meter telescope. Where are the largest telescopes on Earth located? The largest telescopes: the experience of creation and use
10 largest telescopes
Far from the lights and noise of civilization, on the tops of mountains and in deserted deserts, titans live, whose multi-meter eyes are always turned to the stars.
We have selected 10 largest ground-based telescopes: some have been contemplating space for many years, others have yet to see the “first light”.
10Large Synoptic Survey Telescope
Main mirror diameter: 8.4 meters
Location: Chile, the peak of Mount Sero Pachon, 2682 meters above sea level
Type: reflector, optical
Although LSST will be located in Chile, this is a US project and its construction is entirely financed by the Americans, including Bill Gates (personally invested $10 million of the required $400).
The purpose of the telescope is to photograph the entire available night sky every few nights, for this the device is equipped with a 3.2 gigapixel camera. LSST stands out with a very wide viewing angle of 3.5 degrees (for comparison, the Moon and Sun, as seen from Earth, occupy only 0.5 degrees). Such possibilities are explained not only by the impressive diameter of the main mirror, but also by the unique design: instead of two standard mirrors, LSST uses three.
Among the scientific goals of the project are the search for manifestations of dark matter and dark energy, the mapping of the Milky Way, the detection of short-term events such as nova or supernova explosions, as well as the registration of small objects. solar system like asteroids and comets, in particular, near the Earth and in the Kuiper Belt.
The LSST is expected to see its “first light” (a common Western term for when the telescope is first used for its intended purpose) in 2020. On the this moment construction is underway, the device will be fully operational in 2022.
Large Synoptic Survey Telescope concept
9South African Large Telescope
Main mirror diameter: 11 x 9.8 meters
Location: South Africa, hilltop near the settlement of Sutherland, 1798 meters above sea level
Type: reflector, optical
The largest optical telescope in the southern hemisphere is located in South Africa, in a semi-desert area near the city of Sutherland. A third of the $36 million needed to build the telescope came from the South African government; the rest is divided between Poland, Germany, Great Britain, the USA and New Zealand.
SALT took his first picture in 2005, shortly after construction was completed. Its design is rather non-standard for optical telescopes, but it is widespread among the latest generation of "very large telescopes": the main mirror is not one and consists of 91 hexagonal mirrors with a diameter of 1 meter, the angle of inclination of each of which can be adjusted to achieve a certain visibility.
Designed for visual and spectrometric analysis of radiation from astronomical objects inaccessible to telescopes of the northern hemisphere. Employees of SALT are engaged in observations of quasars, nearby and distant galaxies, and also follow the evolution of stars.
There is a similar telescope in the States, it is called the Hobby-Eberly Telescope and is located in Texas, in the town of Fort Davis. Both the diameter of the mirror and its technology are almost identical to SALT.
South African Large Telescope
8. Keck I and Keck II
Main mirror diameter: 10 meters (both)
Location: USA, Hawaii, Mauna Kea, 4145 meters above sea level
Type: reflector, optical
Both of these American telescopes are connected into one system (astronomical interferometer) and can work together to create a single image. The unique location of the telescopes in one of the best places on Earth in terms of astroclimate (the degree to which the atmosphere interferes with the quality of astronomical observations) has made Keck one of the most efficient observatories in history.
The main mirrors of Keck I and Keck II are identical to each other and are similar in structure to the SALT telescope: they consist of 36 hexagonal moving elements. The equipment of the observatory makes it possible to observe the sky not only in the optical but also in the near infrared range.
In addition to the bulk of the widest range of research, Keck is currently one of the most effective ground-based tools in the search for exoplanets.
Keck at sunset
7. Gran Telescopio Canarias
Main mirror diameter: 10.4 meters
Location: Spain, Canary Islands, La Palma island, 2267 meters above sea level
Type: reflector, optical
The construction of the GTC ended in 2009, at the same time the observatory was officially opened. Even the king of Spain, Juan Carlos I, came to the ceremony. In total, 130 million euros were spent on the project: 90% was financed by Spain, and the remaining 10% was equally divided by Mexico and the University of Florida.
The telescope is capable of observing stars in the optical and mid-infrared range, has CanariCam and Osiris instruments, which allow the GTC to conduct spectrometric, polarimetric and coronographic studies of astronomical objects.
Gran Telescopio Camarias
6. Arecibo Observatory
Main mirror diameter: 304.8 meters
Location: Puerto Rico, Arecibo, 497 meters above sea level
Type: reflector, radio telescope
One of the most recognizable telescopes in the world, the Arecibo radio telescope has been caught on camera on numerous occasions: for example, the observatory was featured as the site of the final confrontation between James Bond and his antagonist in the movie GoldenEye, as well as in the sci-fi adaptation of Carl's novel Sagan "Contact".
