Radio telescope of Arecibo

The radio telescope of Arecibo is located at Arecibo, Puerto Rico on the northern side of the island. It is exploited by the Université Cornell with an agreement of coopeation with the the National Science Foundation. The observatory functions under the name National Astronomy and Ionosphere Center ( NAIC ) even if the two names are officially used.

The radio telescope is the largest simple telescope ever built. It planetary data and terrestrial Aéronomie, radioastronomic data-gathering radar for the world scientists. The use of the telescope is done after tender of proposal at an independent committee.

Even if it were used for various uses, it is used mainly for the observation of stellar objects.

General information

The telescope of Arecibo is characterized by its big size: the diameter of the principal antenna of 305 meters, is built inside the depression left by a collapse. The antenna is the largest curved antenna convergent of the world, which gives him the greatest capacity of collection of electromagnetic waves. The surface of the antenna is made of 38.778 perforated aluminum panels, each one measuring approximately 1 m out of 2 m, supported by a grid of steel wire ropes.

It is a spherical Antenne (in opposition to parabolic Aerial). This form comes from the method used to point the telescope. The antenna is fixed but the receiver positions in its focal point to intercept the considered signals of the various directions by spherical surface. The receiver is located on a platform of 900 tons suspended at 150 m above the antenna by 18 cables starting from three turns out of reinforced concrete, 110 m height one and two 80 height m others (the tops of the three turns are on the same level). The platform has a 93 m length revolving way, in the shape of arc, on which are mounted the reception antenna, secondary and tertiary reflectors. That makes it possible the telescope to observe any area of the sky in a cone of 40 degrees around the local zenith (between -1 and 38 degrees of variation). The localization of Puerto Rico close to the equator makes it possible Arecibo to observe all planets of the Solar system.

Design and architecture

The construction of the telescope of Arecibo was initiated by the professor William E. Gordon of the Cornell University, which intended to use it in the beginning to study the Ionosphère Earth. At the origin, reflectors parabolic fixed, pointing in a direction fixes with a tower of 150 m to carry the equipment to the hearth. This design would have had an interest very limited for other potential fields of research, such as the planetary science and the radioastronomy, which need to aim various positions in the sky and to follow these positions for one long period, whereas the Earth is in rotation. Ward Low of the Advanced Research Projects Agency (ARPA), pointed out this weak point and put Gordon in contact with the Air Force Cambridge Research Laboratory (AFCRL) in Boston, Massachusetts where a group directed by Phil Blacksmith worked on the spherical reflectors and another group studied the radio wave propagation in and through the upper atmosphere. The Cornell University proposed the project in the ARPA the summer 1958 and one contract was signed between the AFCRL and the University in November 1959. Construction began the summer 1960 and grand opening took place on November 1st, 1963.

The telescope underwent several modifications during its life. The first great modification took place in 1974 when a surface utmost precision was added to the reflectors current. In 1997, a screen on the ground was installed around the perimeter to make screen with the radiation on the ground and a more powerful transmitter was installed.

Discovered

The telescope of Arecibo made several important discoveries.

April 7th, 1964, shortly after her inauguration, the team of Gordon H. Pettengill used it to determine that the period of rotation of the planère Mercure was not 88 days, as what was thought, but of only 59 days.

In August 1989, the observatory made an image of an asteroid for the first time in the history: the asteroid (4769) Castalia.

The following year, the Polish astronomer Aleksander Wolszczan made the discovery of the Pulsar PSR B1257+12, which will lead it later to discover its two planets in orbit. They were the first planets extrasolaires never discovered.

Use

The telescope also had military uses of information, for example to locate the Soviet installations of radar, by detecting their signals rebounding on the the Moon.

Arecibo is the source data for the project SETI@home proposed by the laboratory of space sciences of the Université of Berkeley.

In 1974, an attempt was made to send a message towards other worlds. A message of 1.679 bits was transmitted starting from the radio telescope towards the globular cluster M13, which is at approximately 25.000 light-years. The model of 1 and 0 defines an image bitmap of 23 pixels by 73 which includes drawn numbers, catches, chemical formulas and a rough image of the telescope itself (For more information, to see the Message of Arecibo).

3 with the March 7th 2001, the observatory was used to observe the Astéroïde (29075) 1950 DA, considered as being the object nearest to the Earth.

Appearances with the cinema

The telescope appeared in film of James Bond GoldenEye , where Alec Trevelyan communicated with the Russian satellite which was to destroy London.

In the episode of X-Files entitled Small Men Green , Fox Mulder is sent to the observatory of Arecibo by a senator of the the United States because they were in contact with an extraterrestrial life. The observatory was to be destroyed by a group of government officials to prevent that the public discovers the truth.

It also appeared in the films Contact , The Arrival and Mutant the 1 .

Internal bonds

(4337) Arecibo

External bonds

naic.edu - Official site of the radio telescope of Arecibo
setiathome.ssl.berkeley.edu - Official site of the project SETI@home
IEEE History Center - IEEE Milestones: NAIC/Arecibo Radio telescope
Satellite image

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