A small meteorite could reshape our understanding of asteroids

Scientists have launched an analysis of a fragment of a meteorite gathered after an asteroid near the 2008 collision with Earth. These show that the parent asteroid was huge, and the results suggest that a special asteroid, which holds water, may be larger and have different mineral compositions than previously thought.

The results of the study were published this week in Nature Astronomy magazine and look at the chemical composition of a fragment of those meteorite fragments.

The story of the fragments begins in October 2008, when scientists became aware of an asteroid on a course of collision with Earth. They knew that most of the rock would burn at the entrance to the Earth’s atmosphere and that the remains, if any, would fall into the wind-swept sands of the Nubian desert. It provided a unique opportunity for an international team of researchers, including NASA scientists, to anticipate the arrival of rocks and then comb the sands for any surviving fragments.

Although the asteroid was relatively small – only about nine tons – its detritus was tiny; less than 8.8 pounds (4 kilograms) of meteorites were collected from the desert. They were collectively named Almahata Sitta, after a nearby train station. It was the first time an asteroid was observed and then its meteorite remains were collected.

Since the recovery, various pieces of the Almahata Sitta have been analyzed, revealing information about the origins and chemical compositions of different parts of the asteroid. The meteorite sample studied by the teamnicknamed AhS 202 – it was so small that you could fit 10 copies of it on a fingernail, but it came from a Gargantuan space rock, a point of origin that precedes the union of the fragment with the rock mass of Almahata Sitta. The team used infrared light and X-rays to study the sample. They discovered that the fragment was a carbonic chondrite, a type of meteorite that formed in the early days of the solar system and that may have brought water to Earth, giving rise to … all this. In general, it was not believed that carbonic chondrites could come from parent bodies (original asteroids) larger than about 100 kilometers in diameter.

But researchers have discovered tremolite in its bit fragment, a mineral that requires immense pressure to form. The existence of the tremolite in the sample suggests that the diameter of the asteroid of origin is in the range 398 to more than 1,119 miles (640 to more than 1,800 kilometers), putting it in the wheelhouse in Ceres, the biggest object …a dwarf planet, actually“In the asteroid belt.”

“This is proof of a very large parent body that I didn’t know existed before,” said Vicky Hamilton, a scientist at the Southwest Research Institute and lead author of the recent paper, noting the first known presence. of trembling in a carbonic chondrite. “The fact that we have no other evidence in our meteorite collections helps us confirm what we have already suspected, that is, the meteorites we manage to find on Earth are a biased sample.”

As asteroids pass through space, they must come into contact with other bodies. These conglomerations of metals and minerals come together and separate as their trajectory continues. When a meteorite is actually found on Earth, it is a compendium of stories from space and the only way to read it is to do a lot of analysis.

“You can have a group of scientists looking at a piece of a meteorite and another group looking at another piece of the same meteorite and you see two different parts of the history of the solar system,” Hamilton said.

This is how Hamilton’s piece might talk about some origins in a massive asteroid, while another piece of the Almahata Sitta might suggest the existence of a proto-planet. The electroscopy work the team did recently is a kind of reverse engineering, to go from what appears to be a typical space rock to its specific story, in this case being its reference to a massive parent asteroid. It’s like finding a crumb on your kitchen counter – it could be from anywhere – but if you look at it chemically, you can tell yourself the temperature and pressure conditions that gave rise to it and whether the crumb really came from the bread. toasted in the morning or from last week’s birthday cake. .

Although much rarer than other types of asteroids, new information about carbonic chondrites could fall from the sky at any time. It’s just a matter of whether the meteorites are vigilant enough – or lucky enough – to see them.