Telescopes, radio telescopes and gravitational wave detectors

Recently, astronomers have made remarkable achievements. First, they managed to take the world's first direct photograph of a black hole, which we write about elsewhere in this issue of MT. A little earlier, they first captured the exoplanet HR8799e (1) and its atmosphere. And all thanks to our cosmic senses.

As you know, there are many types of telescopes, differing mainly in what they shoot. telescopes optic they use visible light. roentgen detect objects in the wavelength range shorter than ultraviolet light. Telescopes in action in the infrared use wavelengths longer than visible light, and ultraviolet - shorter than visible light. Together they make up our cosmic species.

The rumor is called network of radio telescopes, of which the largest antennas have a diameter of up to half a kilometer. They work in the field. It is thanks to the global network of observatories of this type, called the name, that the now famous image of the massive black hole at the center of the galaxy Messier 87 was obtained.

And touch the name? Well, this feeling could be compared to the nascent gravitational wave astronomy. detectors such as LIGO finally, they feel the vibrations of space, which is associated with touch.

From the Canary Islands to South Africa

Although ten years have passed, the Gran Telescopio Canarias (GTC) in the Canary Islands still has the largest mirror of any telescope known to us.

The main mirror consists of 36 hexagonal segments. The observatory is also equipped with several supporting instruments such as the CanariCam, a camera capable of studying mid-range infrared light emitted by stars and planets. CanariCam also has the unique ability to display the direction of polarized light and block bright starlight, making exoplanets more visible.

We also often read in the media about discoveries made with a couple of telescopes. Kek I and II with mirrors of 10 m each, located at the WM Kecka observatory, near the summit of the Hawaiian volcano Mauna Kea. Telescopes connected together form Keck interferometer, being one of the largest in the world.

The University of California and the Lawrence Berkeley Laboratory began developing this equipment in 1977. American businessman and philanthropist Howard B. Keck donated $70 million needed for construction. Climbing Kek-1 began in 1985.

3. Size comparison of ground-based telescopes:

1. Very Large Telescope, 2. Extremely Large Telescope, 3. Keck Telescopes (Keck I and Keck II), 4. Thirty Meter Telescope, 5. Canary Large Telescope (Gran Telescopio Canarias), 6th Subaru Telescope, 7th South African big telescope. , 8th New Technology Telescope, 9th Giant Magellanic Telescope, 10th Large Large Synoptic Survey Telescope

The observatory's popularity grew and further donations were made that enabled the realization of the Keck 2. In 2004, the first adaptive optics laser system in a large telescope was used here, which creates an artificial star spot useful when looking at the sky as a guide. to correct atmospheric distortion.

One of the most famous optical telescopes South African Large Telescope (SALT), the largest ground-based optical instrument in the southern hemisphere, focused on spectroscopic research. Its primary mirror consists of 91 hexagonal mirrors.

Due to its location, SALT can take pictures that are not available to observatories in the northern hemisphere. The telescope is financed by a group of countries consisting of: Germany, Great Britain, New Zealand, India, South Africa, USA and ... Poland.

Another design, known not only in the astronomical community, Large twin-lens telescope (Large Binocular Telescope, LBT). Both mirrors of the telescope are monolithic, each with a diameter of 8,4 m. The total area of ​​mirrors is 111 m2. Thus, the capabilities of the LBT are comparable to a single-mirror telescope with a diameter of 11,8 m.

Subaru, a Japanese telescope operating in the visible light and infrared range, with the so-called active optics, has a monolithic mirror with a total diameter of 8,3 m (of which 8,2 m is used for observation), which was made by welding 55, mostly hexagonal, segments. It is equipped with 261 actuators to compensate for any distortion of the mirror. This instrument is located at the Hawaiian Mauna Kea Observatory.

Dry, transparent and no people

of course The above review is just an introduction to a journey to the capital of world astronomy, which is the Atacama Desert region in Chile. It was here that the largest and most powerful telescope complexes in the world were built. They are favored by natural conditions such as extremely dry air, clear skies and low population..

So there is, for example, the southern part Gemini Observatory, consisting of two 8,1-meter optical telescopes located in two different places on Earth. The twin telescopes are designed and operated by a consortium that includes the US, UK, Canada, Chile, Brazil, Argentina and Australia. One of the telescopes northern twin (Gemini North, also known as the Frederick C. Gillette Telescope) was built on Mauna Kea. Second - Southern semi-detached house (Gemini South) - erected at an altitude of 2500 m above sea level, on Mount Cerro Pajon in the Chilean Andes.

