Typical Cubesat Subsystems Typical EPS Subsystems Power System Definitions Requirements Major Interacting Subsystems Where to. Primary mission, Science needs, Mission length, Orbit definition, Mission life, System architecture, Cost, schedule, and reliability constraints. Determine average power from the Power Equipment List (PEL). Determine peak power from the Power Profile. Evaluate Mission Requirements. Evaluate Orbital or Site Parameters. Systems Propulsion and/or Reaction Control (RCS) Guidance, Navigation, and Control (GN&C) Communications (Comm) Command and Data Handling (C&DH) Structures and Mechanisms Thermal Control (TCS) Supply continuous Electrical Power to subsystems as needed during entire mission life (including nighttime and eclipses). Safely distribute and control all of the power generated.