Debris & Reentry
Space debris — defunct satellites, spent rocket stages, and fragmentation fragments — poses a growing threat to active spacecraft. With over 45,000 tracked objects larger than 10 cm and hundreds of thousands of smaller pieces, the risk of collision is real and rising. Conjunction screening, collision avoidance maneuvers, and end-of-life disposal are now routine operational requirements for any responsible satellite operator.
Terms in this Category
Space Debris
Any human-made object in orbit that no longer serves a useful function, including defunct satellites, spent rocket stages, and fragments from collisions or breakups.
Reentry
The return of a space object into Earth's atmosphere, whether controlled or uncontrolled.
Decay
The reentry or loss of orbital altitude that removes an object from sustained orbit.
Conjunction
A close approach between two tracked objects that may require additional monitoring or maneuver planning.
Collision Avoidance
The process of predicting and preventing close approaches between active spacecraft or between spacecraft and debris.
Debris Mitigation
Measures taken during spacecraft design, operation, and disposal to prevent the creation of new orbital debris.
End-of-Life Disposal
The planned procedures and maneuvers performed at the end of a satellite's operational life to reduce its impact on the space environment.
Propulsive Disposal
The planned use of onboard propulsion to deorbit or relocate a spacecraft at end of life.
SSA (Space Situational Awareness)
Legacy term often used for tracking and understanding activity in space; frequently overlaps with space domain awareness.
SDA (Space Domain Awareness)
Detection, tracking, characterization, and interpretation of activity in the space domain.
CAD (Close Approach Data)
Data describing a predicted close approach between tracked objects, often used for conjunction screening.
Frequently Asked Questions
How much space debris is there?
Over 45,000 objects larger than 10 cm are tracked. Estimates suggest 500,000 pieces between 1-10 cm and over 100 million particles smaller than 1 cm.
Can space debris be cleaned up?
Active debris removal missions are in development. ESA's ClearSpace-1 and Astroscale's ELSA-d aim to capture and deorbit defunct objects.
How do satellites avoid collisions?
Operators screen for conjunctions daily or weekly. When collision risk exceeds a threshold, they perform a collision avoidance maneuver (CAM).