Relative Navigation of Spacecraft Utilizing Bright, Aperiodic Celestial Sources

Suneel I. Sheikh, Paul S. Ray, Kathryn Weiner, Michael T. Wolff, and Kent S. Wood

Abstract:	Absolute position determination of a single spacecraft can be accomplished utilizing X-ray observations of stable, periodic signals from celestial sources such as pulsars [1]. The utility of this method can be limited by the intrinsic faintness of the signals from the most stable X-ray pulsars, which mandates the use of large area X-ray detectors. However, for many applications, including spacecraft flying in formation for coordinated communication and scientific measurements, only relative range information to another spacecraft is required. Assuming two separate spacecraft carry X-ray detectors, it will be shown that this application does not require the use of stable, periodic X-ray sources. Instead, by crosscorrelating the signal received at the two spacecraft from bright X-ray sources that have a large amount of aperiodic variability (e.g. flickering, shot noise, broad band noise, or quasi-periodic oscillations) the distance between the two spacecraft projected in the direction of the X-ray source can be determined directly. Multiple observations of sources in different directions can then be used to fully determine the relative position of the two spacecraft, while requiring only modest size X-ray detectors. Methods to compute this signal cross-correlation are presented. The potential performance of this method is evaluated using realistic simulations of source light curves with Poisson statistics, as well as observations of the most promising X-ray sources made with NASA’s Rossi X-ray Timing Explorer.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	444 - 453
Cite this article:	Sheikh, Suneel I., Ray, Paul S., Weiner, Kathryn, Wolff, Michael T., Wood, Kent S., "Relative Navigation of Spacecraft Utilizing Bright, Aperiodic Celestial Sources," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 444-453.
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