Hubble Orbital Telescope: a history of great discoveries. The most incredible facts about the Hubble telescope The creator of the modern telescope located on the ISS
To date, the development of optics and astronomy has led to a variety of telescope systems used. Types of telescopes are distinguished by purpose, by the optical design used and by the mount design.
By purpose, telescopes are divided into visual and photographic; the latter are divided into infrared, visible, ultraviolet and x-ray telescopes. There are also solar telescopes and out-of-eclipse coronagraphs - instruments that allow you to image the solar corona. According to the optical design used, all types of telescopes can be divided into lens (refractors), mirror (reflectors) and mirror-lens (catadioptrics). The telescope mount can be fixed (with external redirection of light), azimuthal (with vertical and horizontal rotation) and equatorial (with rotation relative to the celestial sphere). In addition to optical telescopes, radio and neutrino telescopes are also possible, but you cannot look into either one, and all information is obtained by electronic processing of signals from various sensors.
Stellar telescopes for professional astronomy have currently reached an aperture of 8 - 11 m. In terms of their design, these are reflectors for shooting at direct focus, due to small fields, not equipped with any intermediate optics. Their goal is the highest resolution at the highest possible aperture ratio, which leads to the need to adjust the shape of the main mirror to atmospheric fluctuations.
This, as it is called, adaptive optics, first appeared in the 1980s in relation to combat laser systems designed to destroy satellites, its civilian use began in the VLT telescopes of the European Southern Observatory, installed in Chile. The mirrors of all five telescopes in this group, having an aperture of 8.3 meters, can quickly be deformed by a small amount using a system of hydraulic jacks located on their rear side. The magnitude of the deformations is calculated by a computer in real time based on the distortions of the test image of the “artificial star” created in the upper layers of the atmosphere by an infrared laser installed on the telescope.
A little to the side of the test image, the same mirror creates a working one, used for research tasks.
The two Keck telescopes installed at the Hawaiian Observatory in the USA and having an aperture of over 11 m use a similar principle for compensating for atmospheric distortions, but instead of a solid mirror, the image on the photodetector is created by a whole system of dozens of segments, each of which is rotated by its own jack. These instruments have already surpassed the Hubble Orbital Telescope in resolution, but there are European and American projects of telescopes with segmented mirrors with an aperture of 30 - 60 meters.
However, if in general an aperture of 20 meters is still unattainable for an optical telescope, then for some particular tasks it can be tens or hundreds of meters. We are talking about bringing images from two different telescopes aimed at the same area of the sky into one point. This principle, called the Coudé focus in astronomy, is used in problems of stellar interferometry, which makes it possible to reconstruct images of individual stars and accurately measure the diameter of their disks, which is unattainable by any other means. However, neither simple photography, nor even more so visual observation using such a scheme will yield anything - computer processing of a series of images is necessary. An example of a working stellar interferometer is the Australian system with a distance of 188 meters between telescopes.
For wide-field observations and targeted searches for new objects, such as novae, asteroids and trans-Neptunian objects, types of telescopes of predominantly catadioptric design - Schmidt, Hamilton or Maksutov - are used. The speed of exposure, data transfer and computer processing also plays an important role in organizing such searches. An amateur armed with a digital SLR camera with a 200 - 300 mm telephoto lens also has a certain chance of success. Moreover, by focal length, and not by aperture - professionals will never be able to observe everywhere at the same time, and a flaring nova is often visible through ordinary binoculars.
Refractors in professional stellar astronomy now remain only in the form of the mentioned telephoto lenses and finders of larger instruments. The huge achromats of the past, both visually and photographically, are completely covered by more than modest reflectors and catadioptrics. Apochromats are mainly used to search for space debris and near-Earth objects in the range of the smallest apertures - here they turn out to be advantageous.
Solar telescopes, as their name suggests, are designed to observe a single object in space. Observations, for obvious reasons, are carried out during the day and have their own specifics. First of all, it is necessary to reduce the brightness of the image created by the solar telescope by several hundred thousand times. This problem is solved by installing aperture solar filters.
In addition, all the optics of reflective solar telescopes are uncoated, which, however, only reduces the brightness by tens of times. The other part is achieved by using ultra-low aperture, stretching the final image into a circle with a diameter of up to a meter or more with a moderate aperture of the telescope itself. The latter, however, should not be too small and provide a resolution sufficient to distinguish objects on the surface of the Sun separated by an interval of no more than several hundred kilometers.
The combination of these largely contradictory requirements leads to the fact that the solar telescope is often made stationary, for which a special tower is built. In this case, the rays of the daylight are directed into the tower using a coelostat - a special system of two flat mirrors larger than the telescope aperture in size.
