Dust is interplanetary, at least in comparative proximity to the Earth - the matter is rather studied. Filling all the space of the Solar system and concentrated in the plane of its equator, it was born mostly as a result of accidental collisions of asteroids and the destruction of comets approaching the Sun. The composition of dust, in fact, does not differ from the composition of meteorites falling on the Earth: it is very interesting to study it, and discoveries in this area have to be made a lot, but there seems to be no particular intrigue here. But thanks to this dust in good weather in the west immediately after sunset or in the east before sunrise it is possible to admire a pale cone of light over the horizon. This is the so-called zodiacal - sunlight scattered by fine cosmic dust.
Dust in astronomy is called small, fractional micron-sized solid particles flying in space. Space dust is often conventionally divided into interplanetary and interstellar, although interstellar entry into interplanetary space is not prohibited. It is not easy to find it there, among the "local" dust, the probability is low, and its properties near the Sun may change significantly. If you fly farther away to the boundaries of the solar system, there is a high probability of catching real interstellar dust. The ideal option is to go beyond the limits of the system at all.
Between the stars and the planets
Much more interesting is the interstellar dust. Its distinctive feature is the presence of a solid core and shell. The core seems to consist mainly of carbon, silicon, and metals. And the shell is mainly made up of gaseous elements frozen on the surface of the core, crystallized under conditions of "deep-freezing" of interstellar space, which is about 10 kelvins, hydrogen, and oxygen. However, there are even more complex impurities of molecules in it. These are ammonia, methane and even multi-atomic organic molecules that stick to the dust or form on its surface during wanderings. Some of these substances, of course, fly off its surface, for example, under the influence of ultraviolet light, but the process is reversible - some fly away, others freeze or synthesize.
Now, in the space between the stars or near them have already been found, of course, not chemical, but physical, that is, spectroscopic, methods: water, carbon monoxides, nitrogen, sulfur and silicon, hydrogen chloride, ammonia, acetylene, organic acids such as ants and acetic, ethyl and methyl alcohols, benzene, naphthalene. Even glycine amino acid was found!
Of course, one can study the properties of interstellar dust from a distance with the help of telescopes and other devices located on the Earth or its satellites. But it is more tempting to catch interstellar dust particles, and then to study them in detail, to find out - not theoretically, but practically, what they consist of, how they are arranged. There are two variants here. It is possible to get to the cosmic depths, to accumulate interstellar dust there, to bring it to Earth and to analyze it in all possible ways. And you can try to fly out of the solar system and on the way to analyze the dust directly on board the spacecraft, sending the received data to Earth.
Dust Hunt
The first attempt to bring samples of interstellar dust, and in general, substances of interstellar environment, several years ago was undertaken by NASA. The spacecraft was equipped with special traps - collectors for collecting interstellar dust and space wind particles. To catch the dust particles without losing their shell, the traps were filled with a special substance - the so-called aerogel. This very light foamy substance (whose composition is a commercial secret) resembles jelly. Once in it, the dust gets stuck, and then, as in any trap, the lid shuts down to be open on Earth.
This project was called Stardust - Stardust. The program is grandiose. After the start in February 1999, the equipment on board it should eventually collect samples of interstellar dust and separately - dust near comet Wild-2, which flew near the Earth in February last year. Now, with containers filled with this precious cargo, the ship is flying home to land on January 15, 2006, in Utah, near Salt Lake City (USA). That's when astronomers will finally see with their own eyes (with the help of a microscope, of course) the very same dust particles, the models of composition and structure of which they have already predicted.
And in August 2001, Genesis flew for samples of substances from deep space. This NASA project was aimed mainly at catching solar wind particles. After spending 1,127 days in space, for which he flew about 32 million km, the ship returned and dropped to Earth capsule with the resulting samples - traps with ions, particles of solar wind. Alas, there was an unfortunate accident - the parachute did not open, and the capsule from all over the fly was slipped against the ground. And crashed.
In Houston, program participant Don Barnetti said that four solar wind collectors were not damaged, and scientists are actively studying them in Houston.