What are the windows of the Orion spacecraft made of. NASA cans What shape is the porthole in a spaceship

LATCH, CARVED VENTS, SHUTTERS, FRAMES

The main part of the porthole is, of course, glass. "For space" is used not ordinary glass, but quartz. At the time of Vostok, the choice was not very large - only SK and KV grades were available (the latter is nothing more than fused quartz). Later, many other types of glass were created and tested (KV10S, K-108). They even tried to use SO-120 plexiglass in space. The Americans also know the brand of thermal and shock-resistant glass Vycor.

Glasses of various sizes are used for portholes - from 80 mm to nearly half a meter (490 mm), and recently an eight-hundred-millimeter "glass" has appeared in orbit. We will talk about the external protection of "space windows" ahead, but to protect crew members from harmful effects near ultraviolet radiation, special beam-splitting coatings are applied to the glasses of windows operating with non-stationary installed devices.

The porthole is not only glass. To obtain a durable and functional design, several glasses are inserted into a holder made of aluminum or titanium alloy. For the windows of the "Shuttle" even lithium was used.

To ensure the required level of reliability of glasses in the porthole, several were initially made. In which case, one glass will collapse, and the rest will remain, keeping the ship airtight. Domestic windows on the Soyuz and Vostok had three glasses each (on the Soyuz there is one double-glass, but it is covered by a periscope for most of the flight).

On the Apollo and the Space Shuttle, the “windows” are also mostly three-glass, but the “Mercury” - its “first swallow” - was equipped by the Americans with a four-glass porthole.

Unlike the Soviet ones, the American porthole on the Apollo command module was not a single assembly. One glass worked as part of the shell of the bearing heat-shielding surface, and the other two (in fact, a two-glass porthole) were already part of the pressurized circuit. As a result, such windows were more visual than optical. Actually, given the key role of pilots in the management of the Apollo, such a decision looked quite logical.

On the Apollo lunar cabin, all three windows themselves were single-glass, but they were covered from the outside by an external glass that was not included in the pressurized circuit, and from the inside - by an internal safety plexiglass. More single-glass portholes were subsequently installed at orbital stations, where the load is still less than that of the descent vehicles of spacecraft. And on some spacecraft, for example, on the Soviet interplanetary stations "Mars" of the early 70s, in fact, several portholes (two-glass compositions) were combined in one clip.

When a spacecraft is in orbit, the temperature difference across its surface can be a couple of hundred degrees. The expansion coefficients of glass and metal are, of course, different. So seals are placed between the glass and metal of the clip. In our country, the Research Institute of the rubber industry was engaged in them. The design uses vacuum-resistant rubber. The development of such seals is a difficult task: rubber is a polymer, and cosmic radiation “cuts” polymer molecules into pieces over time, and as a result, “ordinary” rubber simply spreads.

The nose glazing of the Buran cabin. The inner and outer part of the porthole Buran

Upon closer examination, it turns out that the design of domestic and American "windows" differ significantly from each other. Practically all glasses in domestic designs are in the form of a cylinder (naturally, with the exception of the glazing of winged vehicles such as "Buran" or "Spiral"). Accordingly, the cylinder has a side surface that must be specially treated to minimize glare. For this, the reflective surfaces inside the porthole are covered with special enamel, and the side walls of the chambers are sometimes even pasted over with semi-velvet. The glass is sealed with three rubber rings (as they were first called - rubber seals).

The windows of the American Apollo spacecraft had rounded sides, and rubber seals were stretched over them, like a tire on a car wheel.

It will no longer be possible to wipe the glasses inside the porthole with a cloth during the flight, and therefore no debris should categorically get into the chamber (inter-glass space). In addition, the glass should not fog up or freeze. Therefore, before launch, not only tanks are filled at the spacecraft, but also windows - the chamber is filled with especially pure dry nitrogen or dry air. In order to “unload” the glass itself, the pressure in the chamber is provided to be half that in the sealed compartment. Finally, it is desirable that on the inside the surface of the walls of the compartment is not too hot or too cold. To do this, sometimes an internal Plexiglas screen is installed.

