The team is identifying materials from the parent body of the Ryugu asteroid

An international team, including a researcher from Lawrence Livermore National Laboratory (LLNL), has found that a specific particle on asteroid Ryugu may shed light on the unmodified parent materials of its parent body.

In December 2014, the Japanese Aerospace Exploration Agency launched the Hayabusa2 spacecraft to asteroid 162173 Ryugu. In December 2020, the sample return pod containing pristine Ryugu pieces it had collected successfully landed safely on Earth.

Ryugu is an ancient fragment of a larger asteroid that formed very early in the solar system’s history, shortly after the birth of the sun. Samples from this asteroid offer a unique opportunity to determine not only the material from which the solar system formed, but also how the solar system evolved.

The solar system formed from a large cloud of swirling gas and dust formed by previous generations of stars. This “stardust” consists of nanometer to micrometer sized particles that are incorporated into planetary bodies like Ryugu as they form.

In the new research, LLNL secondary ion mass spectrometrist and cosmochemist Ming-Chang Liu (Nuclear and Chemical Sciences Division) found that one particle (designated C0009) is mineralogically distinct from other Ryugu particles because it contains a small amount ( ~0.5% by volume) contains anhydrous silicates. Other particles examined to date contained more phyllosilicate and carbonate minerals, suggesting that Ryugu underwent extensive aqueous alteration on its parent body, similar to the rare mineralogically altered but chemically primitive CI chondrites (a group of rare stony meteorites). The research appears in natural astronomy.

Through isotopic analysis of magnesium-rich olivine and pyroxene, the data provide “strong evidence that amoeboid olivine aggregates and magnesium-rich chondrules, two types of high-temperature objects that formed in the solar nebula, were accreted in Ryugu’s mother body,” said Liu, who served as the paper’s first author acts.

The team analyzed the results of oxygen isotope measurements of Ryugu’s anhydrous silicates, which have strong implications for the origins of Ryugu and thus the parent asteroids of CI chondrite meteorites.

“The oxygen isotope data together with the grain morphology allow us to infer the original materials incorporated into the Ryugu protoliths as they reveal a potential relationship between anhydrous silicates in C0009 and other known high-temperature components found in carbonaceous non-CI chondrites can be found,” Liu said.