An automated version of Soyuz, known as Progress-M, was developed to
carry propellant and cargo to the Salyut and Mir space stations and it will serve the same
purpose for the International Space Station (ISS). Although the Mir and ISS have their own
propulsion systems, generally it is the Progress vehicle which will perform periodic
reboosting maneuvers to maintain the Space Station orbital altitude. The Progress is
approximately the same size as the Soyuz but it has a slightly higher mass at launch of
approximately 7150 kg. The Progress spacecraft docks automatically to the space station
and there is also a backup remote control docking system. The Progress is composed of
three modules: Cargo Module, Refueling Module, and Instrument-Service Module.
The Progress cargo module is similar in construction to the Soyuz orbital module. The
cargo module carries pressurized cargo which the crew transfers into the station through
the docking hatch. After the cargo module is unloaded, trash, unwanted equipment, and
waste water can be loaded into the Progress for disposal when the spacecraft leaves the
Station.
In place of the Soyuz descent module, the Progress has a module containing propellant
tanks. The Progress is able to transfer propellant into the space station propulsion
system through fluid connectors in the docking ring. The propellant in the refueling
module can also be used by the thrusters on the Progress vehicle for controlling and
re-boosting the Station. The Progress M has four propellant tanks (two each for fuel and
oxidizer) and two water tanks. The Progress M1 will have eight propellant tanks and no
water tanks. In the Progress M1, water will be delivered in separate containers carried in
the cargo module.
The Progress instrument-service module is similar to the module on Soyuz but the
pressurized instrument section is twice as long and contains additional avionics
equipment. The larger instrument section carries avionics which would be contained in the
descent module in the case of the Soyuz.
A typical Progress mission is similar to a Soyuz mission. The spacecraft is launched by
the same launch vehicle inside a similar shroud, however there is no launch escape rocket
on the shroud since the spacecraft carries no crew. The Progress spends about two days
performing the rendezvous process and docks automatically to the Space Station.
Propellant is transferred to the Station tanks through connecting lines in the docking
ring The crew unloads cargo from the cargo module and can transfer water manually from the
Progress to the Station. When the Progress delivers air or oxygen, it is released directly
into the shared atmosphere of the Space Station and Progress vehicle. There are controls
in the cargo module for releasing air or oxygen and for transferring water.
While the Progress is docked to the Station it uses its propellant and thrusters to
perform Station reboost maneuvers. Trash is loaded into the cargo module when the Progress
has completed its mission and is ready to leave the Station. Progress vehicles normally
remain at the Station for two to three months.
After separation, the Progress spacecraft performs a deorbit maneuver and is destroyed
as it enters the atmosphere. Sometimes a small ballistic capsule is placed within the top
hatch of the cargo module and it is ejected during entry. The capsule is equipped with a
heatshield and parachute and is used to return small amounts of payload from the Station.
The Progress payload includes cargo in the pressurized cargo module and propellant in
the refueling module. There will usually be some excess propellant in the propulsion
system tanks in the ISM which can also be used by the Station.
The Progress M carries following cargo to a total ammount of 2350 kg
- Maximum Pressurized Cargo: 1800 kg
- Cargo Volume 6.6 m3
- Maximum Water 420 kg
- Maximum Air or Oxygen: 50 kg
- Maximum Refueling Module Propellant: 850 kg
- ISM Propellant Surplus available to Station: 250 kg
- Trash Disposal in Cargo Module: up to 1600 kg
- Waste Water 400 kg
The relative amounts of pressurized cargo, refueling propellant, air, and water will
vary within the constraints of the total payload limit. For example, if the maximum amount
of propellant is carried then the amount of pressurized cargo will be less than the
maximum amount.
Two units were modified to carry the VDU thruster modules to the space station Mir (Progress-M 14 and 38).
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