This radio telescope has even made its way into video games - in particular, in one of the Battlefield 4 multiplayer maps called Rogue Transmission, a military clash between the two sides takes place just around a structure completely copied from Arecibo.
Arecibo looks really unusual: a giant telescope dish with a diameter of almost a third of a kilometer is placed in a natural karst funnel surrounded by jungle and covered with aluminum. A movable antenna feed is suspended above it, supported by 18 cables from three high towers along the edges of the reflector dish. The giant design allows Arecibo to catch electromagnetic radiation of a relatively large range - with a wavelength from 3 cm to 1 m.
Introduced back in the 60s, this radio telescope has been used in countless studies and managed to make a number of significant discoveries (like the first asteroid 4769 Castalia discovered by the telescope). Once Arecibo even provided scientists Nobel Prize: Hulse and Taylor were awarded in 1974 for the first ever discovery of a pulsar in a binary star system (PSR B1913+16).
In the late 1990s, the observatory also began to be used as one of the instruments of the US SETI project to search for extraterrestrial life.
Arecibo Observatory
5. Atacama Large Millimeter Array
Main mirror diameter: 12 and 7 meters
Location: Chile, Atacama Desert, 5058 meters above sea level
Type: radio interferometer
At the moment, this astronomical interferometer of 66 radio telescopes of 12 and 7 meters in diameter is the most expensive operating ground-based telescope. The US, Japan, Taiwan, Canada, Europe and, of course, Chile spent about $1.4 billion on it.
Since the purpose of ALMA is to study millimeter and submillimeter waves, the most favorable for such an apparatus is a dry and high-mountain climate; this explains the location of all six and a half dozen telescopes on the desert Chilean plateau 5 km above sea level.
The telescopes were delivered gradually, with the first radio antenna operational in 2008 and the last one in March 2013, when ALMA was officially launched to full capacity.
The main scientific goal of the giant interferometer is to study the evolution of the cosmos at the earliest stages of the development of the Universe; in particular, the birth and further dynamics of the first stars.
Radio telescopes of the ALMA system
4Giant Magellan Telescope
Main mirror diameter: 25.4 meters
Location: Chile, Las Campanas Observatory, 2516 meters above sea level
Type: reflector, optical
Far southwest of ALMA, in the same Atacama desert, another large telescope is under construction, a US and Australian project, the GMT. The main mirror will consist of one central and six symmetrically surrounding and slightly curved segments, forming a single reflector with a diameter of more than 25 meters. In addition to a huge reflector, the telescope will be equipped with the latest adaptive optics, which will make it possible to eliminate the distortions created by the atmosphere during observations as much as possible.
Scientists hope these factors will allow the GMT to capture images 10 times sharper than Hubble's, and probably even better than its long-awaited successor, the James Webb Space Telescope.
Among the scientific goals of GMT is a very wide range of research - the search for and images of exoplanets, the study of planetary, stellar and galactic evolution, the study of black holes, manifestations of dark energy, as well as the observation of the very first generation of galaxies. The operating range of the telescope in connection with the stated goals is optical, near and mid-infrared.
All work is expected to be completed by 2020, however, it is stated that GMT can see the "first light" already with 4 mirrors, as soon as they are introduced into the design. At the moment, work is underway to create the fourth mirror.
Giant Magellan Telescope Concept
3. Thirty Meter Telescope
Main mirror diameter: 30 meters
Location: USA, Hawaii, Mauna Kea, 4050 meters above sea level
Type: reflector, optical
The TMT is similar in purpose and performance to the GMT and the Hawaiian Keck telescopes. It is on the success of Keck that the larger TMT is based with the same technology of the main mirror divided into many hexagonal elements (only this time its diameter is three times larger), and the stated research goals of the project almost completely coincide with the tasks of the GMT, up to photographing the earliest galaxies almost at the edge of the universe.
The media name the different cost of the project, it varies from 900 million to 1.3 billion dollars. It is known that India and China have expressed their desire to participate in TMT, which agree to take on part of the financial obligations.
At the moment, a place has been chosen for construction, but there is still opposition from some forces in the administration of Hawaii. Mauna Kea is a sacred place for native Hawaiians, and many among them are strongly opposed to the construction of a super-large telescope.
It is assumed that all administrative problems will be resolved very soon, and it is planned to complete the construction around 2022.