The specific nature of observations from Earth means that we cannot observe the far side of the Sun until it turns towards us in about 29 days. This drawback is completely eliminated in the SOHO space system, in which three solar telescopes are placed on stations placed in a heliocentric orbit and placed at the vertices of a moving equilateral triangle.
“Relatives” of solar telescopes are out-of-eclipse coronagraphs – devices of even more narrow specialization. Neither sunspots nor granules can be seen in them, but the dim glow of the corona is cut off simultaneously from both atmospheric illumination and the powerful glow of the disk itself.
The coronagraph was invented by the French optician Lyot in 1862, but they really became interested in it during the Second World War, when magnetic storms were predicted by the shape of the solar corona. The implementation of the largely forgotten idea became secret until the early 50s. With the invention of narrow-band filters tuned to the absorption lines of the hydrogen and calcium spectra, the coronagraph became publicly available and could be sold to anyone.
Ultraviolet telescopes are similar in design to conventional reflectors. The Earth's atmosphere transmits near-field ultraviolet radiation with a wavelength of up to 350 nm, so ground-based ultraviolet telescopes are placed in high mountain areas. The objects of their research can be both individual stars and galaxies, which are recorded by emissions of ultraviolet radiation during processes occurring in their cores. Due to their shorter wavelength, the optics of ultraviolet telescopes must be performed with greater precision than those of visible telescopes.
The limiting element in terms of light transmission is the refractive parts, which in the case of small lenses are made of fused quartz. In this case, residual chromatism is allowed. The creation of wide-field ultraviolet telescopes represents a serious technological problem, since conventional Schmidt and Ritchie-Chrétien cameras use corrective lenses, which are difficult to make from quartz. One of the solutions is the so-called. Schmidt mirror camera, in which the correction element is made in the form of an inclined mirror with a profile close to flat. Such a system is sometimes installed on satellites, but is very sensitive to misalignment.
Infrared telescopes provide a unique opportunity to observe stars through dust clouds, which weaken their apparent brightness in the visible range by several hundred magnitudes. This is due to the fact that the radiation heats the dust particles and is re-emitted by it in the infrared range. In particular, this observation method made it possible to construct a closed orbit of a star closely orbiting the center of our Galaxy, which provided reliable evidence that the central object is a black hole.
In addition to stars, the objects of observation in such telescopes can be the planets of the solar system and their satellites, which makes it possible to clarify the structure of their surface by the nature of its thermal radiation. The greater penetrating power allows the use of infrared telescopes to search for trans-Neptunian objects and near-Earth asteroids.
Due to the nature of thermal radiation, an infrared telescope must always be kept very cool. A cryostat, a device that maintains a telescope at a constant negative temperature, was previously made on the basis of “dry ice” - solid carbon dioxide, then liquid nitrogen began to be used and, currently, liquid helium. An infrared matrix is a very expensive device, the cost of which reaches millions of dollars. The optics of infrared telescopes are predominantly specular; due to the longer wavelength of thermal radiation than visible radiation, the optics can be performed with a lesser degree of accuracy. The largest ground-based infrared telescope is installed at the European Southern Observatory in Chile and has an aluminum mirror with adaptive optics with a total aperture of 12 m.
In most cases, X-ray telescopes are launched into space, since the earth's atmosphere greatly attenuates X-rays. Another specificity of the received radiation is the virtual absence of its refraction by most transparent materials and reflection by metals only at a very acute angle. This forces the use of focusing high-energy X-ray quanta either using off-axis parabolic mirrors with a special coating, or using the principle of a coding aperture.
In the first case, the mirror is placed almost tangentially to the incident wavefront and in most cases is coated with gold or iridium. Sometimes a dielectric coating can be used, up to several hundred layers. When using a coding aperture, the image on the photodetector is created by passing the radiation under study through a matrix formed by transparent and opaque cells placed in a certain sequence. The resulting image is reconstructed by the on-board computer of the spacecraft.
Thus, the types of telescopes of modern astronomy represent powerful means of observation, which in recent years have led to truly revolutionary discoveries.
2.Astronomical observatory
Astronomical observatory- an institution designed to conduct systematic observations of celestial bodies; It is usually built on a high area, from which a wide horizon would open in all directions. Each observatory is equipped with telescopes, both optical and operating in other areas of the spectrum (Radio Astronomy).
Space observatories play a major role in the development of astronomy. The greatest scientific achievements of recent decades rely on knowledge gained from spacecraft.