The Orion multi-purpose transport spacecraft has been developed by NASA and Lockheed Martin since the mid-2000s and already made its first unmanned test flight in December 2014. With the help of Orion, cargo and astronauts will be launched into space, but that's not all that this ship is capable of. In the future, it is Orion that will have to deliver people to the surface of the Moon and Mars. When creating the ship, its developers used a lot of interesting technologies and new materials, one of which we would like to tell you about today. As astronauts travel towards asteroids, the Moon or Mars, they will have stunning views of space through small windows in the ship's hull. NASA engineers are aiming to make these "windows to space" stronger, lighter, and cheaper to manufacture than previous spacecraft models. In the case of the ISS and the Space Shuttle, the windows were made of laminated glass. In the case of the Orion, for the first time, acrylic plastic will be used, which will significantly improve the integrity of the ship's windows. “Glass window panels have historically been part of the ship's shell, maintaining the necessary pressure inside it and preventing the death of astronauts. Also, the glass should protect the crew as much as possible from the huge temperature when entering the Earth's atmosphere. But the main disadvantage of glass is its structural imperfection. Under heavy load, the strength of glass decreases over time. When flying in space, this weak point can play a cruel joke on the ship, ”says Linda Estes, head of the illuminator subsystems department at NASA. Precisely because glass is not ideal material for portholes, engineers were constantly looking for a more suitable material for this. There are many structurally stable materials in the world, but few are transparent enough to be used in portholes. In the early stages of Orion development, NASA tried to use polycarbonates as a window material, but they did not meet the optical requirements necessary for imaging. high resolution. After that, the engineers switched to acrylic material, which provided the highest transparency and tremendous strength. In the USA, huge aquariums are made of acrylic, which protect their inhabitants from the surrounding environment, potentially dangerous for them, while maintaining enormous water pressure. To date, Orion is equipped with four windows built into the crew module, as well as additional windows in each of the two hatches. Each porthole consists of three panels. The inner panel is made of acrylic, while the other two are still made of glass. It was in this form that Orion had already managed to visit space during the first test flight. During this year, NASA engineers must decide whether they can use two acrylic panels and one glass in the windows. In the coming months, Linda Estes and her team are to perform what they call a "creep test" on acrylic panels. Creep in this case is a slow deformation of a solid body that occurs over time under the influence of a constant load or mechanical stress. Creep is subject to everyone without exception solid bodies both crystalline and amorphous. Acrylic panels will be tested for 270 days under enormous stress. The acrylic windows should make the Orion significantly lighter, and their structural strength eliminates the risk of the windows collapsing due to accidental scratches and other damage. According to NASA engineers, thanks to acrylic panels, they will be able to reduce the weight of the ship by more than 90 kilograms. Reducing the mass will make the launch of the ship into space much cheaper. The transition to acrylic panels will also reduce the cost of building ships like Orion, because acrylic is much cheaper than glass. It will be possible to save about 2 million dollars on windows alone during the construction of one spacecraft. It is possible that in the future glass panels will be completely excluded from the windows, but for now additional thorough tests are needed for this. Taken from hi-news.ru

His first unmanned test flight in December 2014. With the help of Orion, cargo and astronauts will be launched into space, but that's not all that this ship is capable of. In the future, it is Orion that will have to deliver people to the surface of the Moon and Mars. When creating the ship, its developers used a lot of interesting technologies and new materials, one of which we would like to tell you about today.

As astronauts travel towards asteroids, the Moon or Mars, they will have stunning views of space through small windows in the ship's hull. NASA engineers are aiming to make these "windows to space" stronger, lighter, and cheaper to manufacture than previous spacecraft models.

In the case of the ISS and the Space Shuttle, the windows were made of laminated glass. In the case of the Orion, for the first time, acrylic plastic will be used, which will significantly improve the integrity of the ship's windows.

“Glass window panels have historically been part of the ship's shell, maintaining the necessary pressure inside it and preventing the death of astronauts. Also, the glass should protect the crew as much as possible from the huge temperature when entering the Earth's atmosphere. But the main disadvantage of glass is its structural imperfection. Under heavy load, the strength of glass decreases over time. When flying in space, this weak point can play a cruel joke on the ship, ”says Linda Estes, head of the illuminator subsystems department at NASA.

