Space Station Assembly

Elements: Russian Progress

The Progress resupply vehicle is an automated, unpiloted version of the
Soyuz spacecraft that is used to bring supplies and fuel to the
International Space Station. The Progress also has the ability to raise
the station's altitude and control the orientation of the station using
the vehicle's thrusters. 

Both the Progress M and M1 versions have a pressurized Cargo Module to
carry supplies, a Refueling Module that holds fuel tanks containing
propellant and pressurized gases, and an Instrumentation/Propulsion
Module where the Progress systems equipment and thrusters are located.

The Progress spacecraft is launched to the space station from the
Baikonur Cosmodrome in Kazakhstan aboard a Soyuz rocket. It normally
docks to the end of the station's Zvezda Service Module, but it can also
dock to the bottom of the Pirs Docking Compartment.

Cargo Module

The Progress Cargo Module -- which is similar in construction to the
Soyuz Orbital Module -- can carry up to 1,700 kilograms (3,748 pounds) of
supplies to the space station in a pressurized volume of about 6 cubic
meters (212 cubic feet). Once the Progress docks with the space station,
the crew enters the Cargo Module through the docking hatch. After the
cargo is removed and before the Progress undocks, the crew refills it
with trash, unneeded equipment and wastewater, which will burn up with
the spacecraft when it re-enters the Earth's atmosphere. The Cargo Module
can hold 1,000 to 1,700 kilograms (2,205 to 3,748 pounds) of trash.

Progress Spacecraft Payload Capabilities 
Category Progress M Progress M1 
Total payload limit 2,550 kilograms
(5,622 pounds) 2,400 kilograms
(5,291 pounds) 
Maximum pressurized cargo 1,700 kilograms
(3,748 pounds) 1,700 kilograms
(3,748 pounds) 
Maximum water 420 kilograms
(926 pounds) In Cargo Module 
Maximum air or oxygen 50 kilograms
(110 pounds) 40 kilograms
(89 pounds) 
Maximum Refueling Module propellant 870 kilograms
(1,918 pounds) 1,740 kilograms
(3,836 pounds) 
Propellant surplus available to ISS 250 kilograms
(551 pounds) 185 - 250 kilograms
(408 - 551 pounds) 
Trash disposal in Cargo Module 1,000 - 1,600 kilograms
(2,205 - 3,527 pounds) 1,000 - 1,600 kilograms
(2,205 - 3,527 pounds) 
Maximum wastewater disposal 400 kilograms
(882 pounds) 420
(926 pounds) 
Cargo volume about 6 cubic meters
(212 cubic feet) about 6 cubic meters
(212 cubic feet) 


Refueling Module

In place of the Soyuz Descent Module, the Progress has a Refueling
Module. The Progress M1 Refueling Module has eight propellant tanks that
can hold up to 1,740 kilograms (3,836 pounds) of fuel, depending on how
much weight is carried in the Cargo Module. Four of the tanks contain
fuel, while the other four contain the fuel's oxidizer. The Progress M
has four tanks -- two for fuel and two for oxidizer -- and two water
tanks. The M1 has no water tanks.

The contents of the fuel and oxidizer tanks can be transferred to the
space station's own propulsion system through fluid connectors in the
docking ring. This propellant can also be used by the Progress' thrusters
to boost the station altitude or to change its orientation, or attitude,
in space. 

Instrumentation/Propulsion Module

This module contains the electronic equipment, or avionics, for the
Progress' systems and sensors. It is similar in design to the Soyuz
Instrumentation/Propulsion Module. Any fuel in this module that is not
used to get the Progress to the station or for undocking and deorbit can
be used to boost the altitude of the space station. Surplus fuel amounts
can vary from 185 to 250 kilograms (408 to 551 pounds).

Rendezvous, Docking and Undocking

The Progress normally takes two days to reach the space station. The
rendezvous and docking are both automated, although once the spacecraft
is within 150 meters (492 feet) of the station, the Russian Mission
Control Center just outside Moscow and the station crew monitor the
approach and docking.

The Progress uses an automated, radar-based system called Kurs to dock to
the station. The active portion of the Kurs is on the Progress and the
passive equipment in on the station. The station crew can also dock the
Progress using the TORU system, a backup remote control docking system in
the station's Zvezda Service Module. 

Once the Progress is filled with trash, usually a day before the launch
of the next Progress vehicle, the station crew closes the hatches and
initiates the undocking process. Once the Progress has undocked, the
vehicle's thrusters are fired to maneuver it into an orbit that will send
it into the Earth's atmosphere, where it will burn up on re-entry over
the Pacific Ocean.