A large amount of information about celestial bodies does not reach the earth because... it is hampered by the atmosphere we breathe. Most of the infrared and ultraviolet range, as well as X-rays and gamma rays of cosmic origin, are inaccessible for observation from the surface of our planet. To study space in these ranges, it is necessary to move the telescope beyond the atmosphere. Research results obtained using space observatories revolutionized man's understanding of the universe.
The first space observatories did not exist in orbit for long, but advances in technology made it possible to create new instruments for exploring the universe. Modern space telescope- a unique complex that has been developed and operated jointly by scientists from many countries for several decades. Observations obtained using many space telescopes are available for free use by scientists and astronomy enthusiasts from all over the world.
Infrared telescopes
Designed for space observations in the infrared range of the spectrum. The disadvantage of these observatories is their heavy weight. In addition to the telescope, a cooler has to be placed into orbit, which should protect the telescope’s IR receiver from background radiation - infrared quanta emitted by the telescope itself. This has resulted in very few infrared telescopes operating in orbit throughout the history of spaceflight.
Hubble Space Telescope
Image by ESO
On April 24, 1990, with the help of the American shuttle Discovery STS-31, the largest near-Earth observatory, the Hubble Space Telescope, weighing more than 12 tons, was launched into orbit. This telescope is the result of a joint project between NASA and the European Space Agency. The Hubble Space Telescope is designed to last for a long time. The data obtained with its help are available on the telescope website for free use by astronomers around the world.
Ultraviolet telescopes
The ozone layer surrounding our atmosphere almost completely absorbs ultraviolet radiation from the Sun and stars, so UV quanta can only be detected outside of it. Astronomers' interest in UV radiation is due to the fact that the most common molecule in the Universe, the hydrogen molecule, emits in this spectral range. The first ultraviolet reflecting telescope with a mirror diameter of 80 cm was launched into orbit in August 1972 on the joint American-European Copernicus satellite.
X-ray telescopes
X-rays bring us information from space about powerful processes associated with the birth of stars. The high energy of X-ray and gamma rays allows them to be recorded one at a time, with an accurate indication of the registration time. Due to the fact that X-ray detectors are relatively easy to manufacture and light in weight, X-ray telescopes have been installed on many orbital stations and even interplanetary spacecraft. In total, more than a hundred such instruments have been in space.
Gamma-ray telescopes
Gamma radiation is similar in nature to x-ray radiation. To record gamma rays, methods similar to those used for X-ray studies are used. Therefore, space telescopes often examine both X-rays and gamma rays simultaneously. Gamma radiation received by these telescopes brings us information about the processes occurring inside atomic nuclei, as well as about the transformations of elementary particles in space.
Electromagnetic spectrum studied in astrophysics
| Wavelengths | Spectrum area | Passing through the earth's atmosphere | Radiation receivers | Research methods |
| <=0,01 нм | Gamma radiation | Strong absorption |
||
| 0.01-10 nm | X-ray radiation | Strong absorption O, N2, O2, O3 and other air molecules |
Photon counters, ionization chambers, photoemulsions, phosphors | Mainly extra-atmospheric (space rockets, artificial satellites) |
| 10-310 nm | Far ultraviolet | Strong absorption O, N2, O2, O3 and other air molecules |
Extra-atmospheric | |
| 310-390 nm | Near ultraviolet | Weak absorption | Photomultipliers, photoemulsions | From the surface of the Earth |
| 390-760 nm | Visible radiation | Weak absorption | Eye, photoemulsions, photocathodes, semiconductor devices | From the surface of the Earth |
| 0.76-15 microns | Infrared radiation | Frequent absorption bands of H2O, CO2, etc. | Partially from the surface of the Earth | |
| 15 µm - 1 mm | Infrared radiation | Strong molecular absorption | Bolometers, thermocouples, photoresistors, special photocathodes and photoemulsions | From balloons |
| > 1 mm | Radio waves | Radiation with wavelengths of about 1 mm, 4.5 mm, 8 mm and from 1 cm to 20 m is transmitted | Radio telescopes | From the surface of the Earth |
