Pointmass sensitivity of gravimetric satellites
Abstract
Frequencydomain expressions are found for gradiometer and satellitetosatellite tracking measurements of a point source on the surface of the Earth. The maximum signaltonoise ratio as a function of noise in the measurement apparatus is computed, and from that the minimum detectable point mass is inferred. A point mass of magnitude M_{3} = 100Gt gives a signaltonoise ratio of 3 when a GOCElike gradiometer passes directly over the mass. On the satellitetosatellite tracking mission GRACEFO M_{3} = 1.3Gt for the microwave instrument and M_{3} = 0.5Gt for the laser ranging interferometer. The sensitivity of future GRACElike missions with different orbital parameters and improved accelerometer sensitivity is explored, and the optimum spacecraft separation for detecting pointlike sources is found. The futuremission benefit of improving the accelerometer sensitivity for measurement of nongravitational disturbances is shown by the resulting reduction of M_{3} , to as small as 7 Mt for 500 km orbital altitude and optimized satellite separation of 900 km.
 Publication:

Advances in Space Research
 Pub Date:
 March 2021
 DOI:
 10.1016/j.asr.2020.12.019
 arXiv:
 arXiv:2006.08179
 Bibcode:
 2021AdSpR..67.1656S
 Keywords:

 GRACEFO;
 Laser ranging interferometer;
 Point mass sensitivity;
 Power spectral density;
 Optimal filter;
 Physics  Geophysics;
 Physics  Space Physics
 EPrint:
 doi:10.1016/j.asr.2020.12.019