LONG-TERM EVOLUTION OF UNCONTROLLED GEOSYNCHRONOUS ORBITS - ORBITAL DEBRIS IMPLICATIONS

Numerous objects have now been in uncontrolled geosynchronous orbits for many years. There are at least three different methods of analyzing the evolution of these orbits: analysis of U.S. Space Command tracking data; use of analytical and semi-analytical methods for predictions; and numerical orbit propagators. Comparing results obtained directly from tracking data with those obtained from analytical and numerical methods is important for possible orbital debris implications. In this paper new methods are described for analyzing, from historical ephemeris data, the orbital evolution of a class of objects in similar orbits. These graphical methods use Moser orbital elements and facilitate comparisons with theoretical predictions of orbital evolution. Application of these methods to uncontrolled geosynchronous orbits has manifested some important characteristics of the long-term evolution of these orbits, corroborating earlier theoretical predictions. An adequate explanation of one unexpected characteristic of the data remains to be found.