Space observatories
| Agency, country | Observatory name | Spectrum area | Launch year |
| CNES & ESA, France, European Union | COROT | Visible radiation | 2006 |
| CSA, Canada | MOST | Visible radiation | 2003 |
| ESA & NASA, European Union, USA | Herschel Space Observatory | Infrared | 2009 |
| ESA, European Union | Darwin Mission | Infrared | 2015 |
| ESA, European Union | Gaia mission | Visible radiation | 2011 |
| ESA, European Union | International Gamma Ray Astrophysics Laboratory (INTEGRAL) |
Gamma radiation, X-ray | 2002 |
| ESA, European Union | Planck satellite | Microwave | 2009 |
| ESA, European Union | XMM-Newton | X-ray | 1999 |
| IKI & NASA, Russia, USA | Spectrum-X-Gamma | X-ray | 2010 |
| IKI, Russia | RadioAstron | Radio | 2008 |
| INTA, Spain | Low Energy Gamma Ray Imager (LEGRI) | Gamma radiation | 1997 |
| ISA, INFN, RSA, DLR & SNSB | Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) |
Particle detection | 2006 |
| ISA, Israel | AGILE | X-ray | 2007 |
| ISA, Israel | Astrorivelatore Gamma ad Immagini LEggero (AGILE) |
Gamma radiation | 2007 |
| ISA, Israel | Tel Aviv University Ultraviolet Explorer (TAUVEX) |
Ultraviolet | 2009 |
| ISRO, India | Astrosat | X-ray, Ultraviolet, Visible radiation | 2009 |
| JAXA & NASA, Japan, USA | Suzaku (ASTRO-E2) | X-ray | 2005 |
| KARI, Korea | Korea Advanced Institute of Science and Technology Satellite 4 (Kaistsat 4) |
Ultraviolet | 2003 |
| NASA & DOE, USA | Dark Energy Space Telescope | Visible radiation | |
| NASA, USA | Astromag Free-Flyer | Elementary particles | 2005 |
| NASA, USA | Chandra X-ray Observatory | X-ray | 1999 |
| NASA, USA | Constellation-X Observatory | X-ray | |
| NASA, USA | Cosmic Hot Interstellar Spectrometer (CHIPS) |
Ultraviolet | 2003 |
| NASA, USA | Dark Universe Observatory | X-ray | |
| NASA, USA | Fermi Gamma-ray Space Telescope | Gamma radiation | 2008 |
| NASA, USA | Galaxy Evolution Explorer (GALEX) | Ultraviolet | 2003 |
| NASA, USA | High Energy Transient Explorer 2 (HETE 2) |
Gamma radiation, X-ray | 2000 |
| NASA, USA | Hubble Space Telescope | Ultraviolet, Visible radiation | 1990 |
| NASA, USA | James Webb Space Telescope | Infrared | 2013 |
| NASA, USA | Kepler Mission | Visible radiation | 2009 |
| NASA, USA | Laser Interferometer Space Antenna (LISA) |
Gravitational | 2018 |
| NASA, USA | Nuclear Spectroscopic Telescope Array (NuSTAR) |
X-ray | 2010 |
| NASA, USA | Rossi X-ray Timing Explorer | X-ray | 1995 |
| NASA, USA | SIM Lite Astrometric Observatory | Visible radiation | 2015 |
| NASA, USA | Spitzer Space Telescope | Infrared | 2003 |
| NASA, USA | Submillimeter Wave Astronomy Satellite (SWAS) |
Infrared | 1998 |
| NASA, USA | Swift Gamma Ray Burst Explorer | Gamma radiation, X-ray, Ultraviolet, Visible radiation |
2004 |
| NASA, USA | Terrestrial Planet Finder | Visible radiation, Infrared | |
| NASA, USA | Wide-field Infrared Explorer (WIRE) |
Infrared | 1999 |
| NASA, USA | Wide-field Infrared Survey Explorer (WISE) |
Infrared | 2009 |
| NASA, USA | WMAP | Microwave | 2001 |
Optical telescopic systems are used in astronomy (for observing celestial bodies), in optics for various auxiliary purposes: for example, to change the divergence of laser radiation. The telescope can also be used as a telescope to solve problems of observing distant objects. The very first drawings of a simple lens telescope were discovered in the notes of Leonardo Da Vinci. Built a telescope in Lipperhey. Also, the creation of the telescope is attributed to his contemporary Zachary Jansen.
Story
The year of invention of the telescope, or rather the telescope, is considered to be 1607, when the Dutch spectacle maker John Lippershey demonstrated his invention in The Hague. However, he was refused a patent due to the fact that other masters, such as Zachary Jansen from Middelburg and Jacob Metius from Alkmaar, already possessed copies of telescopes, and the latter, soon after Lippershey, submitted a request to the States General (Dutch parliament) for patent Later research showed that telescopes were probably known earlier, as early as 1605. In his Supplements to Vitellius, published in 1604, Kepler examined the path of rays in an optical system consisting of a biconvex and a biconcave lens. The very first drawings of the simplest lens telescope (both single-lens and double-lens) were discovered in the notes of Leonardo da Vinci, dating back to 1509. His note has been preserved: “Make glass to look at the full moon” (“Atlantic Codex”).
