress orbital module, through the ducts in the docking collar, then into the unpressurized section containing the main propulsion system, which was located around the intermediate compartment at the aft end of the space station. The tanker compartment also carried tanks filled with nitrogen to serve as pressurant for the fuel system and to purge it of residual propellants. This prevented propellants from spilling on the docking apparatus and being accidentally introduced into the station.

Control equipment normally located in the Soyuz orbital and descent modules was placed in the service module of the Progress spacecraft. The service module also carried equipment for controlling propellant transfer. Progress had mounted to its service module two infrared local vertical sensors (horizon sensors) and two ion sensors for its guidance system. Soyuz, by contrast, had one ion sensor and one infrared horizon sensor. Redundancy was provided because Progress was a wholly automated craft. The Progress service module was longer than the Soyuz module because of the extra equipment it carried.

Related Links:
Mir Hardware Heritage
Spacecraft
Progress Supply Vehicle

Space Shuttle Orbiter | Mir Space Station

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