[American Institute of Aeronautics and Astronautics 54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law - Bremen, Germany (29 September 2003 - 03 October 2003)] 54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law - Guidance Scheme for Autonomous Electric Propelled Spacecrafts