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None of the astronomical Yearbook of the world you will not find mention of solar eclipses, 1975. This year they are simply not there. Nevertheless, modern space has made adjustments. During the joint flight of space ships Soyuz and Apollo in July 1975, cosmonauts Alexei Leonov and Valery Kubasov together with astronauts Thomas Stafford, Vance brand and Donald Slayton spent one of the fundamental Soviet-American experiments in "Artificial solar Eclipse". This is the first solar Eclipse, created by man.

The experiment and its methodology was proposed by Soviet scientists, Gennady Nikolsky and Anatoly Simonov. About how it was prepared and the experiment was conducted and what results were obtained, says one of its authors — A. Simonov.

The Soviet-American program EPAS aroused great interest in the scientific world: I had an opportunity to conduct research during the joint flight of two spacecraft. The organizers received many interesting proposals from scientists around the world. Soviet-American Commission selected five joint experiments, one of which was called "Artificial solar Eclipse".

The experiment consisted of the following: the ship "Apollo" has created an artificial solar Eclipse and Board the Soyuz spacecraft has been photographing the outer corona and "atmosphere" around the Apollo during the Eclipse. But this does not exhaust the tasks of the experiment. He was primarily a test of new methods of research: possibilities for modeling of solar eclipses in the conditions of orbital flight and the mutual influence of two objects of the study of the solar corona and a private atmosphere shading of the spacecraft.

Why you need to study a solar Eclipse?

Corona is the most external, extremely rarefied layers of the solar atmosphere and consists of almost fully ionized hydrogen plasma of protons and electrons with a temperature of 1-2 million degrees. The content of other elements

does not exceed 10%. In fact, the solar corona is a continuous flow of matter coming from the Sun, or as it is called, the solar wind that extends far beyond the orbit of the Earth.

In the crown of the formed particles of high energy and electromagnetic radiation. In the visible region of the spectrum she finds herself in a faint glow that represents sunlight scattered by electrons Corot-tional plasma (protons scatter light weakly).

Own radiation of the corona due to high temperature falls in the invisible region of the spectrum, mainly on shortwave.

Its brightness a million times weaker than the solar disk, and to see it from Earth only during total solar eclipses when the sky brightness is reduced in tens of thousands of times. It is this happy circumstance allowed us to detect the solar corona in ancient times. However, its physical nature is beginning to emerge only in the last decade.

What else is artificial?

Total solar Eclipse is an exceedingly rare occurrence. In the same geographic location it is observed on average once every 200-300 years and often for one or two minutes. In the entire history of instrumental observations of the total solar Eclipse total time of these observations does not exceed two hours. However, even for such a short time was made the most important discoveries in astrophysics, and Geophysics. However, now the crown can be studied outside of Eclipse, e.g., in the shortwave range with missiles and satellites. Nevertheless, for a number of reasons to obtain full and reliable information only such methods impossible. The only way vestmanna observations of the solar corona in the visible region of the spectrum, creating an artificial solar Eclipse. This principle underlies the so-called vestmanna of coronographs where artificial Eclipse is realized in the instrument: image of the solar disk is covered with an opaque screen. On Earth because of the high brightness of atmospheric background to observe the crown with the help of coronagraphs possible only at the very edge of the solar disk.

Relatively recently (in 1964) appeared more sophisticated vestmanna coronography, but these devices are not much extend the possibilities of research. Even on the space station "Skylab" by using such a coronagraph could be seen the crown only within 1° from the edge of the solar disk. The disadvantage of all cronografo — the presence of the chromatic aberration of the lens, so as to reduce light scattering they are made with a single lens. So the Eclipse is obtained only in a narrow spectral range.

Thus, the coronagraph can be used only for studies of the inner parts of the crown.

In the experiment, the same "Artificial solar Eclipse" can create the conditions for exploration of the outer crown (at large angular distances from the solar disk). First, there are no nuisance observations highlights from Earth and diffraction at the edges of the artificial moon. And secondly, because "Union" is in the shadow of Apollo, the private atmosphere of our ship does not affect the observation. Under these conditions, scientists use a more simple and compact instrument that allows you to observe in the whole spectral range, as if it were a natural solar Eclipse.

Private atmosphere of the spacecraft

Another object of study in the experiment "Artificial solar Eclipse" — private atmosphere of the spacecraft, or if you want aura. What is this aura and why it has attracted the attention of scientists?

From the surface of a spacecraft in the vacuum of space, there is a continuous evaporation of different materials. In the first place it leave it of adsorbed gases, water and other volatile substances. Then break off the macroscopic education — "dust" — as the old-timers from Earth, and again born as a result of destruction of the coatings. The process of destruction affects all materials. Micrometeorite particles, cosmic and solar radiation exacerbate this process.

