Deorbit

Deorbit is the process of removing a spacecraft from orbit and inducing reentry into Earth’s atmosphere, typically as an end-of-life operation to dispose of the vehicle and reduce space debris. The goal is to ensure that surviving fragments pose minimal risk to people and property while meeting debris mitigation practices.

Controlled deorbit involves a deliberate maneuver, usually a retrograde burn using onboard propulsion to lower the orbit’s perigee into the atmosphere. The reentry path is planned to ensure the main mass burns up and any remaining fragments fall into a designated area, often remote oceanic regions. Before deorbiting, systems may be passivated and inertial navigation verified to minimize collision risk with other objects.

Uncontrolled deorbit occurs when a spacecraft’s orbit decays due to atmospheric drag without a planned maneuver. This is more common for low Earth orbit objects and can be less predictable in timing and debris footprint, though modern guidelines seek to minimize risk by ensuring planful disposal and rapid deorbit when feasible.

In practice, deorbit planning is part of end-of-life procedures and debris mitigation standards, which may require deorbit into safe regions and timely disposal. For higher orbits, such as geostationary orbit, deorbit is generally impractical; missions instead use a graveyard or disposal orbit, keeping the operational orbit free of debris.

Reentry safety is influenced by the vehicle’s design, mass, and shielding; most of the energy is expended during atmospheric entry, causing substantial heating and fragmentation. The objective is to maximize burnup of the spacecraft while minimizing risk to people on the ground.