Service module

A service module (also known as an equipment module or instrument compartment) is a component of a crewed space capsule containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacecraft, the service module serves a storehouse of critical subsystems and supplies for the mission such as electrical systems, environmental control, and propellant tanks. The service module is jettisoned upon the completion of the mission, and usually burns up during atmospheric reentry.

The Russian phrase for service module for the Soyuz spacecraft is sometimes more directly translated "Instrument-Assembly Compartment". This comes from the design feature of having the guidance and other computer systems in a separate pressure chamber (the instruments) from the rocket engines, their propellant tanks, and the life support tanks (from the German Aggregat, which gets translated "assembly"). The Russians use the term "module" (модуль) primarily in regards to elements of a modular space station, e.g. the Zvezda Service Module.

Design

Depending upon the spacecraft architecture and system design, a typical service module usually contain the following: Zvezda was launched on a Proton launch vehicle on 12 July 2000, and docked with the Zarya module on 26 July 2000.

Soyuz service module

At the back of the Soyuz spacecraft is the Service Module. It has a pressurized container shaped like a bulging can (instrumentation compartment, priborniy otsek) that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. A non-pressurized part of the Service Module (propulsion compartment, agregatniy otsek) contains the main engine and a liquid-fuelled propulsion system for maneuvering in orbit and initiating the descent back to Earth. Outside the Service Module are the sensors for the orientation system and the solar array, which is oriented towards the Sun by rotating the ship.

Shenzhou service module

The aft service module of the Shenzhou spacecraft contains life support and other equipment required for the functioning of Shenzhou. Two pairs of solar panels, one pair on the service module and the other pair on the orbital module, have a total area of over 40 m2 (430 ft<sup>2</sup>), indicating average electrical power over 1.5 kW.

European Service Module (Orion)

The European Service Module is the service module component of the Orion spacecraft, serving as its primary power and propulsion component until it is discarded at the end of each mission. The service module supports the crew module from launch through separation prior to reentry. It provides in-space propulsion capability for orbital transfer, attitude control, and high altitude ascent aborts. It provides the water and oxygen needed for a habitable environment, generates and stores electrical power, and maintains the temperature of the vehicle's systems and components. This module can also transport unpressurized cargo and scientific payloads.

List of past service modules

Retired

Vostok equipment module
Voskhod equipment module
Gemini equipment module
Apollo Service Module
Apollo Lunar Module descent stage

Canceled

CSTS service module (canceled)
Kliper service module (canceled)
Hermes resource module (canceled)