📘 Definition
Conjunction assessment is the process of screening the catalogue of tracked objects to identify predicted close approaches and evaluate collision risk. The US Space Force's 18th SDS performs routine screening for all catalogued objects. When a close approach is identified, a Conjunction Data Message (CDM) is issued containing the predicted miss distance, time of closest approach, and collision probability. Operators then decide whether to perform a collision avoidance manoeuvre. NASA's CARA team handles screening for NASA missions. The process must balance the cost of unnecessary manoeuvres against the risk of a collision.