NASA - National Aeronautics and Space Administration

The 16-foot-long, 8,000-pound Pirs Docking Compartment is attached to the bottom, Earth-facing port of the Zvezda Service Module. It docked to the International Space Station on Sept. 16, 2001, and was configured during three spacewalks by the Expedition Three crew.

Pirs, also known as DC-1, launched Sept. 14, 2001, as ISS Assembly Mission 4R on a Russian Soyuz rocket. The Docking Compartment has two primary functions. It serves as a docking port for the docking of transport and cargo vehicles to the Space Station and as an airlock for the performance of spacewalks by two Station crewmembers using Russian Orlan spacesuits.

Image to left: Expedition 9 Commander Gennady Padalka, left, and NASA ISS Science Officer Mike Fincke work on their Orlan spacesuits inside Pirs. Credit: NASA

In addition, the Docking Compartment can transport fuel from the fuel tanks of a docked Progress resupply vehicle to either the Zvezda Service Module Integrated Propulsion System or the Zarya Functional Cargo Block. It can also transfer propellant from the Zvezda and Zarya to the propulsion system of docked vehicles -- Soyuz and Progress. The docking compartment's lifetime as part of the Station is five years. Image above: Diagram of the Pirs Docking Compartment. Credit: NASA

Pirs Technical Specifications Mass at launch 4,350 kilograms (9,590 pounds) Mass at orbital nsertion 3,580 kilograms (7,893 pounds) Reserve mass for deliverable cargoes 800 kilograms (1,764 pounds) Assembly orbit altitude 350 - 410 kilometers (217 - 255 miles) Working orbit altitude 410 - 460 kilometers (255 - 286 miles) Length with Docking Assembly extended 4.91 meters (16 feet) Maximum casing diameter 2.55 meters (8.4 feet) Pressurized compartment volume 13 cubic meters (459 cubic feet)