US Army's Moon Bounce: Birth of Radar Astronomy

On January 10, 1946, a US Army team at Camp Evans, New Jersey, successfully bounced a radio signal off the moon, a feat that took approximately 2.5 seconds to confirm. This experiment, codenamed Project Diana, was initially driven by concerns over intercontinental ballistic missiles and the ability of radar to track them through the ionosphere.

Lacking a suitable missile for practice, the team, led by Lt. Col. John H. DeWitt Jr. and chief scientist E. King Stodola, chose the moon as their target. After overcoming equipment and timing challenges, their successful echo proved radio waves could penetrate the ionosphere. This breakthrough unexpectedly initiated the field of planetary radar astronomy.

While the original military objective of tracking missiles wasn't realized, the scientific implications were profound. This achievement, a decade before satellites, demonstrated humans could send signals into space and receive replies. Today, amateur radio operators still utilize the Earth-Moon-Earth communication method pioneered by Project Diana.