Passivation
The process of removing all stored energy from a spacecraft at end of life to prevent accidental explosions that could create debris.
Passivation is a critical debris mitigation measure that eliminates explosion risk from decommissioned spacecraft by depleting or safing all energy sources.
Energy Sources to Address
- Propellant: Vent or burn remaining fuel
- Batteries: Discharge and disconnect
- Pressure Vessels: Vent pressurants
- Reaction Wheels: Spin down
- Solar Arrays: Disconnect from bus (optional)
Regulatory Requirement The EU Space Act proposal (COM(2025) 335, not in force) would require spacecraft to be passivated (Annex V point 1.2.1(e)-(f)) and, where a controlled re-entry cannot be performed as planned, to be passivated, provided this can be done in a safe, timely and controlled manner (point 3.5.7). Failure to passivate has been a major source of debris-generating events historically.
Timing Passivation should occur:
- After final mission operations
- Before loss of attitude control
- While ground contact is reliable
- Prior to deorbit maneuver (if applicable)
Verification Operators must:
- Document passivation procedures
- Confirm passivation execution
- Report to NCA upon completion
Historical Context Numerous debris-generating events have resulted from unpassivated upper stages and spacecraft, making this requirement essential for long-term orbital sustainability.