A Skin Tracking Radar Experiment Involving the COURIER Satellite

Range measurements are a very powerful type of tracking data for spacecraft operating at interplanetary distances. As a step in the development of a technique for making such measurements, an experimental system was devised in which the technique was adapted to the radar tracking of artificial Earth satellites. The system was tried out by tracking the Echo balloon and, after modifications, proven by tracking the Courier satellite. This paper describes the system that was used and the experiments that were conducted. Evaluation of the range data was made by comparing it with angle and Doppler data. The comparison was made by computing an orbit from angle and Doppler data obtained on three successive passes. The range was computed from the orbit for comparison with the measured range. The ranges measured were between 1,900,000 and 2,500,000 meters, and the largest disagreement between the measured and computed range during these three passes was 36 meters which is only about twice the estimated uncertainty in the range measurement. The average disagreement was approximately 20 meters or one part in 10⁵. At the present it is not possible to state what part of the disagreement should be attributed to the ranging system and what part should be attributed to the orbit computation. The direction to be taken by further investigation is given.