Project Echo: Satellite Tracking Radar

The operational plan of the Project Echo experiment provided for pointing of the transmitting and receiving antennas from calculated orbital data. The angle-tracking radar was intended as a "back up" to this system.* In operation the radar has been found to provide appreciably better pointing accuracy than is obtained from the computed data. As a result, the orbital data are employed only to keep the antennas pointed approximately on target, with the radar (or optical telescope during periods of visibility) providing for more exact alignment. According to the original concept the radar was intended to serve only the purpose of keeping the antennas positioned during communications experiments. In recent months these experiments have practically ceased, which leaves us with only the radar as a regular source of signal for studying transmission effects. Under the present plan of operation the balloon is tracked approximately once per week and its cross section determined from the strength of the reflected radar signal. * Although this equipment was designed by the Bell System as part of its research and development program, it was operated in connection with Project Echo under Contract NASW-110 for the National Aeronautics and Space Administration. 1157