The Progress Delivery Vehicle (PDV)

The Progress Delivery Vehicle is a Russian spacecraft designed to bring supplies to cosmonauts and astronauts working on long-term missions in space. After the race to the moon in the 1960s, the American and Russian space programs moved in different directions.
 
While the Americans continued to pursue the exploration of our solar system, the Russians focused their energies on space stations orbiting the earth. For astronauts to survive on a space station, consumable materials need to be brought to them periodically.
 
A Progress Delivery Vehicle delivers these vital supplies. Typical cargo on a Progress craft includes:
  • clothing
  • fresh food
  • fuel
  • hardware for experiments, installation and repair
  • oxygen
  • water.
The Progress Delivery Vehicle also allows for removal of accumulated waste materials.

Early Attempts at Progress

When the Russians first began working on the idea of a delivery vehicle, the plan was to use the already existing Soyuz spacecraft. By the 1970s, it became clear that the Soyuz could not meet the demands of this project. Consequently, Russian rocket scientists worked on developing a new design for their delivery vehicle, deriving it from the Soyuz. The developer of the Salyut space stations, TsKBEM (currently RKK Energia), considered a number of different configurations, including:
  • manned and unmanned variations
  • options for returning cargo from space
  • size variations.

An unmanned design was eventually chosen, making the Progress Delivery Vehicle effective for one-way missions only.

The idea of returning cargo was not forgotten however. To work towards making these vehicles capable of returning cargo, Russian aerospace engineers designed a unique retrievable capsule, called Raduga, that could be incorporated into the Progress. As a result, the Progress may soon be able to return cargo to Earth.

Currently, the Progress is sent back to the Earth's atmosphere to burn up after making space deliveries. This still allows for the essential function of waste removal from space stations.

The Completed Progress Craft

The PDV is in some ways very similar to the Soyuz. Its propulsion and service systems are built in the tail of the vehicle, as they were in the Soyuz. Similarly, the Progress also has a pressurized compartment for supplies that resembles the Cosmonauts' living area on the Soyuz.

In place of the Soyuz's reentry module is an un-pressurized propellant and refueling compartment. This is an important safety feature during docking because it keeps these dangerous substances outside the pressurized compartments of the space station. Any leaks that might occur would not affect the cosmonauts' atmosphere.

The First Progress Craft
The very first Progress Delivery Vehicle was built in November 1977. It was launched on Jan. 20, 1978, to bring supplies to the Salyut 6 station. Over the following years, a total of 43 original design Progress vehicles delivered essentials to the cosmonauts working on the Salyut 6 and Salyut 7 space stations, making it possible for them to break both their own and U.S. records for the duration of space missions.

Later Progress Designs

Since 1977, the Progress Delivery Vehicle has been improved and updated. Newer models include:
  • Progress M: This craft was developed in 1986 and first launched in 1989 to bring supplies to the Mir space station. The Progress M has a more modern flight control system than the original Progress vehicle.

  • Progress M1: The M1 is the basic Progress model used today. It was first launched in February 2000 to refuel and re-supply the Mir space station. Then, in August of the same year, the first M1-3 model was launched toward the International Space Station. The M1 contains modifications to the propellant delivery system specifically designed for the needs of the ISS. It also contains a new digital flight control system.
Resources
 
Malik, Tariq (2004). Progress Cargo Ship Docks at ISS. Retrieved February 7, 2008, from the Space.com Web site.
 
The International Space Fellowship (2008). 30th Anniversary of Progress-1. Retrieved February 7, 2008, from The International Space Fellowship Web site.
 
Zak, Anatoly (2008). Spacecraft: Manned: Progress. Retrieved February 7, 2008, from the Russianspaceweb.com Web site.