Harvest Moon: The US Army Signal Corps' Project Diana

Long before Artemis and the next lunar flights, there was the US Army Signal Corps' Project Diana. Project Diana has been preserved in history as the unofficial start of the Space Age, bouncing radar signals off the moon for the first time in early 1946. The post-war project was named after the Roman goddess of the moon, a naming tradition that would be used by later Army projects and space programs [1].

Cartoon from the Tennesseean newspaper (library.nashville.org)

Project Diana took place at Camp Evans Signal Laboratory at Fort Monmouth, located in Wall Township, New Jersey. Some of the lab's buildings were originally constructed in 1914 as receiving stations for the Marconi Wireless Telegraph Company. Its founder, Guglielmo Marconi, was the inventor of the wireless telegraph system. During World War II, the lab's main mission was to improve America's radar capabilities and experiment with captured German and Japanese radar technology (Makamson). In late 1943 it came under the direction of Lieutenant Colonel John H. DeWitt Jr., who came to the Army from Bell Laboratories [2]. The following year, a Nazi Germany V2 rocket became the first artificial object to enter outer space. After the use of atomic weapons brought about the end of the war in 1945, the US Pentagon began to worry about the possibility of an attack on the country by foreign long-range ballistic missiles. These weapons, which came to be known as intercontinental ballistic missiles, or ICBMs, dominated American military thinking in future decades.

Project Diana card for reception reports (rfcafe.com)

The Pentagon ordered the research team at Camp Evans to investigate if a weapon launched at the US could be tracked using radar. There were doubts about the real-world applicability of the team's calculations and experiments, as well as plenty of setbacks and malfunctions. Project Diana was not a top priority for the Department of Defense so funding was limited. Since they could not test their theory with actual weapons, they chose the next best target— the moon. The team modified the existing SCR-271 bedspring radar antenna and mounted an array atop the 100-foot tower. It provided 3,000 watts at 111.5 megahertz in quarter-second pulses. The dipole array antenna provided 24 dB of gain. There were only 40 minutes per day when the moon passed through the 15-degree-wide beam detectable by the array. Project Diana's team consisted of Chief Scientist E. King Stodola, Lt. Col. John Dewitt, Herbert Kauffman, Jacob Mofenson, Harold Webb, and famed mathematician Walter McAfee.

Project Diana staff (l-r): Mofenson, Webb, DeWitt, Stodola, and Kauffman

(US Army Communications Electronics Museum)

On Thursday, January 10, 1946 at 11:58 a.m. Lt. Col. DeWitt's team detected the first signals reflected back from the moon. These radio waves took 2.5 seconds to travel from Fort Monmouth to the Earth's only satellite and back, a technique they named "Moonbounce". It is known today as Earth-Moon-Earth communication, or EME, and is still used by HAM and amateur radio operators. It was repeated over the period of a few days and demonstrated for Pentagon officials, who were also interested in using this new technology to potentially eavesdrop on the nation's new enemy, the Soviet Union.

Although Project Diana had limited military potential, it was the birth of radar astronomy and the start of the Space Age. Most importantly, it proved radio communication could be conducted through Earth's ionosphere. The creation and future implementation of this technology was a crucial first step in further space exploration, including the development of satellites and eventually crewed spaceflight.

Project Diana's radar site at Camp Evans (infoage.org)

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[1] The most famous examples of the Greco-Roman naming tradition are Mercury, Gemini, Apollo, Jupiter, Atlas, and Titan.

[2] Bell Laboratories developed Telstar, the first active communications satellite, in 1962.

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Bibliography

• Deffree, Suzanne. “Project Diana Bounces Radio Waves off Moon, January 10, 1946.” EDN, 9 June 2020, https://www.edn.com/project-diana-bounces-radio-waves-off-moon-january-10-1946/.

• Makamson, Collin. “Project Diana: To the Moon and Back” The National WWII Museum | New Orleans, The National World War II Museum, 7 Jan. 2021, https://www.nationalww2museum.org/war/articles/project-diana-moon-and-soviet-union.

• Scott, Art. “InfoAge Science & History Museums.” InfoAge Science and History Museums, 2 Sept. 1998, https://infoage.org/history-ia/army-research/project-diana-january-10-1946/.