Products "wear" not immediately leave the surroundings of the vehicle first, they form around it a special atmosphere. The atmosphere is continuously replenished by the inevitable leakage of cabin gas through the walls and seals, but especially big contribution to it make the exhaust products of jet engines.

In the orbital flight for dust atmosphere created by the spacecraft, exposed to the incoming flow of the residual of the Earth's atmosphere, sunlight pressure and solar wind. The result is a space ship becomes like a comet. And this is not a figurative comparison! Although the spacecraft is surrounded by an extremely tenuous atmosphere, yet it differs from the unperturbed space environment. As you know, the atmospheric density of the comet is also negligible. Thus, monitoring is conducted as if the "inside" of the comet.

The materials of the "atmosphere" change the physical characteristics of the environment and, therefore, can have feedback effects on vital systems of the spacecraft and even distort the scientific information. Because its the main volume obtained with the aid of optical means, it is very important to investigate the optical characteristics of the environment change under the effect of the atmosphere of the spacecraft (the distortion of the light signal, errors in readings due to them settled on "dust").

Still it was only about physical perturbations of the environment. In this sense, and used the concept of "private atmosphere". In reality, spacecraft, as with any body, alters the totality of the physical parameters of the environment: and plasma, gravitational, and electromagnetic and radiation fields. The result is a local violation of "ecology", and there are physical processes, not typical of the unperturbed space environment. Therefore, a transition region between the spacecraft and the unperturbed environment could be seen as a physical aura, a special case of which is the private atmosphere of the ship.

In the experiment "Artificial solar Eclipse" for the first time had the opportunity to see the face of the aura — a luminous halo around one of the spacecraft.

What could be easier than doing Eclipse?

The idea of the experiment is extremely simple. But for its implementation in the conditions of orbital flight required high precision piloting technique and the consistency of the actions of the crews of both ships, as well as a clear work of experts of two continents.

Prior to undocking a bunch of spacecraft "Soyuz" — "Apollo" oriented longitudinal axis in the Sun and in this position stabilize. At noon universal time divided the ships, keeping the position of their axes in space. The relative speed was approximately 1 m/s along the line of the Sun — ships. Making a reciprocating movement along the orbit, the spacecraft is gradually diverged along the line. The "Apollo" were covering the Sun, creating for observers on Board of the "Union" conditions of artificial solar Eclipse. The divergence continued up to 220 m. At this distance, to observers on the spacecraft "Soyuz" angular dimensions of the artificial moon ("Apollo"), only half exceeded the size of the solar disk. Then the movement of ships along the line of the Sun — Apollo — Soyuz was reversed for re-docking.

To exclude the illumination of the Earth working window of the "Union" and visible part of the "Apollo" (artificial Moon should be dark), the experiment was carried out on the section of the orbit from the rising of the Sun to the ships crossing the plane of the terminator (plane passing through the border of day and night on Earth). On the Ground in a night, and for ships the Sun has risen. Scheme and time sequence of events of the experiment are shown in the figure.

During the artificial solar Eclipse through the window of the Soyuz spacecraft automatic camera were photographing the solar corona and "atmosphere" around the ship "Apollo". Simultaneously, the crew of "Apollo" was done filming the "Union."

At a time when cosmonauts and astronauts flying over Tierra del Fuego and the Straits of Magellan, creating a solar Eclipse on Earth their work was watched by thousands of professionals: two flight control center, command-measuring complexes, with multiple ships and aircraft, dispersed around the globe. At the same time on Elbrus a group of astrophysicists conducted simultaneous observations of the Sun.

The main results

The terms solar Eclipse be retained for at least seven minutes. In the course of the experiment exhibited more than a hundred frames. The obtained image of the outer solar corona in the form of weak diffuse emission. Almost all footage seen three astronomical object: the planet mercury and the star α γ Twins and Small Dog. Noticeable bright narrow ring surrounding Apollo, is the diffraction of sunlight on the edge. All footage seen private atmosphere of the ship "Apollo". The exhaust of the jet can be traced up to 50 m.

Thus, in just a few minutes of flight time obtained unique data on the outer solar corona and "atmosphere" around the spacecraft. Photometrically calibrated photographs are not just pictures. They display a sort of totodile huge amount of quantitative data and functional dependencies.

The crucial result of the experiment "Artificial solar Eclipse" can be considered a confirmation of the effectiveness of the new method of the study of the solar corona and atmosphere around the spacecraft.

Translated by «Yandex.Translator»