Precisely because glass is not an ideal material for portholes, engineers have been constantly looking for a more suitable material for this. There are many structurally stable materials in the world, but few are transparent enough to be used in portholes.

In the early stages of Orion's development, NASA tried to use polycarbonates as window material, but they did not meet the optical requirements needed to produce high-resolution images. After that, the engineers switched to acrylic material, which provided the highest transparency and tremendous strength. In the USA, huge aquariums are made of acrylic, which protect their inhabitants from the surrounding environment, potentially dangerous for them, while maintaining enormous water pressure.

To date, Orion is equipped with four windows built into the crew module, as well as additional windows in each of the two hatches. Each porthole consists of three panels. The inner panel is made of acrylic, while the other two are still made of glass. It was in this form that Orion had already managed to visit space during the first test flight. During this year, NASA engineers must decide whether they can use two acrylic panels and one glass in the windows.

In the coming months, Linda Estes and her team are to perform what they call a "creep test" on acrylic panels. Creep in this case is a slow deformation of a solid body that occurs over time under the influence of a constant load or mechanical stress. All solids without exception, both crystalline and amorphous, are subject to creep. Acrylic panels will be tested for 270 days under enormous stress.

The acrylic windows should make the Orion significantly lighter, and their structural strength eliminates the risk of the windows collapsing due to accidental scratches and other damage. According to NASA engineers, thanks to acrylic panels, they will be able to reduce the weight of the ship by more than 90 kilograms. Reducing the mass will make the launch of the ship into space much cheaper.

The transition to acrylic panels will also reduce the cost of building ships like Orion, because acrylic is much cheaper than glass. It will be possible to save about 2 million dollars on windows alone during the construction of one spacecraft. It is possible that in the future glass panels will be completely excluded from the windows, but for now additional thorough tests are needed for this.

WE FLY?? ?)) In what city and how are portholes for spaceships made? and got the best answer

Answer from Incognito Mask[guru]
The window of the spacecraft (SC) performs two main functions. First, it must have an appropriate range and level of transmission and reflection of electromagnetic radiation, ensuring the operation of an optical device or visual observation with a minimum of distortion and interference.
Secondly, being a part of the spacecraft envelope, it must, while maintaining integrity, protect the crew and equipment from the effects of factors outer space and the earth's atmosphere.

With long-term operation of windows on board the spacecraft, the probability of its damage increases, on the outer surface of the glasses under the influence of micrometeorites, space dust and debris, craters, gouges, scratches of various sizes and shapes are formed, which raises concerns about the reliability of the product.
The launch of a long-term orbital ISS caused the need to study the long-term strength and durability of optical elements damaged by microparticle impacts during ground-based modeling, analysis and systematization of emerging mechanical defects, scientific and technical substantiation of permissible and critical defects, development of a methodology for examining the state of portholes in orbit, issuing conclusions on performance portholes with defects.
The cockpit of the first spacecraft is much more spacious than a conventional cockpit in an airplane. The device has three
portholes with heat-resistant glass and two quick-opening hatches.

The cabin of the Vostok spacecraft was equipped with three windows (direct and side views), the cabin of the Mercury spacecraft was equipped with only one (in front of the astronaut).
spaceship porthole 7K. Photo 1966
Portholes were manufactured at the Avtosteklo plant in Konstantinovka, Donetsk region. They were in the column "other products". Everything was very secret. They made glass for a wide variety of vehicles, including participating in equipping the first nuclear-powered icebreaker Lenin. Now this enterprise is called CJSC "Spetstechsteklo", it has developed a new multi-layer glazing, launched the production of aviation glass, tempered, multi-layered with a thickness of 6.5-70 mm, armored (II - IV degree).
Innovation in the production of special glasses - the world's largest sapphire has been grown in Ukraine. The process of appearance of this amazing stone took only 10 days - from July 20 to 30. In such a short time, the stone reached simply incredible dimensions: 80 by 35 by 5 cm and a weight of 45 kilograms. From sapphires of a similar size and shape, it will be possible to make portholes for spacecraft that are resistant to external influences.
A source:

Answer from 2 answers[guru]

Hey! Here is a selection of topics with answers to your question: DO WE FLY?? ?)) In what city and how are portholes for spaceships made?

