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Project Diana, named for the Roman moon goddess Diana, was an experimental project of the US Army Signal Corps in 1946 to bounce radar signals off the Moon and receive the reflected signals. [1] This was the first experiment in radar astronomy and the first active attempt to probe another celestial body. It was the inspiration for later Earth–Moon–Earth communication (EME) techniques.
Following the end of World War II, Col. John H. DeWitt Jr., Director of the Evans Signal Laboratory at Camp Evans (part of Fort Monmouth), in Wall Township, New Jersey, 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, who made the required mathematical calculations. [2] [3] [4]
On the Laboratory site, a large transmitter, receiver and antenna array were constructed for this purpose. [1] The transmitter, a highly modified SCR-271 radar set from World War II, [1] provided 3 kilowatts (later upgraded to 50 kilowatts) at 111.5 MHz in 1⁄4-second pulses, applied to the antenna, a "bedspring" reflective array antenna composed of an 8x8 array of half wave dipoles 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 768,000-kilometre (477,000 mi) round-trip journey from the Earth to the Moon and back. [1] 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. [1] 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 on 10 January 1946 at 11:58am local time by Harold Webb and Herbert Kauffman. [5]
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, [1] 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.
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 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 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 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 satellites in the early 1960s. Since then it has been used by amateur radio operators.
Today, the Project Diana site is part of the Camp Evans Historic District, InfoAge Science History Learning Center and Museum, and is maintained by the Ocean-Monmouth Amateur Radio Club. [6] The antenna array was removed earlier and is now presumably lost.
Radar is a system that uses radio waves to determine the distance (ranging), direction, and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain.
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. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit 22,300 miles (35,900 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night.
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observations have identified a number of different sources of radio emission. These include stars and galaxies, as well as entirely new classes of objects, such as radio galaxies, quasars, pulsars, and masers. The discovery of the cosmic microwave background radiation, regarded as evidence for the Big Bang theory, was made through radio astronomy.
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters. Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or "skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting stations (3.95–25.82 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.
TV DX and FM DX is the active search for distant radio or television stations received during unusual atmospheric conditions. The term DX is an old telegraphic term meaning "long distance."
In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave propagation can be used to communicate beyond the horizon, at intercontinental distances. It is mostly used in the shortwave frequency bands.
A directional antenna or beam antenna is an antenna which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain direction is desired, or in receiving antennas receive radio waves from one specific direction only. This can increase the power transmitted to receivers in that direction, or reduce interference from unwanted sources. This contrasts with omnidirectional antennas such as dipole antennas which radiate radio waves over a wide angle, or receive from a wide angle.
Project Echo was the first passive communications satellite experiment. Each of the two American spacecraft, launched in 1960 and 1964, were metalized balloon satellites acting as passive reflectors of microwave signals. Communication signals were transmitted from one location on Earth and bounced off the surface of the satellite to another Earth location.
The Communication Moon Relay project was a telecommunication project carried out by the United States Navy. Its objective was to develop a secure and reliable method of wireless communication by using the Moon as a natural communications satellite — a technique known as Earth–Moon–Earth communication (EME). Most of the project's work took place during the 1950s at the United States Naval Research Laboratory. Operation Moon Relay was spun off from a classified military espionage program known as Passive Moon Relay (PAMOR), which sought to eavesdrop on Soviet military radar signals reflected from the Moon.
Earth–Moon–Earth communication (EME), also known as Moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver.
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 laboratories of the United States Army. It was designated a National Historic Landmark District in 2012, in recognition of the site's long role in the development of modern civilian and military electronic communications.
The Dwingeloo Radio Observatory is a single-dish radio telescope near the village of Dwingeloo in the northeastern Netherlands. Construction started in 1954, and the telescope was completed in 1956. The radio telescope has a diameter of 25 m. At the time of completion it was the largest radio telescope in the world, but it was overtaken in 1957 by the 250 foot (76 m) Lovell Telescope.
Haystack Observatory is a multidisciplinary radio science center, ionospheric observatory, and astronomical microwave observatory owned by Massachusetts Institute of Technology (MIT). It is in Westford, Massachusetts, in the United States, about 45 kilometers (28 mi) northwest of Boston. The observatory was built by MIT's Lincoln Laboratory for the United States Air Force and was called the Haystack Microwave Research Facility. Construction began in 1960, and the antenna began operating in 1964. In 1970 the facility was transferred to MIT, which then formed the Northeast Radio Observatory Corporation (NEROC) with other universities to operate the site as the Haystack Observatory. As of January 2012, a total of nine institutions participated in NEROC.
Walter Samuel McAfee was an American scientist and astronomer, notable for participating in the world's first lunar radar echo experiments with Project Diana.
John H. DeWitt Jr. 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 Project Diana.
The Communications-Electronics Command (CECOM) is a Life Cycle Management Command (LCMC) of the United States Army based at Aberdeen Proving Ground, Maryland, United States. It is one of four such commands under the Army Materiel Command (AMC), and is the Army's provider and maintainer of Command, Control, Communications, Computers, Cyber, Intelligence, Surveillance and Reconnaissance (C5ISR) capabilities.
Edwin King Stodola was an American radio engineer.
Harold Donivan Webb was a physicist and a professor of electrical engineering at the University of Illinois, Urbana-Champaign. In 1946, he was one of the members of the US Army Signal Corps Project Diana team at Camp Evans, New Jersey, that was the first to bounce radar signals off of the Moon. Dr. Webb continued research on ionosphere, moon reflection and radio astronomy at the University of Illinois. One of his daughters, Diana, was named after the Project.
Queqiao relay satellite (Chinese: 鹊桥号中继卫星; pinyin: Quèqiáo hào zhōngjì wèixīng; lit. 'Magpie Bridge relay satellite'), is the first of the pair of communications relay and radio astronomy satellites for the Chinese Lunar Exploration Program. The China National Space Administration (CNSA) launched the Queqiao relay satellite on 20 May 2018 to a halo orbit around the Earth–Moon L2 Lagrangian point Queqiao is the first ever communication relay and radio astronomy satellite at this location.