Thirty Meter Telescope Concept
2. Square Kilometer Array
Main mirror diameter: 200 or 90 meters
Location: Australia and South Africa
Type: radio interferometer
If this interferometer is built, it will become 50 times more powerful astronomical instrument than the Earth's largest radio telescopes. The fact is that with its antennas, SKA must cover an area of \u200b\u200babout 1 square kilometer, which will provide it with unprecedented sensitivity.
In terms of structure, SKA is very similar to the ALMA project, however, in terms of dimensions it will significantly exceed its Chilean counterpart. At the moment, there are two formulas: either build 30 radio telescopes with antennas of 200 meters, or 150 with a diameter of 90 meters. One way or another, the length on which the telescopes will be placed will be, according to the plans of scientists, 3000 km.
To choose the country where the telescope will be built, a kind of competition was held. Australia and South Africa reached the “final”, and in 2012 a special commission announced its decision: the antennas will be distributed between Africa and Australia in a common system, that is, the SKA will be located on the territory of both countries.
The declared cost of the megaproject is $2 billion. The amount is divided among a number of countries: the UK, Germany, China, Australia, New Zealand, the Netherlands, South Africa, Italy, Canada and even Sweden. Construction is expected to be fully completed by 2020.
Artistic depiction of the 5 km SKA core
1. European Extremely Large Telescope
Main mirror diameter: 39.3 meters
Location: Chile, Cerro Armazones, 3060 meters
Type: reflector, optical
For a couple of years, perhaps. However, by 2025, a telescope will reach its full capacity, which will surpass TMT by a whole dozen meters and which, unlike the Hawaiian project, is already under construction. This is the undisputed leader of the latest generation of large telescopes, the European Very Large Telescope, or E-ELT.
Its main almost 40-meter mirror will consist of 798 moving elements with a diameter of 1.45 meters. This, along with modern system Adaptive optics will make the telescope so powerful that, according to scientists, it will not only be able to find planets similar to Earth in size, but will also be able to study the composition of their atmosphere with the help of a spectrograph, which opens up completely new perspectives in the study of planets outside the solar system.
In addition to the search for exoplanets, E-ELT will study the early stages of the development of the cosmos, try to measure the exact acceleration of the expansion of the Universe, check physical constants for, in fact, constancy over time; also this telescope will allow scientists to dive deeper than ever into the processes of planet formation and their primary chemical composition in search of water and organics - that is, E-ELT will help answer a number of fundamental questions of science, including those that affect the origin of life.
The cost of the telescope announced by representatives of the European Southern Observatory (the authors of the project) is 1 billion euros.
European Extremely Large Telescope Concept
Size comparison of E-ELT and Egyptian pyramids
Hello comrades. Something I'll tell you mostly spent objects, but garbage cans. Let's visit an active object - a real astrophysical observatory with a huge telescope.
So, here it is, a special astrophysical observatory Russian Academy sciences, known as object code 115.
It is located in the North Caucasus at the foot of Mount Pastukhovaya in the Zelenchuksky district of the Karachay-Cherkess Republic of Russia (the village of Nizhny Arkhyz and the village of Zelenchukskaya). At present, the observatory is the largest Russian astronomical center for ground-based observations of the Universe, which has large telescopes: a six-meter BTA optical reflector and the RATAN-600 ring radio telescope. Founded in June 1966. 
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With this gantry crane, the observatory was built.
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For more details, you can read http://www.sao.ru/hq/sekbta/40_SAO/SAO_40/SAO_40.htm here. 
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The observatory was created as a center for collective use to ensure the operation of the BTA optical telescope ( Big Telescope Azimuthal) with a mirror diameter of 6 meters and the RATAN-600 radio telescope with a ring antenna diameter of 600 meters, then the world's largest astronomical instruments. They were put into operation in 1975-1977 and are designed to study objects of near and far space using ground-based astronomy methods. 
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Looking at this futuristic door, you just want to go inside and feel all the power. 
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Here we are inside. 
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Before us is the old control panel. Apparently it doesn't work. 
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And here is the most interesting. BTA - "large azimuthal telescope". This marvel has been the largest telescope in the world since 1975, when it surpassed the Palomar Observatory's 5-meter Hale telescope, until 1993, when the Keck telescope with a 10-meter segmented mirror became operational.
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Yes, 
this Kek.
BTA is a reflecting telescope. The main mirror with a diameter of 605 cm has the shape of a paraboloid of revolution. The focal length of the mirror is 24 meters, the weight of the mirror without frame is 42 tons. The optical scheme of the BTA provides for operation in the main focus of the primary mirror and two Nesmith foci. In both cases, an aberration corrector can be applied.
