Japan's Hayabusa 2 asteroid sample sheds new light on the early solar system

"Ryugu is a very pristine asteroid that represents the beginnings of our solar system".
Chris Young
An artist's illustration of the Hayabusa2 spacecraft.
An artist's illustration of the Hayabusa2 spacecraft.

Source: Wikimedia Commons 

In December 2020, Japanese space agency JAXA's Hayabusa 2 mission returned samples from asteroid Ryugu to Earth.

The Hayabusa 2 spacecraft dropped a capsule containing the samples — materials dating back to the beginnings of our solar system — into Earth's atmosphere before continuing its journey to another asteroid.

The 5.4 grams (0.2 ounces) of rocks and dust collected from the asteroid Ryugu are helping the global scientific community better understand our solar system's early formation.

As per a press statement, some of the first researchers to study those samples discovered accumulations of rare earth elements as well as a surprising structure. They reported their findings in the journal Science.

Hayabusa 2 mission sheds light on early solar system

Geoscientist Professor Frank Brenker and a team from Goethe University Frankfurt were some of the first scientists to study the samples. They used a state-of-the-art proprietary analysis method to investigate the chemical composition of the samples without damaging any of the materials.

Their method, called "Synchrotron Radiation-induced X-Ray Fluorescence Computed Tomography", or SR-XRF-CT, allowed them to analyze the materials with a resolution of under 100 nanometers.

JAXA chose the Ryugu asteroid as a target because its high carbon content promised to reveal a great deal about the origin of life in our solar system. The new analysis confirms that the asteroid was originally part of a parent asteroid formed in the outer solar nebula.

Ryugu: "a very pristine asteroid"

The researchers found an accumulation of magnetite, an iron oxide mineral, as well as hydroxyapatite, a phosphate mineral, in one of the grains of the asteroid. These were formed in a fine vein-like structure. Other scientists found that these must have formed at a surprisingly low temperature of less than 40 °C. Knowing this will prove vital for future analysis of the samples.

In the parts of the samples containing hydroxyapatite, the scientists also discovered the presence of rare earth metals.

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“The rare earths occur in the hydroxyapatite of the asteroid in concentrations 100 times higher than elsewhere in the solar system,” Brenker explained, adding that the rare earth metals accumulated in the phosphate mineral in equal amounts. “This equal distribution of rare earths is a further indication that Ryugu is a very pristine asteroid that represents the beginnings of our solar system," he continued.

JAXA raised approximately $120 million for its Hayabusa 2 mission, which is now making its way to a smaller asteroid and is expected to arrive by 2031. Earlier this year, another study of the Ryugu samples showed that much of the early Earth's water might have come from asteroids.

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