Low-Earth Orbit Determination from Gravity Gradient Measurements

TL;DR

This paper presents a novel orbit determination method for Low-Earth-Orbiting satellites using gravity gradient measurements, demonstrating promising accuracy and potential for GPS-denied navigation.

Contribution

It introduces an adaptive hybrid least squares filter utilizing gravity gradients and validates it with real ESA data, showing improved orbit estimation.

Findings

Radial and cross-track errors are within tens of meters.

Along-track errors are significantly larger, over an order of magnitude.

Method shows promise for GPS-denied spacecraft navigation.

Abstract

An innovative orbit determination method which makes use of gravity gradients for Low-Earth-Orbiting satellites is proposed. The measurement principle of gravity gradiometry is briefly reviewed and the sources of measurement error are analyzed. An adaptive hybrid least squares batch filter based on linearization of the orbital equation and unscented transformation of the measurement equation is developed to estimate the orbital states and the measurement biases. The algorithm is tested with the actual flight data from the European Space Agency Gravity field and steady-state Ocean Circulation Explorer. The orbit determination results are compared with the GPS-derived orbits. The radial and cross-track position errors are on the order of tens of meters, whereas the along-track position error is over one order of magnitude larger. The gravity gradient based orbit determination method is promising for potential use in GPS-denied spacecraft navigation.