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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Hubble telescope. History of invention and production
Directory / The history of technology, technology, objects around us The Hubble Space Telescope (HST; eng. Hubble Space Telescope, HST; observatory code "250") is an automatic observatory in orbit around the Earth, named after Edwin Hubble. The Hubble Telescope is a joint project between NASA and the European Space Agency; it is part of NASA's Large Observatories. Placing a telescope in space makes it possible to register electromagnetic radiation in the ranges in which the earth's atmosphere is opaque; primarily in the infrared range. Due to the absence of the influence of the atmosphere, the resolution of the telescope is 7-10 times greater than that of a similar telescope located on Earth.
The priority of making the telescope is still disputed. According to a number of documents, one of the first instruments was made in the Netherlands by Zachary Jansen in 1604 after the Italian model of 1590. Other eyewitness records report that the first spotting scopes were invented around 1605-1610 in Middelburg by spectacle maker John Lapree. In any case, already in 1608 telescopes were made by many masters. In particular, Jacob Metzius. In 1610, Galileo created a telescope with a magnification of 32 times! Astronomical research scientist brought him great fame. Impressed by the successes of Galileo, Johannes Kepler returned in 1610 to applied optics. He proposed a fundamentally new optical scheme of the spotting scope. Before that, only one combination of lenses was used in it - a series connection of a diverging (concave) lens as an objective and a collecting (convex) lens as an eyepiece. The Kepler tube had two convex lenses, which, in addition to a larger field of view, made it possible for the first time to obtain a direct image of the observed object. Such a telescope could serve as a sighting device, that is, from a purely observational instrument it also became a measuring one. And this greatly expanded the scope of its application. However, the first telescopes gave images noticeably distorted by various defects (aberrations). Scientists - who were then the main telescope builders - tried to eliminate them by increasing the focal length of the lens. So it was until 1668, when Isaac Newton first built an instrument of a completely new type - a reflecting telescope (mirror), devoid of the chromatic aberration inherent in lens devices (refractors). The lens was a concave metal mirror. The perfection of the image depended on the workmanship of the latter. Twenty-one years after Newton, the English astronomer and optician William Herschel polished a mirror with a diameter of 122 centimeters. At that time it was the world's greatest reflector. Realizing that increasing the size of telescopes is a direct path to new discoveries, astronomers from the world's leading observatories entered into a real competition. In 1917, the American D. Ritchie built a new reflector for the Mount Wilson Observatory; for many years it remained the largest in the world. Its 258-cm mirror weighed five tons with a total weight of one hundred tons. In 1931, the German optician B. Schmidt, and then his Soviet colleague D.D. Maksutov (1941) developed two design options for combined mirror-lens telescopes. Both instruments received worldwide recognition and began to bear the names of their creators. Maksutov introduced a corrective lens into an ordinary mirror telescope, which corrected the distortions introduced by a spherical mirror. Already the first such systems made it possible to obtain photographs of the starry sky of unique quality and to issue a fundamental astronomical publication - an atlas of nebulae. In the history of telescope construction, refractors "fought" with reflectors for a long time, until, finally, the latter won. The largest of them, with a six-meter main mirror made of glass-ceramic material - glass-ceramic, was installed in the Special Astrophysical Observatory of the Russian Academy of Sciences on Mount Semirodniki near the Zelenchukskaya station, in the North Caucasus. The processing of the seventy-ton mirror continued until the summer of 1974, and regular observations began in February 1976 - after a total of sixteen years of preparatory work. The grandiose 42-meter structure weighs 950 tons. This telescope "sees" celestial objects up to the 26th magnitude, located on the border of the observable universe. Back in the 1940s, astronomers realized that the electromagnetic radiation of space objects is by no means limited to the visible spectrum, but is distributed over almost all ranges - from radio waves to gamma rays, and that observation in new regions of the spectrum can bring valuable information that was previously completely inaccessible. The first in a series of "non-optical" instruments were radio telescopes, thanks to which, back in the same 1940s, radio galaxies were discovered that were invisible even to the best optical instruments of that time. The researchers immediately appreciated that, unlike the latest, new devices do not depend on the vagaries of the weather. As for the design, among radio telescopes, as in optical ones, reflectors reign. The mirror here is a metal mesh paraboloid, in the focus of which the antenna is installed. The signal induced in it is fed to the receiver for processing, and from it to the recording devices. The largest infrared telescope was built on Mauna Kea (Hawaii, USA) at an altitude of 4200 meters above sea level with a mirror with a diameter of 374 centimeters. It is so perfect that it can also be used for visual observations. Equipped with a computer control system, it can automatically aim at a given object and track it. On the left is the main mirror, on the right is the system node. And in 1985, at the Mauna Kea Observatory, work began on a ten-meter composite Keck reflector, including 36 autonomously controlled hexagonal mirrors with a diameter of 183 centimeters each. For a more accurate fixation of the mirrors and general focusing of the image, a special unloading device has been developed, which reduces stresses in the structural elements.
