Satellite tracking using ambient RF (STAR): orbit estimation

摘要

The STAR initiative was proposed to demonstrate the ability to use ambient RF energy to reliably detect and track space objects in a "bistatic" configuration. In a bistatic geometry, the source of electromagnetic energy is physically displaced from a receiver which collects the reflected energy from the space object of interest. Bistatic range-rate and range observations were obtained for selected Low Earth Orbiting (LEO) satellites and the previously known initial state vector was updated using a least-squares differntial correction methodology to generate an improved sate estimate. For those cases where an initial state vector is not available, an initial orbit determination methodology, designed specifically for STAR, was used to generate the initial state vector. In some cases, truth data was available from laser-ranged measurements of the satellite's position. The results depend on several factors including the number of observations, the number of transmitters used, and the aspect angles associated with the viewing geometry. Optimization of these dependencies yields state vector estimates that are within 100 meters of the laser-ranged truth values.