Translated material
Telescope "James Webb"
December 25 at 12:20 UTC from the Cosmodrome Kuru in French Guiana started the arian-5 launch vehicle with the James Webb space infrared telescope on board (James Webb Space Telescope (JWST). The long -awaited apparatus successfully entered orbit and 27 minutes after the start was plucked from the second step of the rocket [ 1 ], in order to independently continue its way to the L2 L2 L2 point - the Sun, located 1.5 million km from the Earth from the Earth from the Sun. The largest cosmic telescope in history will remain on the so-called gallo-orbit in this point, making oscillatory movements around it [ 2 ]. There are several more scientific devices nearby, for example, the Russian X-ray telescope Spectr-RG and the European astrometric GAIA.
The whole path of “James Webb” to the working orbit can be traced on the NASA website containing detailed infographics about the path completed, performed operations for the deployment of a telescope, temperature on the solar and “shadow” side of the spacecraft [ 3 ].
On the first day of the flight, the solar panel of the power supply system and the antenna of communication were disclosed, as well as the first correction of the flight path. On December 27, the second of the three planned trajectory corrections was made.
By January 4, the sunscreen was completely disclosed, consisting of five layers of thin film covered with aluminum of the capet. At the same time, the main mirror was pushed away from the heat -shielding screen by 1.5 m using a telescopic support tower from composite material. These operations made it possible to divide the space telescope into two parts: cold shadow, where the telescope with scientific instruments is located, and “hot”, constantly lit by the sun, where the main satellite platform with on -board systems, fuel tanks, engines, solar panel and land communication system. Using the system of orientation of the apparatus, the telescope mirrors until the end of the James Webb will be in the shade to provide a low temperature of about 40 K, necessary for the performance of scientific tasks.
On January 5, a tripod with a secondary mirror was opened, on January 7–8 - two wings of the main mirror of the telescope. The next two weeks will go to set up each of the 18 segments of the main mirror and a second mirror using many micromechanical drives. By the end of January, the telescope will be in a working orbit, where it will wait for cooling to the desired temperatures and will calibrate scientific equipment. Work on the scientific program will begin in the summer of 2022. Details about all the remaining operations of the James Webba withdrawal to the Laganga Point L2 are contained in a special blog on the NASA website [ 4 ].
The main mirror with a diameter of 6.5 m, consisting of 18 hexagonal individual segments, as well as the secondary and tertiary mirrors of JWST, are made of rare metal metal, which has the necessary properties for working in space: it is light, durable and with suitable thermal conductivity [ 5 ]. A gold coating with a thickness of 100 Nm is applied to mirrors from beryllia to better reflect infrared radiation, and on top of it - the protective layer of amorphous silicon dioxide.
It was because of the size of the main mirror that the European ARIane-5 launch vehicle was chosen; Even in a partially folded state, it required the use of the largest fairing available on modern reliable space missiles.
Behind the main mirror, a block of scientific equipment is installed, which includes four devices with a working range of wavelengths from 0.6 to 28 microns [ 6 ]:
- NIRCAM (USA) - a camera of visible and near infrared range;
- NIRSPEC (Europe) - spectrograph of the visible and near infrared range;
- NIRISS (Canada) is a camera and a best -case spectrograph. The device includes a sensor of accurate guidance of the FGS telescope;
- Miri (USA and Europe) - camera and spectrograph of the average infrared range. Miri will additionally cool to a temperature of 7 to a helium cryocooler.
The main goal of the James Webb telescope will be the observation of the formation of the very first stars and galaxies. This happened about 13.5 billion years ago. Due to the red displacement caused by the expansion of the universe, ultraviolet radiation and visible light, coming from the first luminous objects, reach us in the infrared range. Therefore, sometimes this telescope is also called a figurative “time machine”. Scientists will be able to observe the young universe, find the first galaxies and stars formed after a large explosion.
James Webb will observe previously open exoplanets to obtain data on the chemical composition of their atmospheres. The solar system will not be deprived of attention: the telescope will allow a new way, with unprecedented permission and sensitivity, look at the planets, their satellites, at transneptunal objects.
The development of the James Webb telescope began in 1996. Over 25 years, its concept and design have changed many times, launch time has shifted, the cost grew, having reached $ 10 billion by 2021. But the discoveries that it can give to humanity should justify all expenses and a long expectation. Due to the accuracy of excretion on the Ariane-5 missile, the fuel was saved, which is necessary to orient the apparatus-to cover the telescope from the sun and at the same time effectively substitute the light of the solar panel, as well as maintain a stable gallo-orbit around the L2 lagrange point. The remaining supply of fuel should be enough for ten years of work. Let's hope that it is very fruitful.
Alexander Khokhlov,
Cosmonautics popularizer, member of the North-West Organization of the Cosmonautics Federation of the Russian Federation
Photo NASA
1. JWST.NASA.GOV/Content/webblaunch/deploymentExplorer.html
2. JWST.NASA.GOV/Content/about/orbit.html
3. Jwst.nasa.gov/content/webblaunch/whereiswebb.html
4. Blogs.nasa.gov/weg/category/James-webb-space-telescope/
5. Phys.org/news/2011–01-space-telescope-bryllium-mirrors.html