  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.