The first person to point a telescope into the sky, turning it into a telescope, and obtain new scientific data, was Galileo Galilei. In 1609, he created his first telescope with three times magnification. In the same year, he built a telescope with eightfold magnification, about half a meter long. Later, he created a telescope that gave a 32-fold magnification: the length of the telescope was about a meter, and the diameter of the lens was 4.5 cm. It was a very imperfect instrument, which had all possible aberrations. Nevertheless, with its help, Galileo made a number of discoveries.
The name "telescope" was proposed in 1611 by the Greek mathematician Ioannis Demisiani (Giovanni Demisiani) for one of Galileo's instruments shown at a country symposium of the Accademia dei Lincei. Galileo himself used the term Lat. for his telescopes. perspicillum.
"Telescope of Galileo", Museum Galileo (Florence)
The 20th century also saw the development of telescopes that operated in a wide range of wavelengths from radio to gamma rays. The first purpose-built radio telescope went into operation in 1937. Since then, a huge variety of sophisticated astronomical instruments have been developed.
Optical telescopes
The telescope is a tube (solid, frame) mounted on a mount, equipped with axes for pointing at and tracking the object of observation. A visual telescope has a lens and an eyepiece. The rear focal plane of the lens is aligned with the front focal plane of the eyepiece. Instead of an eyepiece, photographic film or a matrix radiation receiver can be placed in the focal plane of the lens. In this case, the telescope lens, from the point of view of optics, is a photographic lens, and the telescope itself turns into an astrograph. The telescope is focused using a focuser (focusing device).
According to their optical design, most telescopes are divided into:
- Lens ( refractors or dioptric) - a lens or lens system is used as a lens.
- Mirror ( reflectors or cataptric) - a concave mirror is used as a lens.
- Mirror-lens telescopes (catadioptric) - a spherical primary mirror is usually used as a lens, and lenses are used to compensate for its aberrations.
This can be a single lens (Helmut system), a lens system (Volosov-Galpern-Pechatnikova, Baker-Nana), Maksutov’s achromatic meniscus (systems of the same name), or a planoid aspheric plate (Schmidt, Wright systems). Sometimes the primary mirror is shaped like an ellipsoid (some meniscus telescopes), an oblate spheroid (Wright camera), or simply a slightly shaped irregular surface. This eliminates residual aberrations of the system.
In addition, to observe the Sun, professional astronomers use special solar telescopes, which differ in design from traditional stellar telescopes.
Radio telescopes
Very Large Array radio telescopes in New Mexico, USA
Radio telescopes are used to study space objects in the radio range. The main elements of radio telescopes are a receiving antenna and a radiometer - a sensitive radio receiver, frequency tunable, and receiving equipment. Since the radio range is much wider than the optical range, various designs of radio telescopes are used to record radio emission, depending on the range. In the long-wave region (meter range; tens and hundreds of megahertz), telescopes are used that are composed of a large number (tens, hundreds or even thousands) of elementary receivers, usually dipoles. For shorter waves (decimeter and centimeter range; tens of gigahertz), semi- or fully rotating parabolic antennas are used. In addition, to increase the resolution of telescopes, they are combined into interferometers. When several single telescopes located in different parts of the globe are combined into a single network, they talk about very long baseline radio interferometry (VLBI). An example of such a network is the American VLBA (Very Long Baseline Array) system. From 1997 to 2003, the Japanese orbital radio telescope HALCA operated. Highly Advanced Laboratory for Communications and Astronomy), included in the VLBA network of telescopes, which significantly improved the resolution of the entire network. The Russian orbital radio telescope Radioastron is also planned to be used as one of the elements of the giant interferometer.
Space telescopes
The earth's atmosphere transmits radiation well in the optical (0.3-0.6 microns), near infrared (0.6-2 microns) and radio (1 mm - 30 ) ranges. However, as the wavelength decreases, the transparency of the atmosphere greatly decreases, as a result of which observations in the ultraviolet, X-ray and gamma ranges become possible only from space. An exception is the registration of ultra-high-energy gamma radiation, for which methods of cosmic ray astrophysics are suitable: high-energy gamma photons in the atmosphere generate secondary electrons, which are recorded by ground-based installations using Cherenkov glow. An example of such a system is the CACTUS telescope.
