Fragments of a comet detected inside a meteorite that fell to Earth

American scientists have discovered traces of primary rocks from which the planets of the solar system were formed in a very unexpected place – inside one of the meteorites that fell on the south pole of the Earth in the recent past. While analyzing the findings, the researchers placed a cut of a meteorite under a microscope and found inside it miniature dark inclusions (0.1 mm in size) of an incomprehensible nature, containing a record large amount of organic and volatile substances, including ketones and sugars. It turned out that inside the cosmic stone there is a comet embryo. Researchers report their unique discovery in an article published by the journal Nature Astronomy.

According to the research group, under the leadership of Larry Nittler from the Carnegie Institute of Science in Washington (USA), the asteroid served as a kind of protective capsule, inside which the “embryos” of comets and grains of primary matter of the Solar System remained. She helped them survive the journey through the atmosphere of the Earth. Scientists are very pleased with this discovery, because now they have samples of matter that would never get here by themselves.

To make it clearer why the find is unique, let’s clarify a couple of points. Meteorites are small celestial bodies that have already fallen on the surface of the Earth. Previously, they could be part of asteroids — other larger solid celestial bodies wandering around our Solar System since its formation and as a result, not becoming part of the planets or comets — they resemble asteroids but contain volatile chemical elements that are exposed to sunlight evaporates from the surface of a celestial body, creating a so-called “coma” – the tail. These objects never fall to Earth (fortunately). But scientists are very interested in what they consist of.

Conducting an isotopic analysis of the composition of the LAP 02342 meteorite sample found in Antarctica, scientists found atypical fractions of heavy oxygen, deuterium and nitrogen-15, which do not coincide with other small bodies of the Solar System, or with the Sun, or with the planets. As the researchers note, scientists did not find anything like this in meteorites, however they encountered similar composition of matter, exploring other celestial bodies directly in space. In particular, scientists note the comet Churyumov-Gerasimenko, as well as samples of matter that have fallen into the solar system from the interstellar medium. A similar composition, as suggested by planetologists, had a protoplanetary nebula, where the Sun, the Earth and all other planets were born.
 

According to Nature Astronomy’s authors, this dust could have gotten into an asteroid in the distant past, approximately 3 million years after the birth of our Sun. During this period, cosmic dust began to coalesce and form larger stones, which later became the nuclei of comets and asteroids. Periodically, these objects collided with each other, which sometimes led to their “merging”, and in other cases – to mutual destruction. Nittler and the team say that traces of one of the most ancient collisions of this kind, which occurred about 4.4 billion years ago, were found precisely in samples of the meteorite LAP 02342.

Recall that currently several world space agencies are conducting space missions aimed at collecting samples of the ancient matter of the solar system. For example, using the OSIRIS-REx spacecraft, the NASA aerospace agency is trying to get samples of the dust from the Bennu asteroid. And the Japanese spacecraft Hayabusa-2 is currently collecting ground samples of the asteroid Ryugu. In both cases, the obtained samples are planned to be delivered back to Earth for analysis, but the finding of scientists from the Carnegie Institute of Science in Washington allows you to do this today, without waiting for the return of the American and Japanese missions.