Lorentz Accelerations in the Earth Flyby Anomaly

DOI: 10.2514/1.47413 Mission engineers have detected an unexpected anomaly on six spacecraft during low-altitude gravity-assist maneuvers around Earth. This Earth flyby anomaly involves an acceleration that, to date, researchers cannot account for based on known forces or errors in measurement or modeling. This paper evaluates Lorentz accelerationsassociatedwithspacecraftelectrostaticchargingasapossibleexplanationfortheEarth flybyanomaly. This analysis does not explicitly address plasma physics but, instead, bases its conclusions on fundamental six-state flight dynamics. The analysis focuses on the Near Earth Asteroid Rendezvous spacecraft, because it exhibited the largest anomalous error with the smallest estimated residuals. The analysis takes the form of a boundary-value probleminwhichvector-disturbance timehistoriesarefoundnumerically throughnonlinearoptimizationmethods. The analysis identifies the unknown, but required, acceleration based on a model of the Lorentz-force interaction. The algorithm cannot converge on a solution that fully reproduces the anomalous error in all six orbital states. It is unlikely, based on this analysis, that Lorentz forces cause the flyby anomaly.