Sponsored by NASA Goddard Space Flight Center
Project Participants: Mark L. Psiaki (PI) and Hee Jung
Batch filters and Kalman filters are being developed that use magnetometer data to determine orbit or to provide a back-up mode attitude determination capability. This work seeks to take advantage of the universal presence of magnetometers on spacecraft in order to substitute for data from sensors that may be too costly for some missions or that may fail. The orbit determination work is extending previous results by enhancing the performance of an existing magnetometer-based batch orbit determination filter. The enhancements will improve the orbital dynamics model and will allow for the use of additional available sensor data. The goal of the work is to improve the current state of the art in magnetometer-based orbit determination from the 5-10 km accuracy range to the 1 km range.
Another version of this filter will integrate the orbit and attitude determination functions in a recursive extended Kalman filter. Its goal will be to further reduce orbital estimation uncertainty to below 1 km.
Additional attitude determination work is developing Kalman filters that have improved dynamic models. These dynamic models seek to enable accurate attitude state propagation when complete 3-axis rate gyro information is not available. Such techniques will enhance the ability to do back-up attitude determination for systems whose rate gyros suffer failures, and they could be used to eliminate rate gyros from missions that otherwise would have used them. Initial work on this part of the project is concentrating on understanding the attitude excursions that occurred on the Hubble Space Telescope when it was forced to operate in its zero-gyro sun pointing mode because of the failure of a number of its rate gyros.
Last updated 9 Feb. 2001