Asteroid Ryugu contains dust older than the solar system

[Still Waters]

Ancient grains of dust that are older than the solar system itself have been found in samples from asteroid Ryugu brought to Earth by the Japanese Hayabusa2 spacecraft nearly two years ago. 

The presence of this pre-solar material in Ryugu is not a surprise, as similar ancient grains were previously found in several carbonaceous chondrite meteorites, which are carbon-rich pieces of space rocks that survived the fall through Earth's atmosphere to land on the planet. 

The ancient particles in samples from Ryugu are made of silicon carbide, a chemical compound that doesn't naturally occur on Earth. According to the researchers behind the new study, there are different kinds of silicon carbide grains that differ by what scientists call their isotopic signatures, or the number of neutrons in the core of the silicon and carbon atoms that make up the compound. 

https://www.space.com/asteroid-ryugu-dust-older-than-solar-system

The study was published in the journal Astrophysical Journal Letters on Monday (Aug. 15).

https://iopscience.iop.org/article/10.3847/2041-8213/ac83bd

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[Eldorado]

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water.

Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment.

Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition.

The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin.

Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.

https://www.nature.com/articles/s41550-022-01745-5

[Still Waters]

Team discovers evidence of cometary dust hitting the asteroid Ryugu

Ryugu is a near-Earth asteroid that gained significant attention when the Japanese Hayabusa2 mission collected samples and returned them to Earth. These samples have proven to offer a treasure trove of insights into the solar system, including the possible role of asteroids in delivering organic molecules to Earth.

Now, a team of scientists has performed an intensive investigation of Ryugu samples, discovering evidence that points to cometary organic matter being transported from space to the near-Earth region.

The team included Megumi Matsumoto, an assistant professor from the Earth Science Department at Tohoku University Graduate School of Science. Details of their findings were published in the journal Science Advances on January 19, 2024.

https://phys.org/news/2024-01-team-evidence-cometary-asteroid-ryugu.html