In the infrared range there is also strong absorption in the atmosphere, however, in the region of 2-8 microns there are a number of transparency windows (as in the millimeter range) in which observations can be made. In addition, since most of the absorption lines in the infrared range belong to water molecules, infrared observations can be made in dry regions of the Earth (of course, at those wavelengths where windows of transparency form due to the absence of water). An example of such a telescope placement is the South Pole Telescope. South Pole Telescope), installed at the geographic south pole, operating in the submillimeter range.
In the optical range, the atmosphere is transparent, however, due to Rayleigh scattering, it transmits light of different frequencies differently, which leads to a distortion of the spectrum of luminaries (the spectrum shifts towards red). In addition, the atmosphere is always heterogeneous; currents (winds) constantly exist in it, which leads to image distortion. Therefore, the resolution of Earth-based telescopes is limited to approximately 1 arcsecond, regardless of the telescope aperture. This problem can be partially solved by using adaptive optics, which can greatly reduce the influence of the atmosphere on image quality, and by raising the telescope to a higher altitude, where the atmosphere is thinner - in the mountains, or in the air on airplanes or stratospheric balloons. But the greatest results are achieved when telescopes are taken into space. Outside the atmosphere, distortion is completely absent, so the maximum theoretical resolution of the telescope is determined only by the diffraction limit: φ=λ/D (angular resolution in radians is equal to the ratio of the wavelength to the aperture diameter). For example, the theoretical resolution of a space telescope with a mirror with a diameter of 2.4 meters (like a telescope
Space telescopes are typically telescopes that operate outside the Earth's atmosphere and thus do not bother to peer through that atmosphere. The most famous space telescope today is the Hubble Space Telescope, which has discovered hundreds of exoplanets, revealed many spectacular galaxies, cosmic events, and expanded the horizons of our view into space. Hubble will be replaced by the James Webb Space Telescope, which will be launched into space in 2018 and whose mirror will be almost three times the diameter of Hubble's mirror. After James Webb, scientists plan to send the High-Definition Space Telescope (HDST) into space, but this is only in the plans for now. Be that as it may, space telescopes have and will continue to account for the majority of our discoveries in deep space.
We imagine space as a dark, cold and quiet place where there is nothing but the endless Universe around. However, one can argue about the silence of outer space. Thousands of different radio signals travel throughout the Universe. They are emitted by various space objects and most of these signals are nothing more than noise and interference. But among them there are also those that cannot be classified as interference. And recently it registered a huge Chinese radio telescope.
Space telescopes
Observing planets, stars, nebulae, and galaxies directly from space - astronomers have dreamed of such an opportunity a long time ago. The fact is that the Earth’s atmosphere, which protects humanity from many cosmic troubles, at the same time prevents observations of distant celestial objects. Cloud cover and instability of the atmosphere itself distort the resulting images, and even make astronomical observations impossible. Therefore, as soon as specialized satellites began to be sent into orbit, astronomers began to insist on launching astronomical instruments into space.
Hubble's firstborn. A decisive breakthrough in this direction occurred in April 1990, when one of the shuttles launched the Hubble telescope weighing 11 tons into space. A unique instrument with a length of 13.1 m and a main mirror diameter of 2.4 m, which cost US taxpayers 1 .2 billion dollars, was named after the famous American astronomer Edwin Hubble, who was the first to notice that galaxies scatter from a certain center in all directions.
The Hubble Space Telescope and its photograph of the pillars of creation - the birth of new stars in the Eagle Nebula
Hubble got off to a rocky start. Two months after it was launched into orbit at an altitude of 613 km, it became obvious that the main mirror was defective. Its curvature at the edges differed from the calculated one by several microns - a fiftieth of the thickness of a human hair. However, even this small amount was enough for Hubble to be nearsighted, and the image it received was blurry.
At first, they tried to correct the image defects on Earth using computer correction programs, but this helped little. Then it was decided to carry out a unique operation to correct “myopia” right in space, by prescribing special “glasses” to Hubble - a corrective optical system.
And so, in the early morning of December 2, 1993, seven astronauts set off on the shuttle Endeavor to carry out a unique operation. They returned to Earth after 11 days, having accomplished the seemingly impossible during five spacewalks - the telescope “received the light.” This became obvious after receiving the next batch of photographs from him. Their quality has increased significantly.
Over the years of its flight, the space observatory has made several tens of thousands of revolutions around the Earth, “winding up” billions of kilometers.
The Hubble telescope has already made it possible to observe more than 10 thousand celestial objects. Two and a half trillion bytes of information collected by the telescope are stored on 375 optical disks. And it still continues to accumulate. The telescope made it possible to discover the existence of black holes in space, revealed the presence of an atmosphere on Jupiter’s satellite Europa, discovered new satellites of Saturn, and allowed us to look into the most remote corners of space...
