Test of an Orbiting Hydrogen Maser Clock System Using Laser Time Transfer
SMITHSONIAN ASTROPHYSICAL OBSERVATORY CAMBRIDGE MA
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We describe a joint SAONASA 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 clocks to measure the clocks long-term frequency stability tau 104 seconds will be made using laser time transfer from existing NASA laser tracking stations. We describe the design of the maser clock and its control systems, and the laser 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 implications of determining the spacecrafts location by an on-board GPS receiver, and of using microwave techniques for time and frequency transfer. The possibiliity of a joint SAONASAESA European Space Agency test with a second hydrogen maser and a microwave time and frequency transfer system will be dicussed in a separate paper.
- Lasers and Masers