The International Geophysical Year spurred the launch of the first artificial Earth satellites. The year was devoted to a study of the Earth and led to major gains in the field of geodesy. There is a good review on the subject at NOAA entitled Geodesy for the Layman. In the chapter on Satellite Geodesy there is a figure with a close-approach diagram similar to the one I used. I could not find a formula for the frequency vs time curve but that could mean at the time it was available elsewhere. Some of Guier's papers are cited in Kaula, Theory of Satellite Geodesy, 1966.