Progress is of much the same size and shape as Soyuz. It consists of three modules:
Weight savings were accomplished by the fact the Progress was designed to be unmanned and unreturnable. This mena that there was no need for bulky life support systems and heat shields. There was also no ability for the spacecraft to separate into separate modules. After undocking the spacecraft performed a retrofired and burnt up harmlessly in the atmosphere.
The bureau in charge of designing the freighter was TsKBEM (now RKK Energia). They started designing in mid-1973, given the Progress the highly descriptive designation 11F615A15. The design was complete by February 1974 and the first production model was ready for launch November 1977. Progress 1 launched 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 for aerodynamic purposes as the launch escape system had been deactivated.
This first version of Progress had a mass of 7,020 kg and took 2,300 kg of cargo or 30% of launch weight. It had the same diameter as the Soyuz at 2.2 metres but was 8 metres in length - a little longer. The automonous flight time was 3 days, the same time as that of the Soyuz ferry. It could spend one month docked. Progress also always docked to the aft port of the station it was resupplying.
This version of the Progress was used right up until 1986 when it was replaced with the Progress M. This was basically the same as the original Progress but featured improvements from the Soyuz T and Soyuz TM. It could spend up to 30 days in autonomous flight and could 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. This could carry items of up to 150 kg back to Earth. 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 stations and still transfer fuel. It also used the same rendesvous system as the Soyuz and featured solar panels for the first time.
This spacecraft is still used today for the International Space Station. It is currently the only thing available for transporting large quantities of supplies to the station with the Shuttle grounded after the breakup of Columbia at the end of STS-107. The ESA are planning their own supply freighter called the Automatic Transfer Vehicle. The first of these, Jules Verne, is due for launch sometime in 2004. It will be able to carry up to 7.5 tonnes of cargo into space and will be launched every 12 months by an Ariane 5 rocket.