Application of onboard radar to collision detection

For the collision detection is based on the orbit prediction, the most dangerous debris is the one big enough to destroy the spacecraft but could not be tracked and catalogued by the ground-based surveillance net. The radar equipped on the large-scale spacecraft could track such kind of debris to supplement the space objects catalogue and propagate for the collision detection. The onboard radar has the shorter tracking duration than that of the ground-based radar. For an uncatalogued space object, the batch or least-squares estimation method should need the sufficient tracking data to meet the precision of the preliminary orbit. On the other hand, for a cataloged object, the known orbit information could be used to propagate the state vector at the time of each measurement and the sequential estimator or filter is employed to improve the priori orbit information. And the updating rate of the orbit information can be computed according to the orbital space-time relationship between the two objects. Then the new orbital information could modify the orbital propagation to detect the objects which would most probably collide with the spacecraft.