The telescope is mounted on an alt-azimuth mount. The mass of the moving part of the telescope is about 650 tons. total weight telescope - about 850 tons.
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Chief Designer - Doctor of Technical Sciences Bagrat Konstantinovich Ioannisiani (LOMO). 
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The optical system of the telescope was manufactured at the Leningrad Optical-Mechanical Association. IN AND. Lenin (LOMO), Lytkarino Optical Glass Plant (LZOS), State Optical Institute. S. I. Vavilova (GOI).
For its manufacture, even separate workshops were built that had no analogues.
Do you know that?
- The blank for the mirror, cast in 1964, cooled down for more than two years.
- To process the workpiece, 12,000 carats of natural diamonds were used in the form of a powder; processing with a grinding machine manufactured at the Kolomna heavy machine tool plant was carried out for 1.5 years.
- The weight of the blank for the mirror was 42 tons.
- In total, the creation of a unique mirror lasted for 10 years.
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The main mirror of the telescope is subjected to temperature deformation, like all huge telescopes of this type. If the temperature of the mirror changes faster than 2° per day, the resolution of the telescope drops by a factor of one and a half. Therefore, special air conditioners are installed inside to maintain an optimal temperature regime. It is forbidden to open the dome of the telescope when the temperature difference between the outside and inside the tower is more than 10°, as such temperature changes can lead to the destruction of the mirror. 
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plumb line 
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Unfortunately, the North Caucasus is not the best place for such a megadevice. The fact is that in the mountains, open to all winds, there is a very high turbulence of the atmosphere, which significantly worsens visibility and does not allow using the full power of this telescope. 
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On May 11, 2007, the transportation of the first BTA primary mirror to the Lytkarinsky Optical Glass Plant (LZOS), which manufactured it, began for the purpose of deep modernization. The second primary mirror is now installed on the telescope. After processing in Lytkarino - removing 8 millimeters of glass from the surface and repolishing, the telescope should enter the top ten most accurate in the world. The upgrade was completed in November 2017. Installation and start of research are scheduled for 2018. 
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Hope you enjoyed the walk. Let's go to the exit. 
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Made with "
The first telescopes with a diameter of just over 20 mm and a modest magnification of less than 10x, which appeared at the beginning of the 17th century, made a real revolution in the knowledge of the cosmos around us. Today, astronomers are preparing to commission gigantic optical instruments thousands of times larger in diameter.
May 26, 2015 was a real holiday for astronomers around the world. On this day, Hawaii Governor David Egay authorized the start of the zero cycle of construction near the top of the extinct Mauna Kea volcano of a giant instrument complex, which in a few years will become one of the largest optical telescopes in the world.
The three largest telescopes of the first half of the 21st century will use different optical schemes. The TMT is built according to the Ritchey-Chrétien scheme with a concave primary mirror and a convex secondary one (both hyperbolic). The E-ELT has a concave primary mirror (elliptical) and a convex secondary mirror (hyperbolic). GMT uses Gregory's optical design with concave mirrors: primary (parabolic) and secondary (elliptical).
Giants in the arena
The new telescope is called the Thirty Meter Telescope (TMT) because its aperture (diameter) will be 30 m. If all goes according to plan, TMT will see the first light in 2022, and regular observations will begin another year later. The structure will be truly gigantic - 56 m high and 66 m wide. The main mirror will be composed of 492 hexagonal segments with a total area of 664 m². According to this indicator, TMT will surpass by 80% the Giant Magellan Telescope (GMT) with an aperture of 24.5 m, which in 2021 will come into operation at the Chilean Las Campanas Observatory, owned by the Carnegie Institution.
The 30-meter telescope TMT was built according to the Ritchey-Chrétien scheme, which is used in many currently operating large telescopes, including the currently largest Gran Telescopio Canarias with a main mirror with a diameter of 10.4 m. At the first stage, TMT will be equipped with three IR and optical spectrometers, and in the future it is planned to add several more scientific instruments to them.
However, the world champion TMT will not stay long. The opening of the European Extremely Large Telescope (E-ELT) with a record diameter of 39.3 m is scheduled for 2024, which will become the flagship instrument of the European Southern Observatory (ESO). Its construction has already begun at a three-kilometer altitude on Mount Cerro Armazones in Chile's Atacama Desert. The main mirror of this giant, composed of 798 segments, will collect light from an area of 978 m².
This magnificent triad will make up a group of next-generation optical supertelescopes that will have no competitors for a long time.
