AAS 99-203

Refinement of Satellite Ballistic Factors for the Estimation of Atmosphere Density Variations and Improved LEO Orbit Prediction

P. Cefola, A. Nazarenko, V. Yurasov

The Charles Stark Draper Lab, Cambridge, MA,


In an earlier work, Prof. Nazarenko discussed an atmosphere density tracking process that operates in parallel to the orbit determination process. This atmosphere density tracking program employs ballistic coefficient data observed over short arcs from multiple satellites. The process includes: 1. A procedure for constructing the density variations which operates on a 2 or 3 hour grid. 2. A procedure fore estimating the true ballistic coefficients of the employed satellites which operates on a 28 or 56 day interval (1 or 2 monthly solar cycles) 3. Procedures for forecasting he atmosphere density at future times. The present paper focuses on the improvement of the algorithm for estimating the tru ballistic coefficient of the employed satellites. The main aspect of this improvement consists of applying, for updating the ballistic factors of the non-standard satellites, a linear function of altitude to model the systematic errors. Numerical testing based on simulated data has been undertaken to include a proposal to work with the real data. The possibility of complex utilization of data from both NORAD and the Russian Space Surveillance System is discussed.