However, the possibilities of improving the characteristics of optical telescopes have not been exhausted. Electron photomultipliers began to be used, making it possible to increase the efficiency of observations by almost two orders of magnitude. Thus, the 508-cm Hale reflector equipped with them at the Mount Palomar Observatory (California, USA), built in 1948, has a resolution of a "simple" telescope with a mirror of 25,4 meters. Now it is the most efficient terrestrial optical instrument. For new information, telescopes went to near-Earth orbits. Thus, the Mir space station was equipped with the Kvant module with two special telescopes - ultraviolet and infrared. And the devices of the automatic orbital observatory "Astron" could observe space objects simultaneously in x-ray and ultraviolet rays. On April 24, 1990, with the launch of the Hubble Space Telescope, a truly golden age of astronomy began. NASA, together with the European Space Agency, began developing the space telescope project in the late 1970s. It was planned that this would be a space observatory, which would be visited every two to three years by ships from Earth for maintenance and troubleshooting. The telescope got its name in honor of one of the outstanding astronomers of the XNUMXth century, Edwin Hubble, a true classic of science. He left a grandiose legacy - an evolving world of galaxies, governed by the law of his name. Hubble has made such remarkable discoveries that they give the indisputable right to call Hubble the greatest astronomer since Copernicus. Edwin Hubble was born November 20, 1889. He spent his childhood in a strong friendly family, where eight children grew up. Edwin became interested in astronomy early, probably under the influence of his maternal grandfather, who built himself a small telescope. In 1906, Edwin graduated from high school, after which he entered the University of Chicago. The astronomer F.R. Multon, author of the well-known theory of the origin of the solar system. He had a great influence on the further choice of Hubble. After graduating from university, Hubble managed to get a Rhodes scholarship and go to England for three years to continue his education. However, instead of the natural sciences, he had to study law at Cambridge. In the summer of 1913, Edwin returned to his homeland, but he did not become a lawyer. Hubble strove for science and returned to the University of Chicago, where at the Yerkes Observatory, under the guidance of Professor Frost, he prepared a dissertation for a Ph.D. In the spring of 1917, when he was completing his dissertation, the United States entered the First World War. The young scientist declined the invitation and volunteered for the army. In the summer of 1919, Hubble was discharged and hurried to Pasadena to work at the new Mount Wilson Observatory. Hubble worked here until his death, with a four-year break during World War II. At the observatory, he began to study nebulae, focusing first on objects visible in the Milky Way band. The first thing Hubble did was to classify them. This classification continues to serve science, and all subsequent modifications of its essence have not been affected. Already one establishment of the true nature of the nebulae determined the place of Hubble in the history of astronomy. But an even more outstanding achievement fell to his lot - the discovery of the law of redshift. After the war, the observatory, where the astronomer returned, resumed the development of a two-hundred-inch (508-centimeter) telescope. Hubble chaired a committee to create advanced research plans for the new instrument, and was a member of the management committee of the combined Mount Wilson and Mount Palomar observatories. Hubble saw the main task of the observatory in solving the cosmological problem. "We can confidently predict," he said with conviction, "that the 200-incher will tell us whether the redshift should be considered evidence in favor of a rapidly expanding universe, or whether it is due to some new principle of nature." Hubble died of a stroke on September 28, 1953. There are no monuments to Hubble on Earth. No one even knows where he is buried, such was the will of his wife. A crater on the Moon, asteroid No. 2069 and a space telescope, the largest in the world, are named after him. The telescope weighing 11 tons, with a length of 13,1 meters and a reflector diameter of 240 centimeters, costs 1,2 billion dollars - more than one hundred million dollars per ton. According to specialists' calculations, Hubble will operate in orbit until 2005. The telescope is equipped with several scientific instruments. The wide-angle camera is designed to photograph the surfaces of planets and their satellites. The camera for dimly luminous objects amplifies a hundred thousand times the light falling on it. The spectrograph for this faint light analyzes the radiation and can reveal the chemical composition and temperature of whatever emitted it. The so-called Goddard spectrograph determines how an object that emits light moves. Hubble launched one of the shuttles into a 613-kilometer-high orbit in April 1990. The work of the telescope began with a failure. Two months after the launch, it became clear that the main mirror of the telescope with a diameter of two and a half meters deviates at its edges from the calculated size by several microns - a fiftieth of the thickness of a human hair. But this was enough to practically erase the work of thousands of people - the image was unclear and blurry.
