India, Sept. 28 -- Way before we had "read receipts" to tell us when a text message was received, a US Army team got a very different kind of response from the moon. On January 10, 1946, a small group at Camp Evans, New Jersey, bounced a radio signal off the surface of the moon and waited about 2.5 seconds for it to return. According to the team's research paper, published in the Proceedings of the I.R.E. in 1949, that single successful echo was the beginning of an entirely new field of science. The project is named Diana, for the Roman goddess of the moon.

The story begins with fear, not curiosity. A year after Nazi Germany's V-2 rockets had made it to space in 1944, and around the time atomic weapons had been used in 1945, US military ...