Specialized satellites with UV telescopes onboard have been operating in near-Earth orbits for more than 20 years, carrying out astronomical observations. Their instruments have achieved high resolution and perfection. This has made it possible to solve many problems in modern astrophysics.
UV radiation plays an important role in the existence of biological life, including human life, and in the entire complex of processes of evolution of the universe. To study what is happening in the depths of space and how it is organized is an interesting task and an eternal goal of mankind. Solving this task, people come across fundamental natural limitations, overcome them and look for new approaches to further advance on the path of knowledge. One of the obstacles to astronomical observations is the opacity of the atmosphere.
The Earth's atmosphere practically does not allow the entire UV section of the electromagnetic spectrum to pass through. However, it is in the ultraviolet range that the wavelengths of the spectral lines corresponding to the most important in astrophysics atomic and molecular hydrogen and deuterium transitions lie. There are also many resonant lines of most of the elements, usually corresponding to the most common state of the atoms. Due to the opacity of the atmosphere, the ultraviolet radiation of celestial objects can only be studied from space. The atmosphere does not interfere with space telescopes. Therefore it is possible to receive the image of objects in the Universe with extremely high angular permission and sharply to increase penetrating force of a telescope.
Ultraviolet
The Universe is studied in the ultraviolet range by special spacecraft. Dozens of space experiments have already been carried out and several projects are under development. It is important to keep track of the development trends in this field of science, and, of course, it is necessary to participate in promising projects. For Russia, which had good traditions here, it is important not to lose them. Especially in times of crisis, when it is necessary to look for various ways of preserving high domestic technology, intellectual and scientific-technical potential, and ultimately strengthening the thawing authority of a developed country
The ultraviolet portion of the electromagnetic spectrum is very wide and potentially much more informative than the optical one. It is impossible to create an effective universal instrument covering this entire range. Therefore, astronomical instruments are created that work in selected parts of the spectrum. Choose in each case the suitable optical scheme of a telescope, technology of manufacturing of reflecting surfaces. Spectrum-UV Observatory is one of the world's largest projects of extra-atmospheric astronomy. Its implementation will make it possible to carry out observations with high and even record resolution in the poorly studied, though very "rich" lines of the spectrum with the time of continuous exposure up to 30 hours. In some cases, the exposure can reach up to 140 hours at high spatial and spectral resolution.
The composition of the spacecraft
The spacecraft "Spectrum-UV" includes a service module, which is standard for all scientific satellites of the series "Spectrum", telescope T-170 and a compartment with a complex of scientific equipment.
Observation conditions impose strict requirements on the parameters of instrument guidance and stabilization. Therefore, the spacecraft is equipped with a spatial orientation control system as a primary contour and a precision guidance system for the T-170 telescope - secondary contour. The primary contour ensures the telescope's pre-positioning with an accuracy of 1-2 ¢ Then the image of the object is brought to the specified position with higher accuracy and is stabilized. In the secondary contour, small telescope optical axis offsets are compensated by the tilting of the secondary mirror. This makes it possible to achieve very high stabilization accuracy - about 0.1 ¢ ¢ A prototype of such a system's complexity has proved its efficiency during the flight of the Astron observatory.
The orbit for the Spectrum-UV satellite was chosen taking into account the fact that the telescope should operate at a long distance from a strong light source - the ground, and its parameters should be stable. It is also important that the spacecraft does not cross the near-Earth radiation belts that affect the operation of many instruments, in addition, the orbital parameters should be consistent with the objectives of launching the observatory, and the satellite should be observed at the maximum time. As the calculations performed at the Institute of Astronomy of RAI have shown, such conditions are satisfied by a strongly elongated orbit with the following initial characteristics: apogee height - 300000 km, perigee height - 500 km, inclination - 51.5 ° and a period of 7 days. Within 8 months after the launch, the orbital height changes and becomes operational - 250000 x 40000 km, which will allow the spacecraft to be constantly out of radiation belts.
The telescope will be able to study all stages of star formation and planetary systems from massive shells around protostars to proplanetary disks around young stars of the main sequence. He will be able to observe the planets like Jupiter in all single stars at distances up to 8 pc, to get the first direct images and spectrograms of extrasolar planets. Many technical solutions № 6 ST and technologies (ultra-light active cryogenic optics, devices to recognize the shape and correct the wavefront of radiation, large-format highly sensitive infrared detectors, ultra-light solar screens) can be used in science and industry in the near future.