Service module - Definition

A spacecraft's service module is a compartment containing a variety of support systems used for spacecraft operations, but not any habitable area. Service modules are jettisoned when they are no longer needed, for example just before atmospheric reentry.

Service modules often contain:

• Fuel cells or Batteries to provide power to the spacecraft. (Batteries are also in the part of the spacecraft that reenters, to provide power during reentry.)
• Liquid oxygen (LOX) for fuel cells and breathing.
• Liquid hydrogen (LH2) for fuel cells.
• Helium to force liquids to their destinations.
• Guidance equipment
• Propulsion engine and fuel
• Reaction Control System engines

Spacecraft with service modules include:

• Soyuz spacecraft (Soviet/Russian)
• Gemini spacecraft (American)
• Apollo spacecraft (American)
• Shenzhou spacecraft (Chinese)

Example Usage of Service