Low-Thrust Spacecraft Maneuver Determination Without Time/Magnitude Knowledge

The detection and estimation of spacecraft maneuvers, when the effects of that maneuver are not seen until after it occurs, are critical to ensuring the safety and efficacy of space traffic management and domain awareness. In this study, a new method is shown to determine the time, direction, and magnitude of small impulsive spacecraft maneuvers using a sequence of ground observations. The approach combines adaptive estimation techniques with relative linear models to provide recursive maneuver estimations. The nominal state of the spacecraft is perturbed and propagated forward in a particle-like filter manner, based on multiple-model adaptive estimation, using different assumed maneuvers until the time of each new observation. Maximum likelihood is used to provide an estimate of the time of the actual maneuver and enables subsequent estimation of the direction and magnitude of the maneuver. The forward propagation is enabled by state transition matrices, which allow the efficient propagation of large numbers of particles. The results are demonstrated for two different cases: a near-Earth case where Keplerian concepts can reduce computations by leveraging closed-form solutions and a general case presented through a cislunar scenario. The results demonstrate the effectiveness of the proposed method in the presence of measurement noise and process uncertainties and show potential for applications in both spacecraft operations and space domain awareness.