Filtering of satellite-to-satellite observations

Abstract

This study addresses criticism of the low-low satellite-to-satellite methodology to obtain the small-scale gravitational structure of a primary gravitating body. Specifically, the aliasing of satellite-to-satellite range-rate observations from errors in the initial conditions of the orbits is studied numerically. It is shown that high-pass filtering effectively eliminates the aliasing of initial condition errors. In the case of the Lunar Polar Orbiter, ephemeris errors of at least 1 km can be tolerated. With two spacecraft in polar orbits, a data storage capability would provide global data coverage. Solution for the small-scale gravitational structure would probably be best achieved by an iterative approach using regional solutions. To this end, a simplified algorithm has been developed that can be used in feasibility studies. The performance of the algorithm is compared with simulated data.