A meteorite that landed in the Sahara Desert last year is older than Earth. More interestingly, its age and mineral content suggest that it once formed part of the crust of a forming planet.
The pinned meteorite EC 002 was discovered in May 2020 in the Erg Chech sand sea, Algeria. The rock quickly stood out. Rather than the chondritic composition of most recovered meteorites (chunks of dust and rock that stick together), its texture was indeed igneous, displaying inclusions of pyroxene crystals.
The rock was therefore quickly classified as an achondrite. It is a type of meteorite composed of volcanic material from a parent body with a distinct crust and core. There are about 3100 of these objects on Earth, but most originate from rocky asteroids. And of that sample, about 95% comes from just two parent bodies, one of which is the asteroid Vesta, one of the largest objects in the asteroid belt. EC 002 stands out.
Recent analyzes of the aluminum and magnesium isotopes contained within indicated that its parent body was very ancient, 4.566 billion years old. years .
Its chemical composition also revealed that it was "forged" in a reservoir of partially melted magma in the crust of the parent's body. Most rocky meteorites come from sources with basaltic crusts – rapidly cooled lava that is rich in iron and magnesium – but the composition of EC 002 suggests that its parent body's crust was made of andesite, a material rich in in silica.
However, studies have already shown that such silica-infused andesite crusts were probably common during the formation phase of forming planets (protoplanets).
Furthermore, after comparing the "fingerprints" of EC 002 with those of all known asteroid groups (analysis of wavelength patterns in the light that they emit or reflect), the researchers found no matches.
Also they conclude that this meteorite is probably the piece of a protoplanet that has since been destroyed or absorbed by larger rocky planets when our system formed. At the time, the environment of our Sun was indeed chaotic. Too chaotic for many planetary embryos.
You will find the details of the study in the journal Proceedings of the National Academy of Sciences .
