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Navigation Using X-Ray PulsarsApproximately one dozen X-ray pulsars are presently known which emit strong stable pulses with periods of 0.7 to approximately 1000 s. By comparing the arrival times of these pulses at a spacecraft and at the Earth (via an Earth orbiting satellite), a three dimensional position of the spacecraft can be determined. One day of data from a small onboard X-ray detector yields a three dimensional position accurate to approximately 150 km. This accuracy is independent of spacecraft distance from the Earth. Present techniques for determining the two spacecraft coordinates other than range measure angles and thus degrade with increasing spacecraft range. Thus navigation using X-ray pulsars will always be superior to present techniques in measuring these two coordinates for sufficiently distant spacecraft. At present, the break even point occurs near the orbit of Jupiter. The Crab pulsar can also be used to obtain one transverse coordinate with an accuracy of approximately 20 km.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Chester, T. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Butman, S. A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 11, 2013
Publication Date
June 15, 1981
Publication Information
Publication: The Telecommun. and Data Acquisition Rept.
Subject Category
Space Communications, Spacecraft Communications, Command And Tracking
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.

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