During the second "inspection" in February 1997, the telescope's high-resolution spectrograph, faint object spectrograph, star pointing device, tape recorder, and solar panel electronics were replaced.
According to the plan, Hubble was supposed to “retire” in 2005. However, it still works properly to this day. Nevertheless, he is already preparing for an honorable resignation. The veteran will be replaced by a new unique space telescope in 2015, named after James Webb, one of the directors of NASA. It was under him that astronauts first landed on the moon.
What does the coming day have in store for us? Since the new telescope will have a composite mirror with a diameter of 6.6 m and a total area of 25 square meters. m, it is believed that Webb will be 6 times more powerful than its predecessor. Astronomers will be able to observe objects that glow 10 billion times fainter than the faintest stars visible to the naked eye. They will be able to see the stars and galaxies that witnessed the infancy of the Universe, and also determine the chemical composition of the atmospheres of planets orbiting distant stars.
More than 2,000 specialists from 14 countries are taking part in the creation of the new orbital infrared observatory. Work on the project began back in 1989, when NASA proposed the Next Generation Space Telescope project to the world scientific community. The diameter of the main mirror was planned to be no less than 8 m, but in 2001 ambitions had to be tempered and stopped at 6.6 m - a large mirror does not fit into the Ariane 5 rocket, and the shuttles, as we know, have already stopped flying.
"James Webb" will fly into space under the cover of a "star umbrella". Its shield in the shape of a giant flower will protect the telescope from stellar radiation that makes it difficult to see distant galaxies. Huge umbrella with an area of 150 sq. m will consist of five layers of polyamide film, each of which is no thicker than a human hair. For six years, this film was tested for strength, checking whether it could withstand bombardment by micrometeorites. The three inner layers will be covered with an ultra-thin layer of aluminum, and the outer two will be treated with silicon alloy. The sunscreen will function like a mirror, reflecting radiation from the Sun and other luminaries back into space.
As you know, it is so cold in space that in six months the telescope will cool to a temperature below –225 °C. But it is also too high for MIRI, a device for observations in the mid-infrared range (Mid-Infrared Instrument), consisting of a camera, coronagraph and spectrometer. MIRI will have to be further cooled using helium-based refrigeration equipment to a temperature of -266 °C - just 7 °C above absolute zero.
In addition, astronomers tried to find a point in space where the telescope could remain for years, turning its “back” simultaneously to the Earth, the Moon and the Sun, shielding itself from their radiation with a screen. In a year, which will take one revolution around the Sun, the telescope will be able to survey the entire celestial space.
The disadvantage of this Lagrange libration point L2 is its distance from our planet. So if suddenly some kind of malfunction is discovered at the telescope, as was the case with Hubble, it is unlikely that it will be possible to correct it in the coming years - the repair team now simply has nothing to fly on; new generation ships will appear in five years, not earlier.
This forces scientists, designers and testers, who are now bringing the Webb to condition, to be extremely careful. After all, the Webb telescope will operate at a distance 2,500 times greater than that at which Hubble operated, and almost four times the distance of the Moon from the Earth.
The main mirror, with a diameter of 6.6 m, when assembled, will not fit on any of the existing spacecraft. Therefore, it is made up of smaller parts so that it can be easily folded. As a result, the telescope consists of 18 smaller hexagonal mirrors, with a side length of 1.32 m. The mirrors are made of light and durable beryllium metal. Each of the 18 mirrors, plus three backup ones, weighs about 20 kg. As they say, feel the difference between them and the ton that Hubble's 2.4-meter mirror weighs.
The mirrors are ground and polished with an accuracy of 20 nanometers. The starlight will be reflected by the primary mirror onto a secondary mirror mounted above it, which can be automatically adjusted if necessary. Through the hole in the center of the main mirror, the light will be reflected again - this time onto the instruments.
On Earth, the newly polished mirrors are placed in a giant NASA freezer, where space conditions are created - severe cold and vacuum. By reducing the temperature to -250 °C, specialists must ensure that the mirrors take the expected shape. If not, then they will be polished again, trying to achieve the ideal.
The finished mirrors are then gold-plated, since gold reflects infrared heat rays best. Next, the mirrors will be frozen again and will undergo final testing. Then the telescope will be finally assembled and tested not only for the smooth operation of all components, but also for resistance to vibrations and overloads that are inevitable when launching a rocket into space.
