Meteorite contains data on spitting asteroids

(ORDO NEWS) — In 2019, NASA’s OSIRIS-REx spacecraft sent back an image of an amazing geological phenomenon: the asteroid Bennu was throwing pebbles from its surface into space.

Scientists have never seen such behavior in asteroids before. In a new paper in Nature Astronomy, the researchers report the first evidence of this process.

The Aguas Zarcas meteorite is named after the city in Costa Rica where it fell in 2019. Philip Heck, curator of meteoritics at the Field Museum, and Xin Yang, a graduate student at the University of Chicago, were preparing Aguas-Zarcas for another study when they noticed something unusual.

“We tried to separate tiny minerals from the meteorite by freezing it with liquid nitrogen and thawing it with warm water,” Yang said.

“This method works for most meteorites, but Aguas Zarcas behaved a little strange – we found a few fragments that did not break up.”

Scientists did a CT scan, and found that these meteorite particles are flattened, although they should have been spherical.

The researchers put forward a hypothesis, which was confirmed using physical models. Heck and Young believe that the asteroid was subjected to a high-speed collision, and the impact region was deformed.

This deformed rock eventually collapsed due to the huge temperature differences during the rotation of the asteroid, since the side facing the Sun is more than 145 ° C warmer than the shadow side.

“This constant thermal cycling made the rock brittle and it broke up into gravel,” says Heck. “We don’t yet know what the process is that ejects the pebbles. It can be displaced due to collisions with other space objects.”

Scientists suggest that the pebble entered a very slow orbit around the asteroid, and, in the end, fell back to the part of the surface where there was no deformation.

Then the asteroid underwent another collision, and the pebbles on the surface turned into solid stone. The same blow could dislodge the stone, sending it into space, and so, in the end, the meteorite ended up on Earth.

This theory could explain the presence of pebbles at Aguas-Zarcas, making the meteorite the first physical evidence of a geological process observed by OSIRIS-REx on Bennu.


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