First results from space

Max Planck researchers from Göttingen examine rocks from the asteroid Ryugu. Important insights have already been gained from valuable samples.

Göttingen – In Göttingen, rock grains from the asteroid Ryugu are examined and analyzed at the Max Planck Institute for Solar System Research (MPS). The valuable sample retrieved from space is priceless, and was opened, defrosted and analyzed at MPS in July.

Its purpose is to provide clues about the origin of our solar system, and the initial results have been groundbreaking.

The asteroid had a shorter journey after all

The asteroid Ryugu, about 900 meters in diameter, may not have traveled as far from its place of formation to its current near-Earth orbit as previously thought. This is what new studies published in the journal Science Advances have shown. More precisely: Ryugu could have originated near Jupiter. Previous studies have determined its origin outside Saturn's orbit.

The Japanese space probe Hayabusa 2 brought samples from Ryugu to Earth four years ago. Researchers led by the MPS in Göttingen have now compared the types of nickel found in it and in typical carbon-rich meteorites.

An alternative to previous ideas

As I said, the results show an alternative to previous ideas about the birthplaces of these bodies. Accordingly, it is possible that different carbon-rich asteroids formed in the same region near Jupiter – albeit partly through different processes and about two million years apart.

“The results really surprised us. We had to completely rethink – not only regarding Ryugu, but also regarding the entire set of CI chondrites,” says Dr. Christoph Burckhardt of MPS.

Strange relatives

CI chondrites now appear no longer as distant, exotic relatives of the remaining carbonaceous chondrites from the outer edge of the solar system, but as younger siblings that may have formed in the same region but later and through a different process.

According to the Director of the Planetary Sciences Department at the Max Planck Institute for Solar System Research, Professor Thorsten Klein, the current study shows “how important laboratory studies are that can contribute to deciphering the history of the formation of our solar system.”

Three and a half years until the start of the trial

It took three and a half years until the rehearsal opened in Göttingen in mid-July. In order to obtain it, “MPS submitted a standard request,” laboratory director Timo Hoppe told our newspaper.

The contract was also awarded because the know-how was available in Göttingen – and the technology was installed in containers on the roof of the MPS building. It includes: clean rooms, and special laboratories made entirely of plastic, because every metal molecule would falsify the analysis. The sample was thawed and prepared there and then examined with a mass spectrometer located in the basement of the building. It has been completely ionized.

The rocks in Göttingen weigh only a few grams

Rock samples from the asteroid Ryugu, which weigh only a few grams and were brought to Earth by the Japanese space probe Hayabusa 2 in December 2020, have been through a lot. After initial studies in Japan, some of the small black beads moved to research facilities around the world. There they were measured, weighed, chemically analyzed, and exposed to simultaneous infrared, X-ray, and acoustic radiation.

In MPS, researchers, as in the current study, examine the presence of certain metal isotopes in samples. Scientists refer to variants of the same element that differ only in the number of neutrons in the nucleus as isotopes. Studies of this kind could help understand where Ryugu formed in the solar system.

Near-Earth asteroid

Ryugu is one of the near-Earth asteroids: its orbit around the Sun intersects Earth's orbit without any risk of collision. However, researchers assume that it, like other near-Earth asteroids, “traveled” to the inner solar system from the asteroid belt between the orbits of Mars and Jupiter. The actual birthplaces of the inhabitants of the asteroid belt are likely to be far from the Sun, outside the orbit of Jupiter.

The MPS team studied the nickel isotope ratios for the first time in four samples from the asteroid Ryugu and six samples from carbonaceous chondrites. This confirmed the close relationship between Ryugu and CI chondrites. But the idea of ​​a common birthplace at the edge of the solar system is no longer convincing.

The allure of the young sun

According to the researchers, the first carbonaceous chondrites began to form about two million years after the formation of the solar system. Because of the gravity of the still-young Sun, the first dust and solid masses made their way from the outer edge of the gas and dust disk into the inner solar system, but they ran into an obstacle: the newly formed planet Jupiter.