Absolute Orbit Determination and Gravity Field Recovery for 433 Eros Using Satellite-to-Satellite Tracking

摘要

A navigation scenario involving two satellites orbiting the asteroid 433 Eros is studied. Using relative radiometric measurement types between both satellites, absolute orbit determination is achieved. Recent research has shown that for satellites in libration point orbits, satellite-to-satellite tracking is enough to estimate the absolute state of all satellites involved due to the asymmetry of the gravity field. In this study, the asymmetry in the gravity field of Eros is used to achieve similar results. The purpose of this application is not to provide a highly-accurate representation of the gravity field, but demonstrate that absolute orbit determination may be accomplished using inter-satellite observations in the presence of an unknown gravity field. The satellite constellation studied utilizes inter-satellite observations and minimal Earth based radiometric observations to obtain accurate corrections to both satellites' state and corrections to the spherical harmonic gravity model up to degree and order 5. A Cramér-Rao Bound analysis shows that the system is observable even with significant uncertainties in the initial state. Final filter state solutions reveal that the uncertainty of the satellites' position 3D-RMS is less than 56 m and the velocity is less than 0.006 m/s over 9 days of observation processing.