Estimation of ballistic coefficients of low altitude debris objects from historical two line elements

This paper presents a new method for estimating ballistic coefficients (BCs) of low perigee debris objects from their historical two line elements (TLEs). The method uses the drag perturbation equation of the semi-major axis of the orbit. For an object with perigee altitude below 700 km, the variation in the mean semi-major axis derived from the TLE is mainly caused by the atmospheric drag effect, and therefore is used as the source in the estimation of the ballistic coefficient. The method is tested using the GRACE satellites, and a number of debris objects with external ballistic coefficient values, and agreements of about 10% are achieved.The method is also applied to estimate the BC values of three low perigee debris objects, which were tracked optically in May 2012 by the EOS Space Debris Tracking System. The single-station sparse tracking data of the three debris objects is processed using the orbit analysis software developed at EOS Space Systems. When tracking data of only 2 passes over about 24 h is available, the errors of orbit predictions for 24 h are mostly smaller than 100 arc seconds using the estimated BC values from the new method – significantly smaller than prediction errors obtained using other BC estimations.