Space Regulatory Glossary Orbital Mechanics

Kessler syndrome

/ˈkɛslər ˈsɪndroʊm/ noun

1. A theoretical scenario in which the density of objects in low Earth orbit reaches a tipping point where collisions generate debris faster than it naturally decays, creating a cascading chain reaction that renders entire orbital bands unusable for generations.
2. First described by NASA scientist Donald Kessler in 1978. The concept is the foundational rationale behind orbital debris mitigation regulations, including the FCC's five-year deorbit rule, and is driving investment in active debris removal technologies.

Origin Named after Donald J. Kessler, whose 1978 paper 'Collision Frequency of Artificial Satellites: The Creation of a Debris Belt' (co-authored with Burton G. Cour-Palais) established the mathematical framework for cascading debris collisions.

Read: The FCC 5-Year Deorbit Rule

Related terms

orbital debris Non-functional human-made objects in Earth orbit, including defunct satellites, spent rocket stages, fragmentation… Five-Year Rule An FCC rule adopted in September 2022 (effective September 2024) requiring satellite operators in low Earth orbit to… active debris removal The use of dedicated spacecraft to physically capture and deorbit existing orbital debris — as opposed to mitigation… conjunction assessment The process of predicting and evaluating potential close approaches between objects in orbit.

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