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June 20, 2021
Comets, according to scientists, retained in their composition the primary matter in which it was found during the formation of the solar system 4.5 billion years ago. The cometary matter, consisting of primary stardust, is possibly a relic of the earliest stage in the development of the solar system. Therefore, for a comprehensive study of cometary matter, NASA developed a special program in 1995.
The object of research was the short-period comet Wild 2 (81P / Wild), discovered by the Swiss astronomer Paul Wild in 1978. And already in 1999 the automatic interplanetary probe "Stardust" was launched to the comet.
Image above: The nucleus of Comet Wild 2 (81P / Wild). Photo of the probe "Stardust", 2004.
In 2004, "Stardust" approached the comet at a distance of 240 km. After that, her detailed photographs were taken and samples of the substance from the coma and tail were collected, which were returned to Earth in the landing capsule. It turned out that the dimensions of the comet's nucleus are 5.5 × 4 × 3.3 km, with an average density of 0.6 g / cm3, since the bulk of the comet's nucleus is a conglomerate of ice blocks of water, nitrogen, carbon dioxide and carbon monoxide with many voids cemented with silicate stone substance.
Stardust probe
The main thing that surprised the scientists after processing the data obtained was the predominance of olivine (Mg, Fe) 2 [SiO4] in the cometary rocks. According to the conditions of formation on Earth, olivine belongs to deep-seated high-temperature minerals with a melting point of 1400–1600° C. No less surprising was the presence in the rocks of the comet of crystals of osbornite (titanium nitride with the formula TiN) - a very rare mineral found first in meteorites and much later on Earth. The crystallization temperature of this mineral is 1700° C.
Orbit of Comet Wild 2 (81P / Wild)
Thus, the data obtained by the Stardust mission make it possible to assert that comets contain matter formed at a wide variety of temperatures and throughout the entire space of the solar system, and the source material of comets, apparently, was formed both before and after the formation of the solar system.
Source: Moscow Planetarium.
Related links:
ROSCOSMOS Press Release: https://www.roscosmos.ru/31531/
Moscow Planetarium: https://www.roscosmos.ru/tag/moskovskiy-planetariy/
For more information about Stardust mission, visit: https://www.jpl.nasa.gov/missions/stardust
Images, Text, Credits: ROSCOSMOS/Moscow Planetarium/NASA/Orbiter.ch Aerospace/Roland Berga.
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