Enhancing the precision limits of interferometric satellite geodesy missions

TL;DR

This paper explores advanced noise reduction techniques, including time-delay interferometry, differential satellite formations, and quantum optics, to significantly improve the measurement precision of satellite geodesy missions like GRACE-FO.

Contribution

It introduces novel methods for noise mitigation in satellite geodesy, demonstrating potential for nearly three orders of magnitude improvement in measurement accuracy.

Findings

Time-delay interferometry can remove laser phase noise.

Differential satellite formations enhance signal-to-noise ratio.

Quantum optics techniques show promise for reducing quantum noise.

Abstract

Satellite geodesy uses the measurement of the motion of one or more satellites to infer precise information about the Earth's gravitational field. In this work, we consider the achievable precision limits on such measurements by examining approximate models for the three main noise sources in the measurement process of the current Gravitational Recovery and Climate Experiment (GRACE) Follow-On mission: laser phase noise, accelerometer noise and quantum noise. We show that, through time-delay interferometry, it is possible to remove the laser phase noise from the measurement, allowing for almost three orders of magnitude improvement in the signal-to-noise ratio. Several differential mass satellite formations are presented which can further enhance the signal-to-noise ratio through the removal of accelerometer noise. Finally, techniques from quantum optics have been studied, and found to have great promise for reducing quantum noise in other alternative mission configurations. We model the spectral noise performance using an intuitive 1D model and verify that our proposals have the potential to greatly enhance the performance of near-future satellite geodesy missions.