Anatomy of supertelescopes
The optical design of TMT goes back to a system that was proposed independently a hundred years ago by the American astronomer George Willis Ritchie and the Frenchman Henri Chrétien. It is based on a combination of a main concave mirror and a coaxial convex mirror of smaller diameter, both of which have the shape of a hyperboloid of revolution. Rays reflected from the secondary mirror are directed to the hole in the center of the main reflector and focused behind it. Using a second mirror in this position makes the telescope more compact and increases its focal length. This design has been implemented in many operating telescopes, in particular in the currently largest Gran Telescopio Canarias with a primary mirror 10.4 m in diameter, in the 10-meter twin telescopes of the Hawaiian Keck Observatory and in the four 8.2-meter telescopes of the Cerro Paranal Observatory, owned by ESO.
The optical system of E-ELT also contains a concave primary mirror and a convex secondary, but it has a number of unique features. It consists of five mirrors, and the main one is not a hyperboloid, as in TMT, but an ellipsoid.
GMT is designed completely differently. Its main mirror consists of seven identical monolithic mirrors with a diameter of 8.4 m (six make up a ring, the seventh is in the center). The secondary mirror is not a convex hyperboloid, as in the Ritchey-Chrétien scheme, but a concave ellipsoid located in front of the focus of the primary mirror. In the middle of the 17th century, such a configuration was proposed by the Scottish mathematician James Gregory, and was first implemented in practice by Robert Hooke in 1673. According to the Gregorian scheme, the Large Binocular Telescope (Large Binocular Telescope, LBT) was built at the International Observatory on Mount Graham in Arizona (both of its “eyes” are equipped with the same main mirrors as the GMT mirrors) and two identical Magellanic telescopes with an aperture of 6.5 m, which have been working at the Las Campanas Observatory since the early 2000s.
Strength is in the tools
Any telescope in itself is just a very large spotting scope. To turn it into an astronomical observatory, it must be equipped with highly sensitive spectrographs and video cameras.
TMT, which is designed for a service life of more than 50 years, will first of all be equipped with three measuring instruments mounted on a common platform - IRIS, IRMS and WFOS. IRIS (InfraRed Imaging Spectrometer) is a complex of video cameras very high definition, providing a view in the field of 34 x 34 arc seconds, and an infrared spectrometer. IRMS is a multi-slit infrared spectrometer, while WFOS is a wide-angle spectrometer that can simultaneously track up to 200 objects in an area of at least 25 square arc minutes. The design of the telescope includes a flat-rotating mirror that directs light to the devices you need at the moment, and it takes less than ten minutes to switch. In the future, the telescope will be equipped with four more spectrometers and a camera for observing exoplanets. According to current plans, one additional complex will be added every two and a half years. GMT and E-ELT will also have an extremely rich instrumentation.
Supergiant E-ELT will be the world's largest telescope with a 39.3 m primary mirror. It will be equipped with a state-of-the-art adaptive optics (AO) system with three deformable mirrors capable of eliminating distortions that occur at various heights and wavefront sensors for light analysis from three natural reference stars and four to six artificial ones (generated in the atmosphere using lasers). Thanks to this system, the resolution of the telescope in the near infrared zone in the optimal state of the atmosphere will reach six milliseconds of arc and will come close to the diffraction limit due to the wave nature of light.
European giant
The supertelescopes of the next decade will not come cheap. The exact amount is still unknown, but it is already clear that their total cost will exceed $ 3 billion. What will these gigantic tools give to the science of the Universe?
“The E-ELT will be used for astronomical observations on a wide range of scales, from the solar system to deep space. And on each scale scale, it is expected to provide exceptionally rich information, much of which other supertelescopes cannot give out,” he said. Popular mechanics» a member of the scientific team of the European giant Johan Liske, who is engaged in extragalactic astronomy and observational cosmology. - There are two reasons for this: firstly, E-ELT will be able to collect a lot of more light compared to its competitors, and secondly, its resolution will be much higher. Take, say, extrasolar planets. Their list is growing rapidly, by the end of the first half of this year it contained about 2000 titles. Now the main task is not to multiply the number of discovered exoplanets, but to collect specific data about their nature. This is exactly what E-ELT will do. In particular, its spectroscopic equipment will make it possible to study the atmospheres of stony Earth-like planets with a completeness and accuracy that is completely inaccessible to currently operating telescopes. This research program provides for the search for water vapor, oxygen and organic molecules, which may be the waste products of terrestrial organisms. There is no doubt that E-ELT will increase the number of contenders for the role of habitable exoplanets.”
