Test of an Orbiting Hydrogen Maser Clock System Using Laser Time Transfer

Robert F.C. Vessot, Edward M. Mattison, G.U. Nystrom, Rudolph Decher

Abstract:	We describe a joint SAO/NASA program for flight testing an atomic hydrogen maser clock system design for long-term operation in space. The clock system will be carried by a shuttle-launched EURECA spacecraft. Comparisons with earth clock to measure the clock's long-term frequenq stability (r >10^4 seconds) will be made using her time transfer from existing NASA laser tracking stations. We describe the design of the maser clock and its control systems, and the her timing technique. We discuss the precision of station time synchronization and the limitations in the comparison between the earth and space time scales owin to gravitational and relativistic effects. We will explore the implication of determining the spacecraft location by an on-board GPS receiver, and of using microwave techniques for time and frequency transfer. The possibility of a joint SAO/NASA/ESA (European Space Agency) test with a second hydrogen maser and a microwave time and frequency transfer system will be discussed in a separate paper.
Published in:	Proceedings of the 23th Annual Precise Time and Time Interval Systems and Applications Meeting December 3 - 5, 1991 Pasadena, California
Pages:	401 - 415
Cite this article:	Vessot, Robert F.C., Mattison, Edward M., Nystrom, G.U., Decher, Rudolph, "Test of an Orbiting Hydrogen Maser Clock System Using Laser Time Transfer," Proceedings of the 23th Annual Precise Time and Time Interval Systems and Applications Meeting, Pasadena, California, December 1991, pp. 401-415.
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