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1946 – The United States Army Signal Corps successfully conducts Project Diana, bouncing radio waves off the moon and receiving the reflected signals.
This was the first experiment in radar astronomy and the first attempt to actively probe another celestial body. It was the inspiration for later EME (Earth-Moon-Earth) communication techniques.
At a laboratory at Camp Evans (part of Fort Monmouth), in Wall Township, New Jersey, a large transmitter, receiver and antenna array were constructed for this purpose. 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, applied to the antenna, a “bedspring” reflective array antenna composed of an 8×8 array of half wave dipoles in front of a reflector which provided 24 dB of gain. Reflected signals were received about 2.5 seconds later, the time required for the radio waves to make the 477,000 mile round-trip journey from the Earth to the Moon and back.
The receiver had to compensate for the Doppler shift in frequency of the reflected signal due to the Moon’s orbital motion relative to the Earth’s surface, which was different each day, so this motion had to be carefully calculated for each trial. The antenna could be rotated in azimuth only, so the attempt could be made only as the moon passed through the 15 degree wide beam at moonrise and moonset, as the antenna’s elevation angle was horizontal. 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 came at 11:58am local time by John H. DeWitt and his chief scientist E. King Stodola. Project Diana marked the birth of radar astronomy later used to map Venus and other nearby planets, and was a necessary precursor to the US space program. It was the first demonstration that terrestrial radio 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.
http://thisdayinusmilhist.wordpress.com/2014/01/10/january-10/
This was the first experiment in radar astronomy and the first attempt to actively probe another celestial body. It was the inspiration for later EME (Earth-Moon-Earth) communication techniques.
At a laboratory at Camp Evans (part of Fort Monmouth), in Wall Township, New Jersey, a large transmitter, receiver and antenna array were constructed for this purpose. 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, applied to the antenna, a “bedspring” reflective array antenna composed of an 8×8 array of half wave dipoles in front of a reflector which provided 24 dB of gain. Reflected signals were received about 2.5 seconds later, the time required for the radio waves to make the 477,000 mile round-trip journey from the Earth to the Moon and back.
The receiver had to compensate for the Doppler shift in frequency of the reflected signal due to the Moon’s orbital motion relative to the Earth’s surface, which was different each day, so this motion had to be carefully calculated for each trial. The antenna could be rotated in azimuth only, so the attempt could be made only as the moon passed through the 15 degree wide beam at moonrise and moonset, as the antenna’s elevation angle was horizontal. 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 came at 11:58am local time by John H. DeWitt and his chief scientist E. King Stodola. Project Diana marked the birth of radar astronomy later used to map Venus and other nearby planets, and was a necessary precursor to the US space program. It was the first demonstration that terrestrial radio 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.
http://thisdayinusmilhist.wordpress.com/2014/01/10/january-10/
Signal Corps
NASA
Military History
Posted 10 y ago
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MSG (Join to see), I was Signal Corps officer for 24 years. Bad news for me was the best I could remember was "push to talk"! Thanks!
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