Answer from Alexey Kuznetsov[guru]
I know for sure that for Tereshkova the windows were made in a small town in the Novgorod region - Malaya Vishera, at a local glass factory. The plant is closed, but the veterans commemorate Valya's personal gratitude.

Answer from Marina[guru]
Gus-Khrustalnensky quartz glass factory.
The plant is truly unique. It is the only one in Russia that has the technology and equipment for the production of highly pure quartz products. Without its glasses, a power laser installation will not work, not a single spaceship will enter orbit. Plus radiation-resistant glasses for nuclear power plants, extra pure - for the chemical industry, quartz substrates for computer displays on liquid crystals, optical fiber, glasses for night vision devices, crystalline piezoelectric quartz for mobile and space communications, and much more. At the time of the USSR, it belonged to the building materials industry, the plant almost completely worked for the defense industry.
There are two main specializations. Firstly, the production of crystalline quartz, which is the specialty of workshop No. 5, the one where expensive Japanese equipment is installed. And this is, first of all, piezoquartz, from which resonators for the radio-electronic industry are made. Its price ranges from 50 to 150 dollars per kilogram. And the potential capacity of the workshop is to produce about 240 tons of these crystals per year. And this is 2.5 - 3 million dollars of profit. .
The second direction is fused quartz, from which the very portholes for space stations, substrates for liquid crystal monitors, extra-pure glasses for the chemical industry, optical fibers, etc. are made.
On the verge of death is the Scientific Research Institute of Technical Glass, the country's only developer of portholes for spacecraft, Air Force aircraft and submarines.
IN open space at high temperatures, any glass in the portholes of the ship burns out, and with an increase in its thickness, the possibility of viewing is difficult, since transparency is noticeably reduced. An inorganic nanomaterial coating was applied to the outer side of the porthole without changing the optical properties of the glass itself. The outer shell of the Buran was also coated with heat-resistant ceramic compounds based on nanopowders.
At the factory in Samara.
Creation of portholes for the spacecraft
Portholes with protective glasses that do not transmit cosmic rays. There are also replaceable filters that protect from direct sunlight, and a curtain mechanism in case of excessive exposure or elevated temperatures.
In most cases, the design was developed at GOI, a prototype of each new lens was manufactured and tested, after which the proven technology was introduced at the enterprises of the industry. It should be noted that in those cases when lens developers lacked glasses with the necessary parameters to achieve higher technical or operational characteristics, such glasses were specially developed at Branch No. 1 of the GOI (NITIOM), and the corresponding melting technologies were also introduced. These works were supervised by Academician G. T. Petrovsky, an outstanding scientist and founder of optical, including space, materials science. We mention in particular that under his leadership, research and experiments were also carried out on growing in space conditions high-purity optical crystals with a reduced number of dislocations.

When looking at a spacecraft, the eyes usually run wide. Unlike an aircraft or a submarine with extremely “smooth” contours, a mass of all sorts of blocks, structural elements, pipelines, cables sticks out from the outside ... But there are also details on board that are understandable at first glance to anyone. Here are the portholes, for example. Just like aircraft or sea! In fact, it's far from it...

From the very beginning of space flights, the question was: “What is overboard - it would be nice to see!” That is, of course, there were certain considerations in this regard - astronomers and pioneers of astronautics did their best, not to mention science fiction writers. In Jules Verne's novel "From the Earth to the Moon" the characters go on a lunar expedition in a projectile equipped with shuttered glass windows. Through large windows, the heroes of Tsiolkovsky and Wells look at the Universe.

When it came to practice, the simple word "window" seemed unacceptable to the developers of space technology. Therefore, what the astronauts can look out of the ship through is called, no less, special glazing, and less "ceremonially" - portholes. Moreover, the porthole for people actually is a visual porthole, and for some equipment it is an optical porthole.

Portholes are both a structural element of the spacecraft shell and an optical device. On the one hand, they serve to protect the instruments and the crew inside the compartment from the effects of the external environment, on the other hand, they must ensure the operation of various optical equipment and visual observation. Not only, however, observation - when on both sides of the ocean they drew equipment for "star wars", they were going to take aim through the windows of warships.