It is currently considered the largest optical astronomical observatory. Very Large Telescope (VLT, Very Large or Large, Telescope), owned by the European Southern Observatory (ESO). It is a set of four optical telescopes with adaptive and active optics, with a mirror diameter of 8,2 m each (2), which are complemented by four adjustable optical telescopes with a diameter of 1,8 m for interferometric studies.

Large telescopes are called Antu, Kuyen, Melipal and Yepun, which is associated with the mythology of the local Indians. In addition to them, the complex has a VISTA (Visible and Infrared Survey Telescope for Astronomy) telescope with a mirror diameter of 4,1 m and a VST (VLT Survey Telescope) with a mirror diameter of 2,6 m.

VLT is located in Paranal Observatory on the hill of Cerro Paranal (2635 m above sea level), in the Atacama Desert. The top of the hill is one of the driest places on Earth. The four main telescopes are housed in temperature-controlled buildings. This design minimizes the adverse effects that affect observing conditions, such as air turbulence in the telescope tube, which can occur due to temperature changes and wind. According to ESO, the VLT can "reconstruct images with angular resolution in the millisecond range, equivalent to seeing two car headlights on the Moon from Earth."

The largest telescopic mirrors operating on Earth

• Grand Canary Telescope (GTC): commissioning - 2002-2008 / diameter - 10,4 m / location - Roque de los Muchachos Observatory, Canary Islands, Spain

• Hobby'ego-Eberly'ego Telescope: 1996 / 10 m / McDonald Observatory, Texas, USA

• Kek I and II: 1993-1996 / 10 m / Mauna Kea Observatory, Hawaii, USA

• South African Large Telescope: 2005 / 9,2 m / South African Astronomical Observatory, Northern Cape, RPA

• Double Lens Large Telescope: 2004 / 8,4 m / Mount Graham International Observatory, Arizona, USA

• Subaru Telescope (JNLT): 1999 / 8,2 m / Mauna Kea Observatory, Hawaii, USA

• Antu, Kueyen, Melipal, Yepun (Very Large Telescope, VLT): 1998-2001 / 8,2 m / Paranal Observatory, Antofagasta Region, Chile

• Twins North and South: 1999-2001 / 8,1 m / Mauna Kea Observatory, Hawaii, USA and Cerro Pachon (CTIO), Coquimbo region, Chile

• Teleskop MMT (multi-mirror telescope): 2000 R. / 6,5 m / Whipple Observatory, Arizona, USA

• Magellan 1 and 2: 2000-2002 / 6,5 m / Las Campanas Observatory, Atacama Region, Chile

Future (slightly uncertain)

The classification of the largest ground-based telescopes may be completely revised in a few years. A XNUMX-meter building will be built on Mauna Kea Thirty meter telescope (TMT) with an estimated budget of $1,4 billion (4). Its planned aperture (the diameter of the hole through which light enters) is nine times larger than the surface of a Keck mirror, and it is expected to produce images with twelve times the resolution of those placed in orbit. Hubble Space Telescope.

4. Visualization of a thirty-meter telescope in Hawaii.

Chile is building a European Extremely large telescope (Extremely Large Telescope, ELT), with an aperture of 39 m (5). When operational, it will be the largest structure of its type operating in the visible light region in the world (6) and.

5. Visualization of the Extremely Large Telescope

Both TMT and ELT should be launched around 2024, although this is not at all necessary in the case of the former. The TMT project has been operating since the 90s. The first shovels were driven into the ground only in 2014, and soon the work was stopped due to protests by the natives of Hawaii against the installation of a telescope on their sacred mountain Mauna Kea. Litigation began. Last year, Hawaii's highest court ruled for a building permit, but can it continue?

6. Comparison of the size of the proposed ELT with the Etihad stadium in Manchester.

The third planned terrestrial giant is the Giant Magellanic Telescope at the Las Campanas Observatory in Chile. Its primary mirror will consist of seven segments each 8,4 m in diameter, giving a resolution equivalent to a single mirror 24,5 m in diameter (7).

7. Large Magellanic Telescope - visualization

A few years ago, GMT was expected to start operating in 2021. Today the date has been announced in three years. Astronomers say the telescope will be powerful enough to give us a direct view of the planets in other star systems, be able to detect light from the earliest moments of the universe, and possibly help answer the biggest questions in modern cosmology, including how galaxies form. dark matter and dark energy, as well as stars after the Big Bang.

