Project Diana
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Project Diana, named for the
Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...
moon goddess A lunar deity or moon deity is a deity who represents the Moon, or an aspect of it. These deities can have a variety of functions and traditions depending upon the culture, but they are often related. Lunar deities and Moon worship can be found ...
Diana, was an experimental project of the
US Army Signal Corps ) , colors = Orange and white , colors_label = Corps colors , march = , mascot = , equipment = , equipment_label = ...
in 1946 to bounce
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
signals off the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
and receive the reflected signals. This was the first experiment in
radar astronomy Radar astronomy is a technique of observing nearby astronomical objects by reflecting radio waves or microwaves off target objects and analyzing their reflections. Radar astronomy differs from ''radio astronomy'' in that the latter is a passive o ...
and the first active attempt to probe another
celestial body An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical object, physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''bod ...
. It was the inspiration for later EME (Earth-Moon-Earth) communication techniques.


History

Following the end of World War II, Col.
John H. DeWitt Jr. John H. DeWitt Jr. (February 20, 1906 – January 25, 1999) was an American pioneer in radio broadcasting, radar astronomy and photometry. He observed the first successful reception of radio echoes off the moon on January 10, 1946, as part of Proj ...
, Director of the Evans Signal Laboratory at
Camp Evans Camp Evans Historic District is an area of the Camp Evans Formerly Used Defense Site in Wall Township, New Jersey. The site of the military installation () is noted for a 1914 transatlantic radio receiver and various World War II/Cold War labo ...
(part of
Fort Monmouth Fort Monmouth is a former installation of the Department of the Army in Monmouth County, New Jersey. The post is surrounded by the communities of Eatontown, Tinton Falls and Oceanport, New Jersey, and is located about from the Atlantic Ocean. Th ...
), in
Wall Township, New Jersey Wall Township is a township in Monmouth County, New Jersey, United States. It is located in the New York Metropolitan Area and is a bedroom community of New York. As of the 2010 United States Census, the township's population was 26,164, refle ...
, was directed by the Pentagon to determine whether the ionosphere could be penetrated by radar, in order to detect and track enemy ballistic missiles that might enter the ionosphere. He decided to address this charge by attempting to bounce radar waves off the moon. For this task he assembled a team of engineers that included Chief Scientist E. King Stodola, Herbert Kauffman, Jacob Mofenson, and Harold Webb. Input from other Camp Evans units was sought on various issues, including most notably the mathematician
Walter McAfee Walter Samuel McAfee (September 2, 1914 – February 18, 1995) was an American scientist and astronomer, notable for participating in the world's first lunar radar echo experiments with Project Diana. Personal life McAfee was born in Ore Cit ...
, who made the required mathematical calculations. On the Laboratory site, a large
transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...
, receiver and
antenna array An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. The individual antennas (called ''elements'') are usually connected to a single receiver ...
were constructed for this purpose. The transmitter, a highly modified SCR-271
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
set from
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, provided 3
kilowatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...
s (later upgraded to 50 kilowatts) at 111.5
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...
in -second pulses, applied to the antenna, a "bedspring"
reflective array antenna In telecommunications and radar, a reflective array antenna is a class of directive antennas in which multiple driven elements are mounted in front of a flat surface designed to reflect the radio waves in a desired direction. They are a type o ...
composed of an 8x8 array of
half wave dipole In radio and telecommunications a dipole antenna or doublet is the simplest and most widely used class of antenna. The dipole is any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole wi ...
s and reflectors that provided 24 dB of gain. Return signals were received about 2.5 seconds later, the time required for the radio waves to make the round-trip journey from the Earth to the Moon and back. The receiver had to compensate for the
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
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 An azimuth (; from ar, اَلسُّمُوت, as-sumūt, the directions) is an angular measurement in a spherical coordinate system. More specifically, it is the horizontal angle from a cardinal direction, most commonly north. Mathematicall ...
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 The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...
angle was horizontal. About 40 minutes of observation was available on each pass as the Moon transited the various lobes of the
antenna pattern In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the ''directional'' (angular) dependence of the strength of the radio waves from the antenna or other source.Constantine A. Balanis: “A ...
. The first successful echo detection came on 10 January 1946 at 11:58am local time by Harold Webb and Herbert Kauffman. Project Diana marked the birth of
radar astronomy Radar astronomy is a technique of observing nearby astronomical objects by reflecting radio waves or microwaves off target objects and analyzing their reflections. Radar astronomy differs from ''radio astronomy'' in that the latter is a passive o ...
later used to map Venus and other nearby planets, and was a necessary precursor to the
US space program The space policy of the United States includes both the making of space policy through the legislative process, and the implementation of that policy in the United States' civilian and military space programs through regulatory agencies. The early ...
. It was the first demonstration that terrestrial radio signals could penetrate the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
, opening the possibility of radio communications beyond the earth for
space probes Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...
and human explorers. It also established the practice of naming space projects after Roman gods, e.g.,
Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
and
Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...
. Project Diana demonstrated the feasibility of using the Moon as a passive reflector to transmit radio signals from one point on the Earth to the other, around the curve of the Earth. This Earth-Moon-Earth (EME) or "moonbounce" path has been used in a few communication systems. One of the first was the secret US
military espionage Military intelligence is a military discipline that uses information collection and analysis approaches to provide guidance and direction to assist commanders in their decisions. This aim is achieved by providing an assessment of data from a ...
PAMOR (Passive Moon Relay) program in 1950, which sought to eavesdrop on Soviet Russian military radio communication by picking up stray signals reflected from the Moon. The return signals were extremely faint, and the US began secret construction of the largest
parabolic antenna A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or pa ...
in the world at Sugar Grove, West Virginia, until the project was abandoned in 1962 as too expensive. A more successful spinoff was the US Navy
Communication Moon Relay The Communication Moon Relay project (also known as simply Moon Relay, or, alternatively, Operation Moon Bounce) was a telecommunication project carried out by the United States Navy. Its objective was to develop a secure and reliable method of wi ...
or Operation Moonbounce communication system, which used the EME path for US military communication. In January, 1960 the system was inaugurated with a lunar relay link between Hawaii and Washington DC. Moonbounce communication was abandoned by the military with the advent of
communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...
s in the early 1960s. Since then it has been used by
amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...
operators. Today, the Project Diana site is part of the
Camp Evans Historic District Camp Evans Historic District is an area of the Camp Evans Formerly Used Defense Site in Wall Township, New Jersey. The site of the military installation () is noted for a 1914 transatlantic radio receiver and various World War II/Cold War lab ...
, InfoAge Science History Learning Center and Museum, and is maintained by the Ocean-Monmouth Amateur Radio Club. The antenna array was removed earlier and is now presumably lost.


References


Radar Echoes From the Moon
by Jack Mofenson of the Evans Signal Laboratory, Belmar N.J., January 1946.
IEEE Global History Network
* Butrica, Andrew J

(NASA SP4218, 1996).


Further reading

* * {{cite book , last1=Sullivan , first1=Woodruff T. , title=Cosmic Noise - A History of Early Radio Astronomy , date=2009 , publisher=Cambridge University Press , location=Cambridge , isbn=978-0-521-76524-4 , pages=264-271 1946 in science 1946 in the United States Radio technology Monmouth County, New Jersey United States Army projects