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The Lunar Gravity Ranging System for the Gravity Recovery and Interior Laboratory (GRAIL) Mission 总被引:1,自引:0,他引:1
William M. Klipstein Bradford W. Arnold Daphna G. Enzer Alberto A. Ruiz Jeffrey Y. Tien Rabi T. Wang Charles E. Dunn 《Space Science Reviews》2013,178(1):57-76
The Lunar Gravity Ranging System (LGRS) flying on NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission measures fluctuations in the separation between the two GRAIL orbiters with sensitivity below 0.6 microns/Hz1/2. GRAIL adapts the mission design and instrumentation from the Gravity Recovery and Climate Experiment (GRACE) to a make a precise gravitational map of Earth’s Moon. Phase measurements of Ka-band carrier signals transmitted between spacecraft with line-of-sight separations between 50 km to 225 km provide the primary observable. Measurements of time offsets between the orbiters, frequency calibrations, and precise orbit determination provided by the Global Positioning System on GRACE are replaced by an S-band time-transfer cross link and Deep Space Network Doppler tracking of an X-band radioscience beacon and the spacecraft telecommunications link. Lack of an atmosphere at the Moon allows use of a single-frequency link and elimination of the accelerometer compared to the GRACE instrumentation. This paper describes the implementation, testing and performance of the instrument complement flown on the two GRAIL orbiters. 相似文献
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Satellite-Satellite Laser Links for Future Gravity Missions 总被引:3,自引:0,他引:3
A strong candidate for use in future missions to map time variations in the Earth's gravity field is laser heterodyne measurements
between separate spacecraft. At the shortest wavelengths that can be measured in space, the main accuracy limitation for variations
in the potential with latitude is expected to be the frequency stability of the laser. Thus the development of simple and
reliable space-qualified lasers with high frequency stability appears to be an important goal for the near future.
In the last few years, quite high stability has been achieved by locking the second harmonic of a Nd:YAG laser to a resonant
absorption line of iodine molecules in an absorption cell. Such a laser system can be made quite robust, and temperature related
frequency shifts can be controlled at a low value. Recent results from laboratory systems are described. The Allan standard
deviation for the beat between two such lasers was 2 × 10−14 at 10 s, and reached 7 × 10−15 at 600 s.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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