2A10 - Laser experiments for determining satellite orbits

The results from a series of experiments at the Smithsonian Astrophysical Observing Station, Organ Pass, N. Mex., indicate how lasers may be used to supplement the worldwide network of Baker-Nunn cameras in obtaining precise satellite orbits for geodesy and other purposes. A pulsed ruby laser and photoelectric receiver were located at the observing station. Laser returns were obtained from the three satellites equipped with retroreflectors. The problem of aiming the laser so that its narrow beam reaches the satellite is discussed for the cases of the satellite in sunlight and in shadow. The value of the limiting range obtained experimentally is compared with that calculated from the range equation and from measurements and estimates of the background noise. Range measurements made with the laser system are compared with values determined from the orbit computations based on observations from the Baker-Nunn network. The effects of the earth´s atmosphere are discussed.