The new telescope also promises other breakthroughs in astronomy, astrophysics and cosmology. As is known, there are considerable grounds for the assumption that the Universe has been expanding for several billion years with an acceleration due to dark energy. The magnitude of this acceleration can be determined from changes in the dynamics of the redshift of light from distant galaxies. According to current estimates, this shift corresponds to 10 cm/s per decade. This value is extremely small for measurements with current telescopes, but for the E-ELT such a task is quite capable. Its ultra-sensitive spectrographs will also provide more reliable data to answer the question of whether the fundamental physical constants are constant or whether they change over time.
E-ELT promises a genuine revolution in extragalactic astronomy, which deals with objects located outside Milky Way. Current telescopes make it possible to observe individual stars in nearby galaxies, but at long distances they fail. The European Super Telescope will provide an opportunity to see the brightest stars in galaxies millions and tens of millions of light years distant from the Sun. On the other hand, it will be able to receive light from the earliest galaxies, about which practically nothing is known yet. It will also be able to observe the stars near the supermassive black hole at the center of our Galaxy - not only to measure their speeds with an accuracy of 1 km / s, but also to discover now unknown stars in the immediate vicinity of the hole, where their orbital velocities approach 10% of the speed of light. . And this, as Johan Liske says, is far from a complete list of the unique capabilities of the telescope.
Magellan telescope
The giant Magellan telescope is being built by an international consortium that brings together more than a dozen different universities and research institutes in the United States, Australia and South Korea. Dennis Zaritsky, professor of astronomy at the University of Arizona and deputy director of the Stewart Observatory, explained to PM that Gregorian optics was chosen because it improves image quality over a wide field of view. This optical design is last years has proven itself well on several optical telescopes of the 6-8-meter range, and even earlier it was used on large radio telescopes.
Despite the fact that GMT is inferior to TMT and E-ELT in terms of diameter and, accordingly, the area of the light-collecting surface, it has many serious advantages. Its equipment will be able to simultaneously measure the spectra a large number objects, which is extremely important for survey observations. In addition, GMT optics provide very high contrast and the ability to reach far into the infrared. The diameter of its field of view, like that of TMT, will be 20 arc minutes.
According to Professor Zaritsky, GMT will take its rightful place in the triad of future supertelescopes. For example, with its help it will be possible to obtain information about dark matter, the main component of many galaxies. Its distribution in space can be judged by the motion of the stars. However, most of the galaxies where it dominates contain relatively few stars, and rather dim ones at that. GMT equipment will be able to track the movements of many more such stars than the instruments of any of the currently operating telescopes. Therefore, GMT will make it possible to more accurately map dark matter, and this, in turn, will make it possible to choose the most plausible model of its particles. Such a perspective acquires special value if one considers that, so far, dark matter has not been detected either by passive detection or obtained at an accelerator. Other research programs will also be carried out at GMT: the search for exoplanets, including terrestrial planets, the observation of the most ancient galaxies and the study of interstellar matter.
On earth and in heaven
In October 2018, the James Webb Telescope (JWST) is scheduled to be launched into space. It will work only in the orange and red zones of the visible spectrum, but it will be able to observe almost the entire mid-infrared range up to wavelengths of 28 microns (infrared rays with wavelengths over 20 microns are almost completely absorbed in the lower atmosphere by molecules carbon dioxide and water, so that ground-based telescopes do not notice them). Since it will be shielded from the thermal interference of the earth's atmosphere, its spectrometric instruments will be much more sensitive than ground-based spectrographs. However, the diameter of its main mirror is 6.5 m, and therefore, thanks to adaptive optics, the angular resolution of ground-based telescopes will be several times higher. So, according to Michael Bolte, observations at the JWST and ground-based supertelescopes will complement each other perfectly. As for the prospects for a 100-meter telescope, Professor Bolte is very cautious in his assessments: “In my opinion, in the next 20–25 years it will simply not be possible to create adaptive optics systems that can effectively work in tandem with a hundred-meter mirror. Perhaps this will happen somewhere in forty years, in the second half of the century.