Americans and English-speaking rocket scientists in general are confused by the term "porthole". They ask again: “Are these windows, or what?” IN English language everything is simple - what is in the house, what is in the "Shuttle" - window, and no problems. But English sailors say porthole. So Russian space window builders are probably closer in spirit to overseas shipbuilders.

Two types of portholes can be found on observation spacecraft.

The first type completely separates the shooting equipment (lens, cassette part, image sensors and other functional elements) located in the pressurized compartment from the "hostile" external environment. According to this scheme, spacecraft of the Zenit type were built.

The second type of windows separates the cassette part, image sensors and other elements from the external environment, while the lens is in an unpressurized compartment, that is, in a vacuum. Such a scheme is used on spacecraft of the "Yantar" type. With such a scheme, the requirements for the optical properties of the illuminator become especially stringent, since the illuminator is now an integral part of the optical system of the shooting equipment, and not a simple “window into space”.

It was believed that the astronaut would be able to control the ship, based on what he could see. To a certain extent, this has been achieved. It is especially important to “look ahead” during docking and landing on the Moon – there, American astronauts have repeatedly used manual control during landings.

For most astronauts, the psychological idea of up and down is formed depending on the environment, and portholes can also help with this. Finally, portholes, like windows on Earth, serve to illuminate the compartments when flying over the illuminated side of the Earth, the Moon, or distant planets.

Like any optical device, a ship's porthole has a focal length (from half a kilometer to fifty) and many other specific optical parameters.

When creating the first spacecraft in our country, the development of portholes was entrusted to Research Institute of Aviation Glass Minaviaprom(now this JSC Research Institute of Technical Glass). Also involved in the creation of "windows to the Universe" State Optical Institute. S.I. Vavilov, Research Institute of rubber industry, Krasnogorsk Mechanical Plant and a number of other enterprises and organizations. A large contribution to the melting of glasses of various brands, the manufacture of portholes and unique long-focus lenses with a large aperture Lytkarinsky plant of optical glass.

The task turned out to be extremely difficult. The production of aircraft lamps was also mastered at one time for a long and difficult time - the glass quickly lost its transparency, became covered with cracks. In addition to providing transparency, Patriotic War forced the development of armored glass, after the war, the growth of jet aircraft speeds led not only to an increase in strength requirements, but also to the need to preserve the properties of glazing during aerodynamic heating. For space projects, the glass that was used for lanterns and windows of aircraft was not suitable - not the same temperatures and loads.

The first space windows were developed in our country on the basis of the Decree of the Central Committee of the CPSU and the Council of Ministers of the USSR No. 569-264 dated May 22, 1959, which provided for the start of preparations for manned flights. Both in the USSR and in the USA, the first windows were round - they were easier to calculate and manufacture. In addition, domestic ships, as a rule, could be controlled without human intervention, and, accordingly, there was no need for a too good view “by aircraft”. Gagarin's Vostok had two portholes. One was located on the entrance hatch of the descent vehicle, just above the cosmonaut's head, the other was at his feet in the descent vehicle body.

It is not out of place to recall the names of the main developers of the first windows at the Aviation Glass Research Institute - this is S.M. Brekhovskikh, V.I. Aleksandrov, H.E. Serebryannikova, Yu.I. Nechaev, L.A. Kalashnikov, F.T. Vorobyov, E.F. Postolskaya, L.V. King, B.P. Kolgankov, E.I. Tsvetkov, S.V. Volchanov, V.I. Krasin, E.G. Loginova and others.

Due to many reasons, when creating their first spacecraft, our American colleagues experienced a serious "mass deficit". Therefore, they simply could not afford a level of ship control automation similar to the Soviet one, even taking into account lighter electronics, and many ship control functions were limited to experienced test pilots selected for the first cosmonaut detachment. At the same time, in the original version of the first American ship "Mercury" (the one about which they said that the astronaut does not enter it, but puts it on himself), the pilot's window was not provided at all - there was nowhere to take even the required 10 kg of additional mass.

