Extracting GEO orbit populations from optical surveys

Abstract

A number of optical instruments are involved in making systematic surveys of the geosynchronous Earth orbit (GEO) region. Because of the limited field of view of an optical instrument, it is impossible at any one time to observe objects in all orbit planes in the region. Therefore, the orbit distributions seen are biased relative to the true populations of orbits in space. Because the observations represent a statistical sample of the population, statistical variations must be accounted for. The full procedure to remove the biases is extremely difficult with the limited orbit data measured because objects in GEO can have a wide spectrum of possible orbits. The measurements themselves are often insufficient to distinguish whether the object is in an elliptical or circular orbit. However, by limiting the range of possible orbit types it is possible to simplify the problem and obtain reasonable orbit distribution estimates. These distributions can in turn be used to identify interesting groupings of objects that may be part of an unrecognized breakup event. This paper describes the methods used to remove observational biases, and presents estimates of orbit distributions of uncatalogued objects at GEO visible to the instruments.