The Genesis of the Idea

After working on techniques for improving the distance that radio waves could propagate for communications purposes, in the mid-1950s William E. (Bill) Gordon, Professor of Electrical Engineering at Cornell University, turned his attention to the possibility of measuring the electron density and temperature of the Earth’s upper atmosphere, the ionosphere, as a function of height using the backscattering of radio waves by the individual electrons present there. He laid out the specifications for such a radar system in a seminar in May 1958, pointing out that the radar system could also be used for studies of the Sun and nearby planets, and the very large radio antenna that would be needed could also be used for radio astronomical investigations. This is put into context by looking at the then state of our knowledge of the Earth’s ionosphere and the terrestrial planets as well as the then current situation with the new field of radio astronomy.