The porthole appeared only at the urgent request of the astronauts themselves after the first flight of Shepard. A real, full-fledged "pilot" porthole appeared only on the "Gemini" - on the crew's landing hatch. But it was made not round, but of a complex trapezoidal shape, since for full manual control when docking, the pilot needed a forward view; on the Soyuz, by the way, for this purpose, a periscope was installed on the porthole of the descent vehicle. The development of windows for the Americans was carried out by Corning, a division of JDSU was responsible for the coatings on the glasses.

On the command module of the lunar Apollo, one of the five windows was also placed on the hatch. The other two, providing rendezvous when docking with lunar module, looked forward, and two more "lateral" ones allowed them to glance perpendicular to the longitudinal axis of the ship. On the Soyuz, there were usually three windows on the descent vehicle and up to five on the amenity compartment. Most windows at orbital stations - up to several dozen, different forms and sizes.

An important step in the "window construction" was the creation of glazing for space planes - "Space Shuttle" and "Buran". The "shuttles" are planted like an airplane, which means that the pilot must be provided good review from the cab. Therefore, both American and domestic developers have provided for six large portholes of complex shape. Plus, a pair in the cabin roof - this is already to ensure docking. Plus windows in the rear of the cab - for payload operations. And finally, through the porthole on the entrance hatch.

In the dynamic phases of the flight, the forward windows of the Shuttle or Buran are subjected to completely different loads, different from those to which the windows of conventional descent vehicles are subject. Therefore, the calculation of strength is different here. And when the "shuttle" is already in orbit, there are "too many" windows - the cabin overheats, the crew receives an extra "ultraviolet". Therefore, during an orbital flight, part of the windows in the Shuttle cabin are closed with Kevlar shutters. But the Buran had a photochromic layer inside the windows, which darkened under the action of ultraviolet radiation and did not let the “extra” into the cockpit.

Glasses of various sizes are used for portholes - from 80 mm to nearly half a meter (490 mm), and recently an eight-hundred-millimeter "glass" has appeared in orbit. We will talk about the external protection of "space windows" ahead, but to protect crew members from the harmful effects of near ultraviolet radiation, special beam-splitting coatings are applied to the glasses of windows working with non-stationary installed devices.

On the Apollo and the Space Shuttle, the “windows” are also mostly three-glass, but the Mercury, their “first swallow,” was equipped by the Americans with a four-glass porthole.

On the Apollo lunar cabin, all three windows themselves were single-glass, but on the outside they were covered by an external glass that was not included in the pressurized circuit, and from the inside - by an internal safety plexiglass. More single-glass portholes were subsequently installed at orbital stations, where the load is still less than that of the descent vehicles of spacecraft. And on some spacecraft, for example, on the Soviet interplanetary stations "Mars" of the early 70s, in fact, several portholes (two-glass compositions) were combined in one clip.

The windows of the American Apollo spacecraft had rounded sides, and rubber seals were stretched over them, like a tire on a car wheel.

Glass is not metal, it breaks down differently. There will be no dents here - a crack will appear. The strength of glass depends mainly on the condition of its surface. Therefore, it is strengthened, eliminating surface defects - microcracks, cuts, scratches. To do this, the glass is etched, tempered. However, glasses used in optical instruments are not treated this way. Their surface is hardened during the so-called deep grinding. By the beginning of the 70s, the outer glasses of optical windows had learned to harden ion exchange which made it possible to increase their abrasion resistance.

To improve light transmission, the glass is coated with a multilayer antireflection coating. They may include tin oxide or indium oxide. Such coatings increase light transmission by 10–12%, and they are applied by reactive cathode sputtering. In addition, indium oxide absorbs neutrons well, which is useful, for example, during a manned interplanetary flight. In general, indium is the "philosopher's stone" of the glass industry, and not only of the glass industry. Indium-coated mirrors reflect most of the spectrum in the same way. In rubbing knots, indium significantly improves abrasion resistance.

In flight, windows can become dirty from the outside. Already after the start of flights under the Gemini program, the astronauts noticed that evaporation from the heat-shielding coating was deposited on the glass. Spacecraft in flight generally acquire the so-called accompanying atmosphere. Something is leaking from the pressurized compartments, small particles of screen-vacuum thermal insulation “hang” next to the ship, right there are combustion products of fuel components during the operation of orientation engines ... In general, there is more than enough garbage and dirt to not only “spoil view”, but also, for example, disrupt the operation of on-board photographic equipment.