To correct the consequences of aberration, complex corrective programs were created, and the image began to be corrected already on Earth using computers. But even in this form, the Hubble telescope made it possible to make discoveries: to detect black holes in the centers of galaxies, a new storm on Saturn, divergent rings around a supernova. Nevertheless, it was obvious that repairs were indispensable. It is impossible to change the mirror in space conditions, so it was decided to "put on glasses" on each of the instruments of the telescope: add small devices for correction. Two small mirrors corrected the lack of a large one. Early on the morning of December 2, 1993, seven astronauts set out on a space shuttle to repair the telescope. They returned eleven days later, having done everything that was planned, and setting a record for spacewalks - there were five of them. Four days later, scientists gathered in the data processing room of the Space Telescope Institute in Baltimore, Maryland, eagerly awaiting the first images from the corrected observatory. They appeared on the terminal screen at one in the morning, and the room was immediately filled with joyful cries - now the telescope was working at one hundred percent. And his capabilities are such that from any city in America he could distinguish two fireflies fluttering as far as Tokyo, if they were not closer than three meters from each other. During the years of its flight behind the clouds, the space observatory made several tens of thousands of revolutions around the Earth, "winding" billions of kilometers in the process. The Hubble telescope has already made it possible to observe more than eight thousand celestial objects. For comparison, about the same number of stars can be seen from Earth with the naked eye. His memory stores the "addresses" of fifteen million stars that he can explore. Two and a half trillion bytes of information collected by the telescope is stored on 375 optical disks. He allowed scientists from about forty countries to publish more than a thousand scientific papers. Thanks to the Hubble, discoveries were made that entered the history of astronomy and even in institute textbooks. It was possible to find out, for example, that black holes do exist and are usually located in the centers of galaxies. Or the fact that the primary stage of the birth of planets is the same for all stars, and the dark spot on Neptune does not stand still: it disappears in one hemisphere and appears in another. Another conclusion is that Jupiter's moon Europa has a thin oxygen atmosphere. Another discovery - a belt of hundreds of millions of comets surrounds the solar system. The telescope helped to find new satellites beyond the outer ring of Saturn, to make the first map of the surface of an asteroid flying near the Earth, and made it possible to detect helium left over from the time of the Big Bang in intergalactic space. "Hubble" made it possible to look into the most remote corners of space, to change our views on the earliest stages of the origin of the Universe. Hubble has discovered a new class of gravitational lenses that will be used as "telescopes" to explore the universe. With their help, astronomers can see how the process of star formation in the blue galaxy went then. The telescope helped scientists measure the rotational speed of the gaseous disk of the elliptical galaxy M87 in the constellation Virgo, fifty million light-years away from Earth. It turned out that it revolves around "something" with a mass of three billion solar masses. "If it's not a black hole, then I have no idea what it is," says Professor Ford of the Space Telescope Institute. "We absolutely did not expect to see a rotating spiral structure at the center of an elliptical galaxy." Black holes are very massive and incredibly dense objects. In recent decades, they have been talked about a lot, argued, searched for them, but only the Hubble telescope confirmed their existence. It has long been known that powerful optical and radio emission comes out of the center of the M87 galaxy. Only now, after the discovery of a rotating disk, it became clear that this black hole, sucking in matter, creates the effect of a "tornado" - a spinning vortex hundreds of light years in size. This stream is clearly visible in the picture. It was also possible to establish that the dust disk is heated to ten thousand degrees and its outer edges are spinning at a speed of more than five hundred kilometers per second. Giant black holes can eject particles accelerated to almost the speed of light into jets. From the images of the planets obtained by the telescope, it is just right to make a small exhibition. Thus, the telescope was the first to photograph the surface of Pluto with such a resolution that one could speak of a map of the planet. Until recently, the ninth planet of the solar system was hidden from the gaze of space explorers. This is a unique celestial body: it does not fit into any classifications. Pluto revolves around the Sun, but it is not classified as either a gas giant or a solid planet. It behaves like a comet, periodically losing its atmosphere, but it is not a comet. It may be the last remaining of the ice dwarfs that inhabited the solar system at the dawn of its formation. Only Triton - a satellite of Neptune - is suitable for him as a relative. "The results are simply fantastic," says American astronomer Marc Bue from Texas. "Hubble made Pluto a world with its mountains, depressions, and seasons from an obscure speck. I experienced a similar feeling when I looked at Mars through a telescope." Experts distinguish polar caps, bright moving spots and mysterious lines in the pictures. In their opinion, all this is either just snow or dirty snow, since Pluto is now in a position close to the Sun and there is a warm season, the snow is melting. From Earth, Pluto can barely be seen, and there has never been any talk of any of its surface. Scientists now conclude that Pluto is second only to Earth in terms of the variety of surface features in the solar system. Pluto is the only planet to which a spacecraft has not yet been sent, but after such discoveries of the Hubble telescope, a probe is already planned to be launched there. During the second "technical inspection" in February 1997, the telescope was replaced with a high-resolution spectrograph, a spectrograph of faint objects, a star-pointing device, a tape recorder for recording information, and solar battery electronics. There is no visible limit to the development of telescope construction in the foreseeable future. Apparently, the time is still very far away when astronomers will be able to "pump out" all the information contained in it from the radiation of stars and galaxies reaching us ... Author: Musskiy S.A.
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