What radio event did Project Diana accomplish for the first time ever?
First EME contact
Project Diana, named for the Roman moon goddess Diana was a project of the US Army Signal Corps.
From a laboratory at Camp Evans in New Jersey, a large transmitter, receiver and antenna array were constructed. The transmitter, a highly modified SCR-271 radar set from World War II, provided 3,000 watts at 111.5 MHz in 1/4 second pulses, and the antenna (a “bedspring” dipole array) provided 24 dB of gain.
All of this equipment was used to bounce radio signals off the moon and receive the reflected signals, today called EME (Earth-Moon-Earth).
Reflected signals were received about 2.5 seconds later, with the receiver compensating for Doppler shift of the reflected signal. About 40 minutes of observation was available on each pass as the moon transited the various lobes of the antenna pattern.
The first successful echo detection (or EME contact) came on January 10, 1946 at 11:58am local time.
Project Diana marked the birth of radar astronomy and helped make the space program possible. It was the first demonstration that artificially-created signals could penetrate the ionosphere, opening the possibility of radio communications beyond the earth for space probes and human explorers. It also established the practice of naming space projects after Roman gods, e.g., Mercury and Apollo.
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