Zvezda (ISS Module) - Design

Design

Zvezda consists of a cylindrical "Work Compartment" where the crews work and live, a cylindrical "Transfer Chamber" which has one docking port, an unpressurized "Assembly Compartment" surrounding the Transfer Chamber, and a spherical "Transfer Compartment" with three docking ports (four docking ports total). The component weighs about 18,051 kg (39,800 lb)) and had a length of 13.1 metres (43 ft). The solar panels extend 29.7 metres (97 ft).

The "Transfer Compartment" attaches to the Zarya module, and has docking ports intended for the Science Power Platform and the Universal Docking Module. As in the early days of Mir, the transfer compartment provides a suitable EVA airlock where spacewalkers in Orlan suits removed a hatch after closing a few that connected the compartment to the rest of the station. It was used only during Expedition 2, where two men put a docking cone on the nadir port. The lower port connects to Pirs and the top port connects to Poisk. Eventually, the plan for Pirs is for it to be deorbited and replaced by the Multipurpose Laboratory Module.

The "Assembly Compartment" holds external equipment such as thrusters, thermometers, antennas, and propellant tanks.

The "Transfer Chamber" is equipped with automatic docking equipment and is used to service Soyuz and Progress spacecraft.

Zvezda can support up to six crew including separate sleeping quarters for two cosmonauts at a time. It also has a NASA-provided Treadmill with Vibration Isolation System and a bicycle for exercise, a toilet and other hygiene facilities and a galley with a refrigerator and freezer. The module contains the primary Russian computers for guidance and navigation. Zvezda has 14 windows—three 9-inch-diameter (230 mm) windows in the forward Transfer Compartment, a 16-inch window in the Working Compartment, one in each crew compartment, and several more in various locations. It also contains the Elektron system that electrolyzes condensed humidity and waste water to provide hydrogen and oxygen. The hydrogen is expelled into space and the oxygen is used for breathing air. The condensed water and the waste water can be used for drinking in an emergency, but ordinarily fresh water from Earth is used. There are 16 small thrusters and two large thrusters for propulsion, and eight batteries for storing power.

The Elektron system has required significant maintenance work, having failed several times and requiring the crew to use the Solid Fuel Oxygen Generator canisters (also called "Oxygen Candles", which were the cause of a fire on Mir) when it has been broken for extended amounts of time. It also contains the Vozdukh, a system which removes carbon dioxide from the air based on the use of regenerable absorbers of carbon dioxide gas. Zvezda has been criticized for being excessively noisy and the crew has been observed wearing earplugs inside it.

Zvezda contains the ESA's Digital Management System, a computer that controls ISS.