Mineral samples collected from asteroid Ryugu continue to be a treasure trove of interesting information for scientists, with a new analysis revealing the object’s birthplace.
It turns out that Ryugu originated towards the outer regions of the Solar System, where comets usually form.
A large team of researchers led by a team from Hokkaido University in Japan took a close look at the minerals that make up Ryugu, using instruments such as a scanning electron microscope and a secondary ion mass spectrometer.
Specifically, they looked at the levels of oxygen 16 isotopes.
“The oxygen isotopic compositions of primary minerals can potentially provide important constraints on their origin,” planetary scientist Noriyuki Kawasaki and colleagues from Hokkaido University write in their published paper.
Comets form farther from the Sun than asteroids, and because of the colder temperatures in these distant regions, they retain a significant amount of ice as part of their composition. Asteroids, by comparison, are made almost entirely of rock.
The presence of carbonate minerals in the Ryugu dust samples, along with amino acids, suggests that the asteroid formed in low-temperature, watery conditions – so somewhere out there where ice doesn’t evaporate easily, perhaps in the regions around Uranus and Neptune.
That’s not all though: the team also managed to identify minerals such as spinel, olivine and perovskite that form at higher temperatures (above 1,000 degrees Celsius or 1,832 degrees Fahrenheit).
The hypothesis is that some material from the inner Solar System traveled outward away from the Sun, eventually colliding with Ryugu and becoming part of it.
Ryugu’s copper and zinc isotopes closely match those of the carbonaceous meteorite Ivuna discovered many years ago in Tanzania, the researchers report. There are also similarities in the composition of comet 81p/Wild 2, meaning it likely formed the same way, in a haze of material from the inner and outer Solar System.
All this detective work is helping scientists map out Ryugu’s geological history and its place in the Universe. The asteroid is likely to be billions of years old and carries with it clues to the early years of the Solar System.
Until this point, meteorites like Ivuna, known as carbonaceous chondrites, have been used by scientists to make educated guesses about the asteroids and comets that have hit Earth throughout its history. But now, we have samples taken from the vacuum of space to study.
Scientists have already determined that Ryugu contains particles from other stars that exploded before the Sun formed. The asteroid is likely to tell us much more in the future as studies of the material collected from it continue.
“We conclude that Ryugu’s accretion area [and Ivuna-type] The parent bodies are different from those for other groups of carbonaceous chondrites, including Lake Tagish, and could be closer to the accretion region of comet 81P/Wild2,” the researchers conclude.
The research has been published in Advances in Science.