XNAV Beyond the Moon

Paul Graven, John Collins, Suneel I. Sheikh, and John E. Hanson

Abstract:	In 2006, Microcosm executed a Phase I Small Business Innovative Research (SBIR) project for NASA exploring applications for XNAV beyond geosynchronous orbit. This paper provides a brief overview of the basic principles of XNAV, followed by a discussion of elements of the navigation error budget. Then various applications will be explored, including Earth-Sun L2, planetary and very deep space missions. Performance comparisons relative to current solutions are presented. Phase I results demonstrated approximate, first-order navigation accuracy achievable using periodic X-ray sources that have been characterized and catalogued in recent years, demonstrating utility for some NASA mission applications. Sample use cases of interest to NASA were identified and investigated for implementation of XNAV either as an autonomous navigation capability or as an augmentation to current interplanetary navigation capability via the Deep Space Network (DSN). A first order error budget was developed that identified the key error sources and how they contribute to overall navigation error. The potential benefits of employing XNAV for future missions were also investigated for both relatively near and very far interplanetary missions. Microcosm is currently under a follow-on Phase II SBIR contract that will build upon the Phase I activities. This new phase will develop a detailed XNAV simulation capability to assist evaluating navigation performance for specific missions of interest, and create an XNAV flight software experiment ready to integrate on an appropriate near-term flight demonstration mission in Phase III of the program. The simulation will be targeted for integration with Goddard Space Flight Center’s GPS Enhanced Onboard Navigation System (GEONS) software. The XNAV error budget begun during Phase I will be developed in more detail to support the algorithm and simulation work.
Published in:	Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007) April 23 - 25, 2007 Royal Sonesta Hotel Cambridge, MA
Pages:	423 - 431
Cite this article:	Graven, Paul, Collins, John, Sheikh, Suneel I., Hanson, John E., "XNAV Beyond the Moon," Proceedings of the 63rd Annual Meeting of The Institute of Navigation (2007), Cambridge, MA, April 2007, pp. 423-431.
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