Developers of interplanetary space stations from NPO them. C.A. Lavochkin they say that during the flight of a spacecraft to one of the comets, two “heads” - nuclei were found in its composition. It was considered important scientific discovery. Then it turned out that the second "head" appeared due to fogging of the porthole, which led to the effect of an optical prism.

Porthole glasses should not change light transmission when exposed to ionizing radiation from background cosmic radiation and cosmic radiation, including as a result of solar flares.

The interaction of electromagnetic radiation from the Sun and cosmic rays with glass is a complex phenomenon in general. The absorption of radiation by glass can lead to the formation of so-called "color centers", that is, to a decrease in the initial light transmission, and also cause luminescence, since part of the absorbed energy can immediately be released in the form of light quanta.

The luminescence of the glass creates an additional background, which reduces the contrast of the image, increases the noise-to-signal ratio, and may make it impossible for the equipment to function normally. Therefore, glasses used in optical windows must have, along with high radiation-optical stability, low level luminescence. The magnitude of the luminescence intensity is no less important for optical glasses operating under the influence of radiation than the resistance to staining.

Among the factors of space flight, one of the most dangerous for windows is micrometeor impact. It leads to a rapid drop in the strength of the glass. Its optical characteristics also deteriorate.

Already after the first year of flight, craters and scratches reaching one and a half millimeters are found on the outer surfaces of long-term orbital stations. If most of the surface can be shielded from meteor and man-made particles, then windows cannot be protected in this way.

To a certain extent, they are saved by lens hoods, sometimes installed on windows through which, for example, on-board cameras work. At the first American orbital station Skylab, it was assumed that the windows would be partly shielded by structural elements. But, of course, the most radical and reliable solution is to cover the windows of the "orbital" with controlled covers from the outside. Such a solution was applied, in particular, at the second-generation Soviet orbital station Salyut-7.

"Garbage" in orbit is becoming more and more. In one of the flights of the Shuttle, something clearly man-made left a rather noticeable pothole-crater on one of the windows. The glass survived, but who knows what might come next?.. By the way, this is one of the reasons for the serious concern of the "space community" about the problems of space debris. In our country, the problems of micrometeorite impact on structural elements spacecraft, including the portholes, is actively involved, in particular, Professor Samara State Aerospace University L.G. Lukashev.

In even more difficult conditions, the windows of the descent vehicles operate. When descending into the atmosphere, they find themselves in a cloud of high-temperature plasma. In addition to pressure from inside the compartment, external pressure acts on the porthole during descent. And then comes the landing - often on the snow, sometimes in the water. In this case, the glass is rapidly cooled. Therefore, here the issues of strength are given special attention.

"The simplicity of the porthole–it is an apparent phenomenon. Some opticians say that creating a flat porthole–the task is more complicated than the manufacture of a spherical lens, since it is much more difficult to build an “exact infinity” mechanism than a mechanism with a finite radius, that is, a spherical surface. And, nevertheless, there have never been any problems with the windows, ”- this is probably the best assessment for the spacecraft node, especially if it came from the mouth George Fomin, in the recent past - the first deputy general designer of the GNPRKTs "TsSKB - Progress".

Not so long ago - February 8, 2010 after the flight of the "Shuttle" STS-130 - at the International space station an observation dome appeared, consisting of several large quadrangular windows and a round 800 mm porthole.

The Cupola module is designed for Earth observations and work with a manipulator. It was developed by the European concern Thales Alenia Space, and was built by Italian machine builders in Turin.

Thus, today the Europeans hold the record - such large windows have not yet been put into orbit either in the USA or in Russia. The developers of various "space hotels" of the future also talk about huge windows, insisting on their special significance for future space tourists. So "window construction" has a great future, and windows continue to be one of the key elements of manned and unmanned spacecraft.

"Dome"–really cool stuff! When you look at the Earth from the porthole, it's the same as through an embrasure. And in the "dome" a 360-degree view, you can see everything! The earth from here looks like a map, yes, most of all it resembles geographical map. You can see how the sun leaves, how it rises, how the night approaches ... You look at all this beauty with some kind of fading inside.

From the diary of cosmonaut Maxim Suraev.