Microscopic inclusions of very unusual chemical and isotopic composition have been observed in grains of sand delivered from the asteroid Ryugu. Scientists considered them to be the remnants of a substance that preceded the solar system and was preserved on the asteroid as in a "time capsule".
Asteroids are almost the same age as the solar system. Unlike planets, they have changed little in the billions of years since then, preserving samples of the ancient matter from which our system formed. Until recently, however, scientists could only examine samples that had fallen to Earth and been visibly transformed in the process of such a catastrophe. But the material that spacecraft manage to collect and deliver remains just as pristine, allowing astronomers a glimpse into an era when the solar system was just forming.
In the 2018-2019s, Japan's Hayabusa2 space probe collected samples of matter from near-Earth asteroid (162173) Ryugu and dropped a capsule containing them back to Earth in 2020. At the disposal of scientists got a few grams of unique material, which they are still analyzing with great care, trying not to allow the slightest contamination. Among other things in its composition found organic compounds and water - important evidence of the past of our world, if not even older.
New work by American and Japanese scientists has shown that the composition of samples from Ryugu contains a substance older than the solar system. The article is published in the journal Science Advances.
Ann Nguyen (Ann Nguyen) and her colleagues analyzed a pair of "grains of sand" asteroid, each less than a millimeter across. The scientists noticed even tinier inclusions prominently displayed on the surface. Having examined them with the help of electron microscopes, X-ray spectroscopy and other methods, the authors of the study found that the composition of these parts is markedly different from the main substance of the asteroid.
It contains less oxygen, magnesium, silicon, but more iron and sulfur, as well as simple organic substances. In addition, silicon carbide (SiC) is present, a compound that easily disintegrates on contact with water. All this shows that such inclusions were formed separately from the main substance of Ryugu and did not interact with water. This was confirmed by isotopic analysis.
Scientists believe that these particles vaporized from the surface of comets, on the far periphery of the solar system, and only later were captured by Ryugu, more precisely - the parent asteroid, of which it is a fragment. This occurred before the formation of the planets and even before the differentiation of the matter from which they formed. The tiny inclusions in Ryugu have preserved material that originated in previous stars whose remains served as building material for ours. Perhaps they will give us a better idea of what the "progenitors" of the Sun and its planets were like.