On the accuracy of satellite reentry predictions

In January 2002, the Inter-Agency Space Debris Coordination Committee (IADC) promoted a fourth reentry test campaign, choosing an old Russian upper stage as a study case. As in the past, ISTI - formerly CNUCE - was involved, acting as the Italian Space Agency (ASI) technical contact, in the modeling aspects of the reentry predictions, while other IADC members, namely NASA, Rosaviakosmos and ESA, also provided periodic orbits determinations based on ground sensor data. The test campaign took place in a period of high solar activity, during the second peak of the cycle 23 maximum. This was a good opportunity to investigate the behavior of the models available or developed at ISTI, in terms of atmospheric density description, extreme ultraviolet radiation input, ballistic parameter estimation and orbit propagation. In order to evaluate the intrinsic reentry prediction uncertainties, the orbital decay of the test object was fitted, and predictions were made for it, using three different thermospheric density models and two independent sets of orbit determinations (American and Russian two-line elements). The results obtained were compared in order to provide a quantitative assessment of the level of accuracy that may be expected in similar situations.