Deriving Accurate Satellite Ballistic Coefficients from Two-Line Element Data

Abstract

Using a specially developed orbital propagator, it is shown that only two-line element data are required to accurately predict a satellite’s ballistic coefficient. By analyzing orbit degradation due to atmospheric drag, a ballistic coefficient can be estimated using an inexpensive way to determine an important satellite characteristic, without the need for additional satellite information or a design model. As atmospheric drag is a significant perturbing force for satellites in low Earth orbit, any improvements in its estimation are vital for many applications, such as reentry predictions, satellite lifetimes, and orbital evolution. The motivation for this work originates from the study of longterm thermospheric density changes. The publicly available two-line element catalog of currently orbiting and decayed objects is a vast resource of atmospheric density information. However, two-line element data modestly provide orbital ephemerides with an accuracy of hundreds of meters up to a few kilometers. Therefore, due to these inaccuracies, deriving an accurate estimate of ballistic coefficient requires an averaging technique using multiple estimates from multiple two-line element sets.