Satellite Maneuver Detection Using Two-line Element ( TLE ) Data

This paper summarizes the methods and limitations of deriving satellite maneuver information from historical twoline element (TLE) data. Each TLE contains the orbital information of an earth-orbiting object at a particular epoch time, and is used to calculate object state vectors. A TLE “time-history” comprises a list of TLEs measured over an extended period of time, and therefore contains information on orbital perturbation effects, both environmental and non-environmental. The non-environmental perturbations of interest for active satellites are thrusting maneuvers. This paper describes the design, implementation and performance of a TLE-based maneuver detection algorithm. Algorithm performance is measured relative to several spacecraft with known maneuver histories. TLE timehistories may also be used to estimate satellite masses, because the recorded environmental perturbations depend on a satellite’s area-to-mass ratio (A/m). Estimates of a “best-fit” A/m value for a satellite can be derived by performing a least-squares comparison of the orbital elements taken from the TLE history with analytically-derived orbital elements. However, in order for the least-squares analysis to yield an accurate A/m estimate, all forces that significantly perturb the orbit need to be appropriately modeled, including maneuver thrusting for active satellites. The focus of this work is on the development and assessment of techniques that allow maneuvers to be detected from the historical TLE data, and thus support trending of the A/m ratio. The results show surprisingly reliable detection of maneuvers down to delta-velocity magnitudes at the centimeter-per-second level or less, provided the algorithm parameters are “tuned” appropriately.