Hawaiian project
"TMT is the only one of the three future supertelescopes to be located in the Northern Hemisphere," says Michael Bolte, a member of the board of directors of the Hawaiian project, professor of astronomy and astrophysics at the University of California at Santa Cruz. - However, it will be mounted not very far from the equator, at 19 degrees north latitude. Therefore, he, like other telescopes of the Mauna Kea observatory, will be able to survey the sky of both hemispheres, especially since this observatory is one of the best places on the planet in terms of observation conditions. In addition, TMT will work in conjunction with a group of nearby telescopes: the two 10-meter twins Keck I and Keck II (which can be considered the prototypes of TMT), as well as the 8-meter Subaru and Gemini-North. It is no coincidence that the Ritchey-Chrétien system is involved in the design of many large telescopes. It provides a good field of view and very effectively protects against both spherical and comatic aberration, which distorts images of objects that do not lie on the optical axis of the telescope. In addition, a truly magnificent adaptive optics is planned for TMT. It is clear that astronomers have good reason to expect that TMT observations will bring many remarkable discoveries.”
According to Professor Bolte, both TMT and other supertelescopes will contribute to the progress of astronomy and astrophysics, first of all, by once again pushing back the boundaries of the Universe known to science both in space and in time. Even 35–40 years ago, the observable space was mainly limited to objects no older than 6 billion years. It is now possible to reliably observe galaxies about 13 billion years old, whose light was emitted 700 million years after the Big Bang. There are candidates for galaxies with an age of 13.4 billion years, but this has not yet been confirmed. It can be expected that TMT instruments will be able to detect light sources only slightly younger (by 100 million years) than the Universe itself.
TMT will provide astronomy and many other opportunities. The results that will be obtained on it will make it possible to clarify the dynamics of the chemical evolution of the Universe, to better understand the processes of formation of stars and planets, to deepen knowledge about the structure of our Galaxy and its nearest neighbors and, in particular, about the galactic halo. But the main thing is that TMT, like GMT and E-ELT, is likely to allow researchers to answer questions of fundamental importance that cannot now not only be correctly formulated, but even imagined. This, according to Michael Bolte, is the main value of supertelescope projects.
The Large Azimuth Telescope (BTA) of the Special Astrophysical Observatory (SAO) of the Russian Academy of Sciences is again observing celestial objects. In 2018, the observatory replaced the main element of the telescope - a mirror with a diameter of 6 m, but it turned out to be unsuitable for full-fledged work. The mirror of 1979 was returned to the telescope.
Smaller is better
BTA, located in the village of Nizhny Arkhyz in the mountains of Karachay-Cherkessia, is one of the largest in the world. The telescope was launched in 1975.
In 1960–1970, two mirrors were made for the BTA at the Lytkarino Optical Glass Plant (LZOS) near Moscow. Glass blanks with a thickness of about 1 m and a weight of about 70 tons were first cooled for two years, and then they were polished with diamond powder for another seven years. The first mirror worked on the telescope for four years. In 1979, due to surface imperfections, it was replaced.
In the 1990s, scientists raised the issue of a new mirror replacement. By that time, it had already repeatedly undergone re-aluminization procedures: about once every five years, the reflective layer of aluminum was washed off the mirror with acids, and then a new coating was applied. Each such procedure worsened the surface of the mirror at the micro level. This affected the quality of observations.
In the early 2000s, the Russian Academy of Sciences came to grips with this issue. Two options were proposed: repolishing the first BTA mirror and a radical renovation of the telescope with the replacement of a 6-meter mirror with an 8-meter one.
In 2004, it was possible to buy in Germany a mirror blank of this size, made for the Very Large Telescope (VLT, Very Large Telescope) complex and not needed by it. An 8-meter mirror would provide a new level of vigilance and would return the Russian telescope to the top ten largest in the world.
However, this option also had disadvantages: high cost and high risks. Buying a blank would have cost €6-8 million, polishing would have cost about the same - it had to be done in Germany, because there is no equipment for mirrors of this diameter in Russia. It would be necessary to remake the upper part of the telescope structure and reconfigure all scientific equipment for the new luminosity.
“With the commissioning of an 8-meter mirror, only the dome of the telescope would have remained virtually untouched,” Dmitry Kudryavtsev, deputy director of the SAO, explained to Kommersant. “Now imagine all this in Russian realities with interruptions in funding for scientific projects. We could easily find ourselves in a situation where the telescope is literally taken to pieces, money does not come in, and we generally lose access to observations for an indefinite period.
It turned out as before
They didn’t even begin to calculate how much it would cost to redesign the telescope. “It was obvious that the Russian Academy of Sciences would not find such money,” Valery Vlasyuk, director of the SAO, told Kommersant. In 2004, the Academy decided to restore the first BTA mirror, which had been kept in a special container since 1979.
Photo: Kristina Kormilitsyna, Kommersant
The task was again entrusted to LZOS, which is now part of the Shvabe holding of the Rostec state corporation. To eliminate "congenital" defects from the surface of a mirror with an area of 28 sq. m, 8 mm of glass was cut, due to which its weight decreased by almost a ton. Polishing was planned to be carried out in three years, but due to interruptions in funding, it stretched for 10 years.
