AUTONOMOUS SATELLITE NAVIGATION VIA KALMAN FILTERING OF MAGNETOMETER DATA

An autonomous orbit determination system for low earth orbiting spacec rafts is developed, simulation tested and examined using actual spacec raft data of the BREM-SAT mission. An extended Kalman-type filter is u sed to deduce a minimum error estimate of the spacecraft ephemeris by utilizing the knowledge of system and measurement dynamics, assumed st atistics of system noises and measurement errors, and initial conditio n information. The presented algorithm is based on the laws of orbital mechanics and the measurement of geomagnetic field magnitude. Since l ow earth orbits are fully observable from a sufficient number of measu rements of the strength of the Earth's magnetic field the determinatio n scheme is independent of spacecraft attitude. In most cases the accu racy is sufficient for low earth orbiting satellites and moreover it c an be used as a backup system to provide redundancy. Especially for sm all satellites the system is highly recommended because no additional hardware is required besides a magnetometer and computation time on th e on-board computer.