Built in Chile. Large Synoptic Survey Telescope (LSST, Great Telescope for Synoptic Surveillance Observing) is based on the premise that large mirrors are not always the key to building the best telescope. It will have a mirror with an aperture of “only” 8,4 m in diameter (generally still quite large), but it compensates for it in range and speed. It's designed to scan the entire night sky rather than focusing on individual targets - using the largest digital camera on Earth to capture color time-lapse videos.

According to the LSST Corporation, which is building the telescope with the US Department of Energy and the National Science Foundation, "LSST will provide unprecedented three-dimensional maps of the distribution of masses in the universe" that could shed light on the mysterious dark energy that drives the accelerated expansion of space. It will also allow for a complete inventory of our own solar system, including potentially dangerous asteroids up to 100 m in size. The commissioning of the device is scheduled for 2022.

Ears are bigger than eyes

One of the world's most recognizable ground-based astronomical instruments has been operating since 1963 near Arecibo, Puerto Rico. It is a radio telescope with an antenna diameter of 305 m, which is much larger than the mirror of any existing or planned optical telescope of almost 40 m. aluminum panels.

The structure is used in radio astronomy, atmospheric and radar research by several institutions: Cornell University, SRI International, USRA, and the Metropolitan University of Puerto Rico in collaboration with the National Science Foundation. Access to the telescope is granted to scientific units based on applications reviewed by an independent commission. From 1963 to 2016, the radio telescope had the largest single dish in the world. Only in 2016 was a larger FAST radio telescope China.

The shape of the Arecibo dome is spherical (not parabolic like most radio telescopes). This is due to the way the radio telescope is pointed at the signal - the dish is stationary, but the receiver is moving. The receiver itself was placed on a 900-ton structure, suspended at a height of 150 m on eighteen cables, fixed on three reinforced concrete supports. The second and third bowls focus the reflected waves on the antenna. The mobility of the receiver makes it possible to direct the radio telescope to any point of the 40-degree cone around the zenith.

The Arecibo radio telescope has made many famous scientific discoveries possible. Thanks to him:

• On April 7, 1964, less than six months after commissioning, Mercury orbited the Sun not in 88, but in 59 days;
• in 1968, the discovery of periodic (33 ms) radio pulses from the Crab Nebula provided the first evidence for the existence of neutron stars;
• in 1974, Russell Alan Hulse and Joseph Hooton Taylor discovered the first binary system of pulsars and with its help tested the correctness of the theory of relativity - for which they later received the Nobel Prize in Physics;
• in 1990 Polish astronomer Aleksander Wolszan measured the oscillation periods of the pulsar PSR 1257+12, which allowed him to discover the first three extrasolar planets revolving around it;
• In January 2008, prebiotic particles of metamine and hydrogen cyanide were detected in the galaxy Arp 220 thanks to radio spectroscopy observations.

One of the largest ground-based astronomical instruments are radio antenna systems. Atacama Large Millimeter/Submillimeter Array (ALMA). They are located on the Chainantor plateau in the Chilean Andes, at an altitude of more than 5 meters. m above sea level. The observatory is located so high that astronomers working there have to use oxygen masks. It consists of 66 precision-made radio telescopes measuring 12 and 7 meters in diameter. ALMA is part of the Event Horizon team that recently “saw” a black hole.

ALMA operates in the range of 31,3-950 GHz. It has much higher sensitivity and resolution than existing submillimeter wavelength telescopes such as the James Clerk Maxwell Telescope or other radio telescope networks such as Submillimeter sensor (SMA) Oraz IRAM Plato de Boer.

Radiation of this wavelength often comes from the coldest and most distant objects in space, including from clouds of gas and dust in which new stars are born, and from distant galaxies at the edge of the observable universe. Space at these wavelengths has not yet been thoroughly explored, because valuable observations require instruments located in a place that guarantees not only good weather conditions for observations, but also very low humidity.

8. Visualization of an array of square kilometers in Western Australia.

A network of radio telescopes with a total area of ​​1 km has been planned for years² - Square kilometers array (SKA). It will be built in the southern hemisphere, in South Africa and Australia (8), where observations of the Milky Way are easiest and where electromagnetic interference is minimal. It is expected that there will be more than 100 thousand. low frequency antennas located in Australia and hundreds of antennas in South Africa. When this set is completed, SKA will be the king of radio telescopes, with a sensitivity 50 times greater than any radio telescope ever built. Such power could study the signals of the Universe 12 billion years ago! The complex will operate in the frequency range from 70 MHz to 10 GHz.

