The United States Space Command (USSPACECOM) provides several important services for the Shuttle Program:
Satellite surveillance and tracking
Prediction of close conjunctions between the Orbiter and other space objects
"Threat and Warning" notifications
Communications
The FDO is responsible for all verbal contact with USSPACECOM
The FDO and Flight Director share responsibility for written traffic as per the ICD.
The FDO sends and receives trajectory-related messages
The Flight Director receives "Threat and Warning" messages
COMBOs
The FDO and USSPACECOM coordinate for Computations of Miss Between Orbits (COMBOs).
COMBO messages are sent to the FDO from the Space Defense Operations Center (SPADOC) according to a schedule agreed to before launch.
The FDO sends an Orbiter vector to SPADOC via the JSC Message Center once per shift and after major trajectory events.
SPADOC will perform COMBO analysis and report the results to the FDO within an hour of receiving the Orbiter vector.
If an object is within 5x25x5 km of the Orbiter, SPADOC will inform the FDO and increase ground tracking station tasking on the object.
The FDO will confirm the spacing seen by SPADOC (all final decisions will be based on this spacing).
If the object is within 2x5x2 km of the Orbiter, the FDO and Flight Director will coordinate an avoidance maneuver and determine if the maneuver should be performed.
Due to various inaccuracies, even if object is within the 2x5x2 km "box", the probability of a collision is still less than 1-in-100,000.
According to FR A4.1.3-6, the maneuver "should not compromise primary payload or mission objectives".
Orbit/Rendezvous
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