GPS IIR Joins the GPS Constellation

Kevin Kiser, Scott H. Vaughan

Abstract:	This paper introduces the new generation of GPS spacecraft, the GPS IIR series (II for block two and R for replenishment). The GPS IIR spacecraft will be launched over the next few years to replenish the existing GPS II/IIA constellation. A total of 21 GPS IIR spacecraft will be launched. Lockheed Martin Missiles and Space (LMMS) builds the GPS IIR and the United States Air Force Space Command's 50th Space Wing operates the GPS constellation. 23 July 1997 marked the first successful GPS IIR spacecraft launch. The launch was followed by four months of on-orbit testing to "shake-out" the new spacecraft design and supporting ground systems. This paper discusses differences between GPS IIR and GPS II/IIA spacecraft, and the performance of the GPS IIR spacecraft during the early orbit operations. This paper also discusses the preliminary spacecraft bus and mission performance characteristics of the GPS IIR spacecraft determined through the on-orbit test period. Special emphasis is placed on a discussion of the key features of the GPS IIR spacecraft that enhance the availability of the system to the users.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1915 - 1923
Cite this article:	Kiser, Kevin, Vaughan, Scott H., "GPS IIR Joins the GPS Constellation," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1915-1923.
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