Gravitational Acceleration Maps for Initialization and Ambiguity Resolution of Pulsar-Based PNT in Space

Kyle J. Houser Joel T. Runnels, Demoz Gebre-Egziabher

Abstract:	A method to resolve initialization ambiguities encountered in x-ray-based pulsar navigation in deep space is presented. Prior work has shown that x-ray signals from pulsars can be used to determine the position of a spacecraft relative to its starting point. However, determining the initial position is still a challenge. This challenge is addressed in this paper by developing an algorithm which uses gravitational acceleration “maps” that are a function of a spacecrafts position in the solar system. We show that the spacecraft acceleration can be estimated from the Doppler shift of pulsar signals tracked by a spacecraft. Given the acceleration estimate, one can place the location of the spacecraft in the acceleration map. The proposed algorithm is validated using observation data from the Neutron Star Interior Composition Explorer (NICER) observatory aboard the International Space Station (ISS). It shown that the method can provide an initial position estimate that is accurate within 1 4 of the period of many pulsars that are proposed for use in deep space navigation.
Published in:	Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022) September 19 - 23, 2022 Hyatt Regency Denver Denver, Colorado
Pages:	1917 - 1932
Cite this article:	Runnels, Kyle J. Houser Joel T., Gebre-Egziabher, Demoz, "Gravitational Acceleration Maps for Initialization and Ambiguity Resolution of Pulsar-Based PNT in Space," Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022), Denver, Colorado, September 2022, pp. 1917-1932. https://doi.org/10.33012/2022.18542
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