Also called
Earth-Moon-Earth (EME), the technique of using the
moon as a
passive radio signal reflector. High-powered signals are transmitted from
antennas pointed at
the moon, which acts as a giant
mirror in the
sky, bouncing the radio waves back to listeners on
Earth.
First done in 1946 by John H. DeWitt Jr. as he was working on the Pentagon's Project Diana. Ham radio signals were first bounced off the moon in 1953. Today, this is commonplace.