Tests of Magnetometer/Sun-Sensor Orbit Determination Using Flight Data

A magnetometer-based orbit determination batch e lter has been improved and tested with real e ight data from Dynamics Explorer 2 (DE-2), the Magnetic Field Satellite (MAGSAT), and the O rsted satellite. These tests have been conducted to determine the performance of a low-cost autonomous orbit determination system. The spacecraft’ s orbit, magnetometer biases, and correction terms to the Earth’ s magnetic e eld are estimated by this e lter. Synthesized sun-sensor data, in addition to real magnetometer data, are used to make the e eld model correction terms observable. The e lter improvements include a new dynamics model and consideration of a priori variancesforthee eldmodel corrections.Thebestperformancethathasbeenachieved withthise lterisamaximum position error of 4.48 km for a 2-day batch of DE-2 data with second-order/degree e eld model corrections and 2.35 km for a 24-h batch of MAGSAT data with second-order/degree e eld model corrections. The maximum position error for a 24-h batch of O rsted data is 59.50 km without e eld model corrections, but is only 2.19 km with 10th-order/degree e eld model corrections.