A review of radar astronomy — Part I

Radar astronomy evolved shortly after World War II when groups in Hungary and the United States independently detected radar echoes from the moon by utilizing radar equipment developed during the war. During the following ten years radar research was motivated primarily by the desire to use the moon as a passive reflector in communication systems. It was not until the middle 1950s that lunar radar experiments were conducted as a pure science.
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It was realized at that time that the distortions on the returned signal caused by the target and the medium could be analyzed in such a manner as to yield fundamental information on the nature of the lunar surface and cislunar space.