It could be the most pristine sample of rock we've had so far.
According to a new in-depth analysis of the material delivered to Earth from the asteroid Ryugu, the samples of rocks and dust are among the most uncontaminated Solar System materials we have ever had the chance to study.
This gives us a unique tool for understanding the Solar System and its formation, as well as giving us a new context in which to interpret other space rocks that have come into contact with Earth.
"Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match," said Motoo Ito of the Japan Agency for Marine-Earth Science Technology.
The Sun formed around 4.5 billion years ago. We have time capsule that allow us to study the chemistry of the early Solar System in order to understand how it all came together. These are pieces of rock, such as comets and asteroids, that have not changed since they formed.
It's not easy to collect and return samples from a rock far away. We used to rely on space rocks to get our hands on these time capsule. As the Solar System was still forming, carbonaceous chondrites were the best tool for probing the composition of the asteroids that might have delivered water to Earth.
The record is biased due to a kind of survival of the fittest. Only the strongest pieces of space rock remain after atmospheric entry, and they become contaminated by the environment.
We have been able to touch down on asteroids in the past. The Japanese Space Agency dropped off samples from the surface of the asteroid in December of 2020 after sending a probe to it.
The asteroid is very similar to carbonaceous chondrites, making it a C type asteroid. It may have once been a comet due to the presence of prebiotic molecule.
The new analysis is more detailed. According to Ito and his colleagues, the abundance of heavy hydrogen and nitrogen in the asteroid is consistent with an origin far away from the Sun. The icy bodies are visitors from the Solar System's farther reaches.
The researchers found a glaring difference between the two. ferrihydrite and sulfate are missing from the samples. These compounds were thought to be part of extraterrestrial materials since they are found in meteorites. It's possible that they're the result of weathering in the meteorites.
Future meteorite studies should take into account this possibility and future asteroid sample return missions will be able to shed more light on the matter.
The researchers wrote in their paper that meteorites are contaminated despite their importance as proxies of the bulk Solar System composition.
The importance of direct sampling of primitive asteroids is shown by the findings of this study. The evidence presented here shows that ryugu particles are among the most uncontaminated Solar System materials available for laboratory study and ongoing investigations of these precious samples will definitely expand our understanding of early Solar System processes.
The research was published in a journal.
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