Progress spacecraft

The Progress is an expendable unmanned freighter spacecraft; it was derived from the Soyuz spacecraft, and is launched with the Soyuz launch vehicle. It is currently used to supply the International Space Station, supplementing what the two manned Soyuz flights per year can carry. There are three to four flights per year. Each spacecraft remains docked until shortly before the new one arrives, is filled with waste, disconnected, deorbited, and destroyed in the atmosphere.

It has carried fuel and other supplies to all the space stations since Salyut 6. The idea for the Progress came from the realisation that in order for long duration space missions to be possible, there would have to be constant source of supplies. It had been determined that a cosmonaut needed 30 kg of consumables a day; this equates to 5.4 tonnes over a 6 month stay. It was impossible to launch all this along with the station, or to bring up new supplies in the small space available in the Soyuz.

Progress is of much the same size and shape as Soyuz. It consists of three modules:

• A pressurised forward module. This contained the supplies for the crew such as food, scientific equipment, clothes, prepackaged and fresh food, and letters from home. The docking drogue is similar to that of the Soyuz but featured ducting for the UDMH fuel and N₂O₂ oxidiser.
• A fuel compartment. The reentry module of the Soyuz was replaced with an unpressurized propellant and refueling compartment with ducting along the outside of the spacecraft. This meant that if a leak occurred the poisonous gas would not enter the station's atmosphere. The fuel was carried in two tanks.
• A propulsion module. The propulsion module, at the rear of the spacecraft, remained unchanged and contained the orientation engines used for the automatic docking.

Reduction in weight was accomplished because the Progress was designed to be unmanned and unreturnable. This meant that there was no need for bulky life support systems and heat shields. The spacecraft also had no ability to split into separate modules. After undocking, the spacecraft performed a retrofiring and burnt up harmlessly in the atmosphere.

The bureau in charge of designing the freighter was TsKBEM (now RKK Energia). They began work on the design in mid-1973, giving the Progress the highly descriptive designation 11F615A15. The design was complete by February, 1974, and the first production model was ready for launch in November 1977. Progress 1 launched on January 20, 1978 aboard the same rocket used to launch the Soyuz. It still featured the same launch shroud as the Soyuz, though this was purely for aerodynamic purposes as the launch escape system had been deactivated.

This first version of Progress had a mass of 7,020 kg and carried 2,300 kg of cargo, or 30% of its launch weight. It had the same diameter as the Soyuz at 2.2 metres, but was 8 metres in length—slightly longer. The autonomous flight time was 3 days, the same time as that of the Soyuz ferry. It could spend one month docked. Progress always docked to the aft port of the station it was resupplying.

This version of the Progress was used until 1986, when it was replaced with the Progress M. This was essentially the same spacecraft as the original Progress, but it featured improvements from the Soyuz T and Soyuz TM. It could spend up to 30 days in autonomous flight and was able to carry 100 kg more to Mir. Also, for the first time, it could return items to Earth. This was accomplished by using the Raduga capsule, which could carry up to 150 kg of cargo. It was 1.5 m long and 60 cm in diameter and had a "dry weight" of 350 kg. For the first time, Progress could dock to the forward port of the station and still transfer fuel. It also used the same rendezvous system as the Soyuz and featured solar panels for the first time.

This spacecraft is still in use today for the International Space Station. It is currently the only spacecraft available to transport large quantities of supplies to the station, as the Space Shuttle remains grounded after the breakup of the Columbia at the end of STS-107. For ISS missions, the Progress M1 variant is used, which moves the water tanks from the propellant and refueling module to the pressurized section, and as a result is able to carry more propellant.

Like the Soyuz (but in contrast to almost all American space ships), the Progress has an autonomous navigation system that usually allows for automatic docking with the space station, but can be manually overridden if necessary.

The European Space Agency (ESA) is planning its own supply freighter called the Automatic Transfer Vehicle. The first of these, the Jules Verne, is due for launch in the second half of 2005. It will be able to carry up to 7.5 tonnes of cargo into space, roughly three times as much as the Progress, and will be launched every 12 months by an Ariane 5 rocket.

Progress specifications

• Launch weight 7,020-7,249 kg
• Weight of cargo (Progress 1-24) ~2,300 kg
• Weight of cargo (Progress 24-42) ~2,500 kg
• Length 7.94 m
• Diameter of cargo modules 2.2 m
• Maximum diameter 2.72 m
• Volume of cargo compartment 6.6 m³

Progress M specifications

• Launch weight 7,130 kg
• Cargo weight 2,600 kg
• Dry cargo weight 1,500 kg
• Liquid cargo weight 1,540 kg
• Length 7.23 m
• Solar array span 10.6 m
• Dry cargo compartment volume 7.6 m³
• Diameter of cargo modules 2.2 m
• Maximum diameter 2.72 m

See also

• List of unmanned spaceflights to the ISSde:Progress

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