Because gold absorbs the blue portion of the visible light spectrum, the Webb telescope will not be able to photograph celestial objects as they appear to the naked eye. But the ultra-sensitive sensors MIRI, NIRCam, NIRSpec and FGS-TFI can detect infrared light with wavelengths from 0.6 to 28 microns, which will make it possible to photograph the first stars and galaxies formed as a result of the Big Bang.
Scientists suggest that the first stars formed several hundred million years after the Big Bang, and then these giants, with radiation millions of times stronger than the sun, exploded as supernovae. You can check whether this is really so only by looking at the very outskirts of the Universe.
However, the new space telescope is intended not only for observing the most distant and, therefore, ancient objects of the Universe. Scientists are also interested in the dusty regions of the galaxy, where new stars are still being born. Infrared radiation can penetrate dust, and thanks to James Webb, astronomers will be able to understand the formation of stars and their accompanying planets.
Scientists hope not only to capture the planets themselves orbiting stars endless light-years away, but also to analyze the light from Earth-like exoplanets to determine the composition of their atmospheres. For example, water vapor and CO2 send specific signals by which it will be possible to determine whether there is life on planets distant from us.
Radioastron is preparing for work. This space telescope had a difficult fate. Work on it began more than ten years ago, but it was still not possible to complete it - there was no money, overcoming certain technical difficulties required more time than initially thought, or there was another break in space launches...
But finally, in July 2011, the Spektr-R satellite with a payload of about 2600 kg, of which 1500 kg was for the drop-down parabolic antenna, and the rest for the electronic complex containing cosmic radiation receivers, amplifiers, control units, signal converters , scientific data transmission system, etc., was launched.
First, the Zenit-2SB launch vehicle and then the Fregat-2SB upper stage launched the satellite into an elongated orbit around the Earth at an altitude of about 340 thousand km.
It would seem that the creators of the equipment from the Lavochkin NPO, together with the chief designer Vladimir Babyshkin, could breathe freely. No such luck!..
“The launch vehicle performed without any problems,” Vladimir Babyshkin said at a press conference. “Then there were two activations of the accelerating block. The orbit of the device is somewhat unusual from the point of view of launch, because there are quite a lot of restrictions that we had to satisfy "...
As a result, both activations of the upper stage took place outside the visibility range of ground stations from Russian territory, and this added excitement to the ground team. Finally, telemetry showed: both the first and second activations went well, all systems worked normally. The solar panels opened, and then the control system kept the device in a given position.
At first, the operation to open the antenna, which consists of 27 petals that were folded during transportation, was scheduled for July 22. The process of opening the petals takes approximately 30 minutes. However, the process did not begin immediately, and the deployment of the radio telescope’s parabolic antenna was completed only on July 23. By autumn, the “umbrella” with a diameter of 10 m was completely opened. “This will make it possible to obtain images, coordinates and angular movements of various objects in the Universe with exceptionally high resolution,” the experts summed up the results of the first stage of the experiment.
After opening the receiving antenna mirror, the space radio telescope takes about three months to synchronize with earth-based radio telescopes. The fact is that it should not work alone, but “in conjunction” with ground-based instruments. It is planned that two hundred-meter radio telescopes in Green Bank, West Virginia, USA, and Effelsberg, Germany, as well as the famous Arecibo radio observatory in Puerto Rico will be used as synchronous radio telescopes on Earth.
Directed simultaneously at the same stellar object, they will work in interferometer mode. That is, to put it simply, with the help of computer information processing methods, the data obtained will be brought together, and the resulting picture will correspond to the one that could be obtained from a radio telescope, the diameter of which would be 340 thousand km larger than the diameter of the Earth.
A ground-space interferometer with such a base will provide conditions for obtaining images, coordinates and angular movements of various objects in the Universe with exceptionally high resolution - from 0.5 milliseconds of arc to several microseconds. “The telescope will have an exceptionally high angular resolution, which will make it possible to obtain previously unattainable in detail images of the space objects being studied,” emphasized RAS Academician Nikolai Kardashev, director of the Academic Space Center of the Lebedev Physical Institute, the lead organization for the complex of scientific equipment of the Radioastron satellite.
By comparison, the resolution that can be achieved using RadioAstron will be at least 250 times higher than that can be achieved using a ground-based network of radio telescopes, and more than 1000 times higher than that of the Hubble Space Telescope operating in optical range.
All this will make it possible to study the surroundings of supermassive black holes in active galaxies, to consider in dynamics the structure of the regions where stars are formed in our Milky Way galaxy; study neutron stars and black holes in our Galaxy; study the structure and distribution of interstellar and interplanetary plasma; build an accurate model of the Earth's gravitational field, as well as carry out many other observations and investigations.
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