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published in(发表于) 2014/7/27 17:34:29
Guizhou built the world’s largest radio telescope， which is equivalent to 25 football pitches

Caliber FAST up to 500 meters of weak electromagnetic waves can be observed from the edge of the universe, it will in the next 20-30 years of world class equipment status.

　　Super peep the universe "pot"

It is the world's largest ever pot. Weighing tens of thousands of tons, pot vent area roughly equal to the sum of the 25 standard football field; use it to cook up a pot full of rice, more than 7 billion people around the world get together and have enough for 3 days.

This one is located in Guizhou, China, still in the construction phase.

Of course, this is FAST by world scientists known as "pot" is not built for the Cook, it's a giant radio telescope. For most ordinary people, this is a strange term, but in astronomy, it already exists and is highly dependent on more than 80 years. Super FAST, is just what the lion's radio telescope ever built.

According to search, and observation of electromagnetic waves wavelength classification, telescope roughly can is divided into three big class: x ray telescope--for observation universe x ray, like famous of "Chang de pulled" space telescope; visible telescope--to visible for tool observation universe, most famous is great of "Hubble", and "Hubble" of succession who, and future years will launch of "Weber" space telescope; radio telescope--through capture and analysis space in the of radio to observation space, such as United States " Arecibo "radio telescope.

In broad perspective, in 2013, shoot photos, and found that the dark energy of the universe to the infancy of the Wilkinson microwave anisotropy probe (WMAP) are also radio telescopes. Prior to this, in the 1960 of the 20th century, astronomers using radio telescopes have made four significant discovery: pulsars, quasars, and the cosmic microwave background radiation, interstellar organic molecules.

　　God no, into the door

From the observed effects to consider, in order to avoid disturbance of the atmosphere, telescopes the best "place of residence" is the space. But compared with two other types of telescopes, radio telescopes on the same area in the collected electromagnetic energy of less (after some calculations, all the energy collected by radio telescopes around the world in 80 years have enough to turn a page of the book) and, therefore, it needs a larger area to gather information from space. That is why, when "Hubble" and "Chang de la" when you have to go to space, radio telescopes on ground only sigh helplessly as dust-now technology is not enough to reach dozens of meters diameter and few hundred meters large telescope to move up into the sky.

Fortunately, compared with the two other telescopes, telescope observations are larger wavelengths of electromagnetic waves, disturbance of the atmosphere is relatively small. On the ground, scientists need to do is to gather a large number of radio waves in order to increase the sensitivity of radio telescopes, and the only way to achieve this goal, is to increase the telescope's working area.

Before the FAST, the biggest radio telescope was mentioned "Arecibo", with a calibre of up to 350 meters, but "Arecibo" is a fixed telescope, you cannot adjust the telescope direction aim at a target, it can only scan the skies for a belt, and because the earth rotates, it cannot continuously observe the same goals. "Arecibo", the telescope deformation due to gravity and wind limitations, traditional adjustable maximum aperture of the telescope only 100 metres.

　Sword of 20 years

In 1995, the Beijing Observatory and more than more than 20 domestic colleges and institutes jointly set up China Promotion Committee for the large radio telescope, presented in Guizhou Karst topography, built 500-meter aperture spherical radio telescope FAST (Five-hundred-meter Aperture Spherical Radio Telescope) the concept of sites identified in qiannan autonomous prefecture, Guizhou province, Pingtang County g-town village of Jinke "Tai Wo Dang" depressions. FAST engineering pre-study which lasted for 13 years, was not officially approved until July 10, 2007. On March 25, 2011, FAST project started construction and is expected to completed in September 2016.

July 17, 2014, at 11 o'clock in the morning, FAST construction to install their first main cable, reflector is being implemented in the cable network installation works--this is the first step in installing the entire telescope mirror frame. Due to the large mirror too (sum of area up to 30 standard football fields), you must have a carry the mirror's frame, which consists of ultra-high fatigue resistance, reinforced structure as scaffolding for a cable network-the cable network, reached a total weight of more than 1300 tons. All the cable-net structures have to be assembled at high altitude, entire cable network installation work is expected to take six months.

"Hubble", "Chang de la" Space Telescope uses gyroscopes to control a telescope lens, FAST, lightweight cable electric drive will use a robot control, pulling 500-meter aperture, tons of telescope mirror, realize the orientation of the camera--that can make the telescope to work around the clock, and could be observed under controlled conditions in any orientation in space.

Overlooking the edge of the universe

In 1960, Martin Ryle of the Cavendish laboratory of Cambridge University using the interference principle "Aperture synthesis radio telescope", which greatly improves the resolution of radio telescopes. The basic principle is: apart of two radio telescopes receiving radio waves from the same object, the beams interfere, its highest equivalent resolution is equal to a diameter equivalent to the distance between the two places single-aperture radio telescope. At present, the field of radio astronomy have utilized this technology radio telescopes all over the world together, won the order of equivalent diameter is equivalent to Earth's diameter radio telescopes. Ryle for this invention was awarded the 1974 Nobel Prize in physics.

Perhaps some people may ask: since this technology is allowing scientists to have the "equivalent diameter is equivalent to Earth's diameter-class" radio telescope, build calibre and just 500 metres from the FAST or what's the point?

Friends raised the issue of confusing the two concepts, that is the telescope's "sensitivity" and "resolution". "Aperture synthesis radio telescope" technology can only improve the resolution of radio telescopes, but if the space between the two radio telescope sensitivity is not high enough, then this technique is of no use--it seems like police, wanted by the national network can quickly find criminals, but who are determined before the prisoners, still relies on a particular police station-its detection abilities like the sensitivity of radio telescopes. So far, the only way to improve the sensitivity of radio telescopes, is to increase collection of cosmic radio waves of the mirror area. Theoretically, with a calibre of up to 500 meters of the FAST is observed from the edge of the universe of weak electromagnetic waves. Because of this, Chinese scientists say, the world's largest single-aperture telescope, FAST in the next 20-30 years of world class equipment status.

The Beijing News contributing writer/journalist (science writer)

-Beijing News reporter Guo Tieliu photography

(Original title: the accommodates universe a "pot")

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