“The price increase is mainly explained by the financial crises that occurred between 2004 and 2018, and the subsequent inflation,” explains Vladimir Patrikeev, deputy head of the LZOS research and production complex. “For example, if in 2007 we brought a mirror from the Caucasus to the Moscow region for 3.5 million rubles, then in 2018 they were brought back already for 11 million rubles.
The restored mirror arrived in Nizhny Arkhyz in February 2018. about the transportation of a particularly fragile cargo weighing 42 tons, which took eight days.
Before being sent to the observatory, the restored mirror was certified for LZOS. However, after its installation in the standard frame of the BTA, significant deviations from the characteristics specified in the terms of reference were found.
Parabola started the process in a circle
“The quality of the mirror surface is evaluated by several parameters, the main of which are roughness and compliance with the parabolic shape,” says Mr. Kudryavtsev. “LZOS brilliantly coped with reducing the roughness of the mirror surface. If the second BTA mirror has 20 nanometers, then the restored one has only one nanometer. But there were problems with the shape of the mirror.
Based on the terms of reference, the standard deviation from the ideal paraboloid should have been no more than 95 nanometers. In reality, this parameter turned out to be at the level of 1 micron, which is ten times worse than the required value.
The problems with the restored mirror became clear almost immediately after its installation in the summer of 2018. Even then, it was decided to return the just replaced second mirror. But the observatory team was exhausted by the previous replacement, and besides, this multi-month procedure can only be carried out in the warm season.
BTA was put into operation with a low-quality mirror, if possible, the existing shortcomings were corrected with the help of mechanical systems. Due to the unstable and generally poor focusing on it, it was impossible to conduct photometric observations. Other scientific programs on the BTA were carried out, but with a loss of efficiency.
The return of the old mirror began on June 3, 2019. In September, test observations and the final adjustment of the telescope were carried out. Since October, BTA has returned to full-fledged work. 5 million rubles were spent on the operation.
“We are pleased with how the return of the old mirror went. It fits perfectly into the frame, the image quality is at the best level. For now, we will work like this, ”the director of the SAO RAS assured Kommersant.
Who is to blame and what to do
The joint commission of the SAO RAS, LZOS and NPO OPTIKA recognized the restored mirror as not meeting the terms of reference and in need of improvement. The formal reason is the lack of a stationary frame at the factory and computer modeling errors.
AT Soviet time the first mirror was polished in a real telescope frame, which was then transported from LZOS to the Caucasus and installed on the BTA. To polish the second mirror, a prototype frame was created at the factory - its simplified, cheap copy.
When in 2004 the Russian Academy of Sciences decided to restore the first mirror, the project involved the creation of a new frame imitation. The old one was scrapped in 2007.
And then there were problems with financing - there was no money to create a copy of the BTA frame. Then the experts decided that in the 21st century it is possible to polish a mirror not in a rigid frame, but with the help of computer simulation.
When performing control measurements, the mirror was supported by a steel tape. The resulting deformation of the glass was simulated, verified experimentally, and taken into account when adjusting the operation of the polishing machine. However, the inhomogeneity of the glass turned out to be much higher than the calculated one. In a regular frame, the restored mirror showed a deviation from the given shape by an order of magnitude worse than expected.
The commission recognized that the first mirror needed to be polished in imitation of the BTA frame. While it is stored in Nizhny Arkhyz. How much it will cost to repeat the process and whether it will be carried out again is still unknown. According to Vladimir Patrikeev, a representative of the plant, the decision to restore a copy of the frame at LZOS has not been made.
In the spent 250 million rubles. This included not only repolishing the mirror, says the director of the observatory, Valery Vlasyuk. The scope of work also included the transportation of the mirror for restoration and back to the BTA, the modernization of the polishing machine and the room temperature control system at LZOS, the repair of the BTA crane, which is used to rearrange the mirrors, the renovation of the technical premises of the telescope, and the creation of a mirror cooling system from scratch.
“All these improvements have remained with us and will reduce the cost of further work,” says Mr. Vlasyuk. “But so far the state has no money to continue work on the mirror. At the beginning of the 2000s, SAO RAS wrote letters to everyone strong of the world this, to all the oligarchs with a request to help update the BTA. And now we are also ready to ask the readers of Kommersant for help in order to still get a mirror with improved characteristics.
Julia Bychkova, Nizhny Arkhyz
