Which five subsystems make up a typical spacecraft bus?

• A. Propulsion and thrust; thermal control; electrical power; guidance and navigation; communications and data handling.
• B. Electrical power, attitude control, navigation, Structural, and radiation detection.
• C. Structural, thermal control, electrical power, payload, and booster separation.
• D. Attitude control, electrical power, launch control, thermal control, structural.

Answer: (A)

Think of the spacecraft bus as the platform that keeps the mission possible by providing the basic, non-payload support functions: energy, motion, temperature control, orientation, and data exchange. The five subsystems listed in the correct choice cover exactly those core platform needs. Propulsion and thrust handle orbit changes and attitude adjustments, thermal control keeps all equipment within safe temperature ranges, electrical power supplies the energy the bus and payload need, guidance and navigation determine and control where the spacecraft is pointing, and communications and data handling manage onboard processing and the link to ground stations.

The other options mix in items that aren’t typically considered standard bus subsystems: structure is a separate, foundational element rather than a dynamic subsystem; payload or specific launch-related functions aren’t part of the bus during normal operation; radiation detection isn’t a universal bus function. The set that includes propulsion, thermal control, power, guidance/navigation, and communications/data handling best represents the typical bus architecture that supports a spacecraft’s mission.