Geosynchronous orbit determination using space surveillance network observations and improved radiative force modeling

Abstract

Correct modeling of the space environment, including radiative forces, is an important aspect of space situational awareness for geostationary (GEO) spacecraft. Solar radiation pressure has traditionally been modeled using a rotationally-invariant sphere with uniform optical properties. This study is intended to improve orbit determination accuracy for 3-axis stabilized GEO spacecraft via an improved radiative force model. The macro-model approach, developed earlier at NASA GSFC for the Tracking and Data Relay Satellites (TDRSS), models the spacecraft area and reflectivity properties using an assembly of flat plates to represent the spacecraft components. This 'box-wing' approach has been adapted for the UNIX version of the Goddard Trajectory Determination System (GTDS) at the MIT/Lincoln Laboratory. This thesis presents background and mathematical development of the macro-model approach. This thesis also describes software development and testing, including incorporation of a one-panel spacecraft model along with the full macro-model. A model for Earth albedo and Earth infrared radiation and related software development is also described. Additionally, this thesis gives details about the TDRSS macro-model, and explains the development of a macro-model for the NASA Geosynchronous Operational Environmental Satellites (GOES) I-M spacecraft. Results of simulated data testing using the improved radiative force models are presented. The real data testing detailed in this thesis is an investigation into improving GEO orbit determination using the new force models along with observation data from the Space Surveillance Network (SSN). For the TDRSS spacecraft, HANDS optical observations are used in conjunction with the SSN data.

(cont.) NOAA ranging observations are included in some of the tests for the GOES-10 spacecraft. The space-based visible (SBV) observation model has also been incorporated into GTDS, and SBV observations are included in the orbit determination testing. The tests combine the various types of observation data, and implement various observations corrections and biases. The results of this thesis give a better understanding of the process of determining precise orbits for GEO spacecraft with the box-wing model and SSN observations.