Anthony Schinkel, director of infrastructure consortium CSIRO SKA, the Australian research agency that manages the Australian side of the project, told the media.

-

The investment requires special infrastructure, including the location of 65 sq.m. fiber optic cables used to transmit data from antennas to SKA supercomputer devices.

It is expected to be operational by 2030. The observatory is being built by an international consortium, which includes Australia, Great Britain, Canada, China, India, Italy, New Zealand, Sweden and the Netherlands, as well as Botswana, Ghana, Kenya, Madagascar. , Mauritius, Mozambique, Namibia and Zambia.

Last year, in July, it was adopted by South Africa. MeerKAT radio telescopic network, an array of 64 antennas in the semi-arid Karoo region. Each antenna has a diameter of 13,5 m, and together they work as a single giant telescope, designed to collect radio signals from space. In the future, it will become part of the aforementioned intercontinental array of square kilometers. After the launch of MeerKAT, scientists connected a powerful MeerLITCH Optical Telescopefor simultaneous optical and radio study of space phenomena.

Paul Groot of Radboud University in the Netherlands told AFP.

The aforementioned giant radio telescope FAST (9), built by China in Guizhou Province, has a XNUMX-meter spherical telescope with a bowl diameter approximately equal to thirty football fields. Like the Arecibo radio telescope, it is equipped with a fixed main antenna and moving wave sensors above its dome, so that it can study objects that are not at the zenith - and can analyze objects farther from the zenith than the Arecibo instrument.

9. FAST radio telescope in China

FAST operates in the range of 0,7-3 GHz. The purpose of the radio telescope research is the accumulation of neutral hydrogen in the Milky Way and other galaxies, the detection of pulsars (both in our galaxy and beyond), the study of molecules in interstellar space, the search for variable stars and the search for extraterrestrial life (within the framework of SETI software). It is expected that FAST will be able to detect signal transmissions of alien civilizations at a distance of more than 1 meter. light years.

FAST is expected to be launched by the end of 2019. However, recently China approved a plan to build another, even larger radio telescope. It is scheduled to start operating in 2023.

The largest ground-based radio telescopes

• Spherical Telescope with XNUMXm Aperture (FAST): commissioning - 2019 (plan) / parabolic antenna diameter - 500 m / location - Pingtang, Guizhou Province, China

• Arecibo Observatory: 1963/305 m / Arecibo, Puerto Rico

• Radio telescope Zeleny Bank im. Robert S. Beard: 2002 / 100 years 110 m / Green Bank, West Virginia, USA

• Effelsberg radio telescope: 1971/100 m / Bad Münstereifel, Germany

• Lovella Radio Telescope: 1957/76 m / Jodrell Bank Observatory, Macclesfield in Cheshire, UK

Cosmic vision is weakening

We recently wrote about space telescopes in a separate report, on the occasion of the end of their activities. Kepler telescope. Since then, there have been several failures that make scientists, especially in the US, worry about their "eyes in space". Space telescopes, which began their era in 1990, are aging unless they are no longer out of service or broken. And he has neither the means nor much political will to replace them.

The direct space observatory program was established in the 70s and 80s and consisted of four large telescopic missions covering the entire spectrum of light in space.

Compton Gamma Observatory it was used to capture the most powerful explosions in the universe.

Spitzer Space Telescope has been used to search for infrared radiation from exoplanets and newborn stars.

Chandra X-ray Observatory can explore the depth of black holes and discovered evidence for the existence of dark matter and dark energy. The highlight of the show was, of course, visible and ultraviolet light. Hubble Space Telescope.

Comptona Telescope it stopped working in 2000 when a problem with its gyroscope, which allowed the telescope to rotate, grounded the device. Spitzer is slowly moving away from Earth and ends its mission when it loses contact with the command center the following year. This loss was expected, but the difficulties z Hubble and Chandra, which appeared at the turn of the year, were unexpected blows of fate.

Although Chandra returned to the network a few days after a failure in one of the gyroscopes forced the telescope into safe mode, Hubble's problems were also resolved, but a warning signal was lit by many scientists in the US. They felt that these devices did not last forever, and today there is nothing on the near horizon that could effectively replace the space astronomical infrastructure.

Flagship project of NASA's ongoing space observatory James Webb Space Telescope (JWST)but the commissioning of this 10 billionth unit is constantly delayed - due to design or investment errors. NASA recently announced that Webb will not launch until 2021 at the earliest.

Even if it finally succeeds, JWST only offers infrared observations. Prospects for research into other parts of the light spectrum are bleak at best. It is not known what will replace the Hubble telescope.

