Operational Collision Avoidance with Regard to Catalog Objects

Abstract

In previous chapters all collision flux estimates and corresponding collision probabilities were purely based on stochastic methods which did not consider the estimated orbital positions of objects. While orbits of the whole debris population were propagated across the historic evolution of the environment, the coarse first-order prediction methods were only used to derive time histories of spatial object densities and transient velocities in a gridded 3D control volume. Such statistical assessments are justified for small debris objects which were generated by stochastic release models into orbits with poorly known initial conditions. For larger-size objects, however, USSTRATCOM is maintaining a catalog of tracked objects (see Chapter 2), with routinely updated orbit information in a so-called Two-Line Element (TLE) format. When used with care, such data can be employed to improve the safety of operational spacecraft by means of a conjunction prediction and collision warning service for missions in densely populated orbital regions.