Giant Telescope to see clearly in grams – BBC

The unique operation that returned the largest Russian vision telescope, said researcher of the Special Astrophysical Observatory of the Russian Academy of Sciences Yevgeny Semenko.

This summer in Las Campanas Observatory which is located in the center of Chile, was officially launched construction of a huge telescope GMT (Giant Magellanic Telescope – Magellanovsky giant telescope), which in a few years is destined to enter the three largest ground-based telescopes in the world. With it, scientists will have unprecedented opportunities for astronomical observations. It will consist of seven mirrors folded into one common mirror diameter of 25 meters.

The construction started as soon as the 11 partners from different countries managed to collect half of the pledged in the budget of $ 1 billion.

The leader of the size of the primary mirror in the coming years will be E -ELT (Extremely Large Telescope – very large telescope) with a primary mirror diameter of 39 meters, construction of which is began a year ago, in the Chilean Atacama Desert.
This project implements the European Southern Observatory (ESO), which comprises 15 countries: Austria, Belgium, Brazil, Britain, Germany, Denmark, Spain, Italy, the Netherlands, Portugal, Finland, France, Czech Republic, Sweden and Switzerland .

A month ago, ESO signed an agreement with the French optical company Reosc contract for the supply of deformable mirrors for the telescope under construction. They will be used at the heart of the world’s largest system of adaptive optics – a set of movable mirrors to offset shake the atmosphere, improving image quality.

Russia is still on the side of the race: the largest domestic telescope SAO (Special Astrophysical Observatory of the Russian Academy of Sciences), built in 1975, has a mirror diameter of 6 m, and Russia itself is in no hurry to join the European Southern Observatory, although talk about it being a long time and at the highest level.

«In this Observatory SAO work Astrophysics Observer world level. One of the spectral instruments (called SCORPIO), created in the observatory, not inferior to the best world standards. Our astrophysicists can watch the stars on this unit value of 23 minutes. This is a very difficult task: it is accessible only to the most powerful telescopes in places with excellent astronomical climate, “- said in a recent interview,” Gazeta.ru “head of the laboratory of physics of stars SAO Sergei Factory.

A few days ago on the telescope BTA has completed an important procedure that allows to recover the reflectance of the main mirror – aluminizing.

Spray mirror BTA held around every ten years, for this mirror does not leave the tower, and removed and transferred to a vacuum system aluminized mirrors (Voisin).

On the spraying mirror, as well as fiber-optic upgrade Link Ministry of Education has allocated 58 million rubles.

On how unique operation took place, told her direct party to a senior researcher at the Laboratory of stellar magnetism SAO Semenko Evgeniy:

– Today we can say that the operation restoration of our BTA was successful. Aluminizing was performed successfully and the first try.

It is important that this time the entire process of renovation of the reflective layer 6-meter mirror for the first time was carried out exclusively by the staff of the Observatory without the involvement of outside experts.

The sequence of work was as follows. More on working telescope preparations were made for the removal of the primary mirror with a frame. And on July 6 telescope was stopped, and the same day the mirror shot was delivered to the washing room tower BTA. In the following days with the mirror chemical method has been drained the old layer of aluminum, its surface has been thoroughly cleaned and dried. On the perimeter of the mirror elements have been installed O-ring, as during aluminizing the mirror serves as the lower chamber lid Voisin-6.

The camera itself is a vacuum evaporator aluminum. “Fog” from aluminum vapor after settling forms a working layer on the surface of the glass substrate of the mirror. The thickness of this layer – about 0.5 micrometer (or 500 nm).

On the whole procedure of this time was spent around 80 grams of metal, of which the mirror layer took only of about 35 g.

The procedure of evaporation rather short, it takes much more time training. In the procedure for updating foreign telescopes reflecting layer usually takes from several days to a couple of weeks. Some mirrors update continuously. In our case, because of the large gap between the aluminizing and based on their strength has been allocated for a month.

After spraying the mirror layer above it is necessary to conduct a series of procedures to secure the outcome before the mirror returns to the telescope. All these works are carried out in the washing room, which to them properly prepared.

After the delivery of a mirror in a clean, he should be taken off the elements and structures that have been used in the previous stages. Securing is carried out chemically by the oxidation of aluminum with formation of fresh solid but transparent aluminum oxide layer Al2O3. This layer although worse than others (eg. SiO2), but still protects the aluminum from further oxidation rapid. In this case, the mirror bottled special “liquid GOI.”

After four minutes the golden solution should be washed off with water – first routine, and after, and distilled. Next, compressed air is dried and a mirror mounted on the telescope tube.

For August 5, BTA will continue to work normally, bringing scientific results. According to the first estimates, the reflectance of the mirror after spraying has increased by 10-15%.