NASA also does not plan to have any major X-ray observatories ready to continue the Chandra mission. In a way, instead of Compton, a smaller one appeared Fermi Telescopehowever, it is now ten years old, meaning that it has exceeded its expected running time by as much as five years. Therefore, Hubble is expected to remain in orbit until at least 2027, and possibly even longer, until the JWST is finally in space.

Fortunately, other national space agencies are working on similar programs, but their implementation will also take some time. The European Space Agency is building X-ray Observatory ATHENAwhich will be launched in the 30s.

In 2016, China announced that it would build its own optical telescope with a field of view XNUMX times that of Hubble. However, it is not known when. However, in space, we already have a network of more modest "small and medium explorers" that cost much less than large projects. One of them was recently fired Transiting Exoplanet Exploration Satellite (TESS)aimed at finding unknown worlds.

What telescopes will be created and sent into space in the end, the so-called US will decide. NAS Decade ReviewA, scheduled for 2020. He will consider, in particular, the possibility of implementing the project Large Ultraviolet Optical Infrared Surveyor (LUVOIR), with a mirror diameter of 15 m. It is considered an improved version of the Hubble telescope. Like Hubble, this instrument will observe the universe in the ultraviolet, infrared and visible wavelengths.

Another project under consideration Habitable Exoplanet Observatory (HabEx). Its goal is to observe potentially habitable exoplanets around solar stars. HabEx will use a large stellar star (10) to block out starlight, allowing the telescope to study exoplanets in unprecedented detail.

10. Visualization of the work of the space coronograph (star shadow)

Potential successor to Chandra lynx, a proposed space telescope that will open up "invisible" space in the high-energy X-ray range. Finally, there is the design Origins Space Telescope is a far-infrared observatory that will penetrate dust clouds to get a vivid view of stars and exoplanets in star-forming regions.

They can be considered the next generation version. Herschel Space Observatory, a European mission that observed the universe in infrared for four years and was completed in 2013.

Improving Gravitational Wave Detectors

LIGO detectors (Laser Interferometer Gravitational-Wave Observatory) and Virgo detectors in April after a break resumed hunting for space-time ripples, that is, gravitational waves.

Our sense of cosmic touch is likely to feel the following vibrations again.

- said prof. Christopher Berry of Northwestern University USA.

So far, they have measured ten black hole collisions and one collision between two neutron stars — incredibly dense objects close in mass to the Sun, but no larger than a small city. However, right now, simply detecting gravitational waves is no longer the most interesting goal. Today, detectors serve essentially the same purpose as telescopes, but instead of light they measure gravity.

In February this year, American and British institutions announced that the LIGO gravitational wave detector will be greatly improved in the future.

The US National Science Foundation will contribute to the project Extended LIGO Plus (ALIGO+) $20,4 million, with UK Research adding another $13,7 million. Australia will also provide a financial contribution. The extension will apply to both locations where LIGO is located. As part of this, the device will be enriched, including a 300-meter long vacuum chamber that will allow you to manipulate the properties of the lasers used in the detector and reduce background noise.

LIGO consists of two L-shaped interferometers, one in Hanford, Washington and the other in Livingston, Louisiana. Both interferometers are 4 km long. LIGO operated from 2002-2010, then closed for expansion and launched again in 2015. Shortly thereafter, thanks to him, the famous discovery of gravitational waves was made. Since then, the observatory has undergone minor expansions that have increased its sensitivity by about 50%.

ALIGO+ will be a much more efficient tool than the setup used so far. It is assumed that thanks to improvements in detection technology, by 2022 the detector will register several gravitational events per day.

The expansion will increase not only the frequency, but also the quality of observations. Thanks to noise reduction, for example, scientists will be able to determine how black holes rotated before the merger. We are currently unable to make such observations. The vacuum chamber will reduce the pressure on the mirrors and reduce photon fluctuations. In addition, the mirrors will receive a new coating, which should reduce thermal noise by a factor of four. The first work carried out under ALIGO+ should start around 2023.

11. Comparison of mirror sizes for existing and planned telescopes.

It is also planned to build cosmic gravitational wave detector LISA Pathfinder. However, this is a more distant future - the earliest 30s.

***

The great discoveries that we are making with more and more powerful astronomical instruments encourage us to build new, more powerful and more sensitive observatories (11). If we can't fly to the far corners of space at the moment, then at least we're trying to look into them as closely as we can. We hope that our cosmic senses will tell us where to go once we have the technical capabilities for fast and deep space travel.