A tiny piece of the comet primary building block is found inside a primitive meteorite. The discovery provides new keys to the formation, structure and evolution of the solar system.
Meteorites were once part of larger asteroids, which disintegrated due to collisions in space and survived a journey through the Earth’s atmosphere. Their composition may vary significantly, reflecting their origin from different parts of the solar system.
The meteorite was named LaPaz Icefield 02342 by the name of the place where it was found – on the LaPaz ice field in Antarctica. It belongs to a class of primitive carbonaceous chondrites that underwent minimal changes because they were formed over 4.5 billion years ago, probably outside the orbit of Jupiter.
-Jemma Davidson, a researcher at the University of Arizona (USA)
Asteroids and comets originated in the gas-dust disk that once surrounded the young Sun, but they formed at different distances from it, which affected their chemical composition. Compared to asteroids, comets contain larger fractions of water ice and much more carbon and usually come from areas farther from the Sun where the environment was colder.
Studying the chemistry and mineralogy of a meteorite, the researchers reveal the details of its formation and how much heat and other chemical processing it has experienced during the years of the formation of the solar system.
Surprise inside
Inside the LaPaz meteorite, the team found a very carbon-rich piece of primitive material. It bears a striking resemblance to particles of extraterrestrial dust, which are believed to have originated in comets formed near the outer edges of the solar system. Approximately 3–3.5 million years after the birth of the Solar System, this tiny object — about 0.1 millimeter across — was captured by a growing asteroid, from which a meteorite arose.
Primitive meteorites store the prints of the early Solar system, which we can study in the laboratory. Meteorites like LaPaz are great places to search for microscopic pieces of star dust made up of stars preceding the solar system.
-Gemma Davidson
But none of the team also expected to find evidence of the survival of the cometary building block inside the meteorite.
Ancient survivor
Having conducted a complex chemical and isotopic analysis of the material, scientists have shown that it probably originated from the icy outer solar system, along with the Kuiper belt objects, from which many comets originate.
Since this sample of the cometary building block was“ swallowed ”by an asteroid and stored inside a meteorite, it was protected from the destructive effects of the Earth’s atmosphere. This gave us the opportunity to look at the material that could not independently reach the surface of our planet and understand the chemistry of the early solar system.
-Larry Nittler, lead author of the Carnegie Research Institute (USA)
The primitive material captured by a meteorite suggests that particles like it migrated from the outer edges of the solar system towards Jupiter, where carbonaceous chondrites were formed. This reveals the details of how the architecture of the solar system was formed in the early stages of the origin of the planets.
Such discoveries demonstrate how important it is to extract precious meteorites, such as LaPaz. You cannot know in advance what secrets they will reveal.
-Gemma Davidson
Solar system primary building block is found in a meteorite
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