Photo/Illutration Scientists at Hokkaido University select a sample from the Ryugu asteroid for further analysis. (Provided by Hisayoshi Yurimoto of Hokkaido University)

The sample brought back to Earth by the Hayabusa 2 space probe is described as being very “fresh” because it originated relatively soon after the birth of the solar system about 4.6 billion years ago. 

International teams of researchers are examining the sample retrieved from the asteroid Ryugu and dropped to Earth in December 2020 in a capsule. On June 10, the first two articles about some of the findings appeared in two scientific journals.

One article published by a joint team of researchers from Hokkaido University and the Japan Aerospace Exploration Agency in the Science journal concluded that the minerals found in the sand sample were created about 5 million years after the solar system was formed.

“The Hayabusa 2 brought back extremely ‘fresh’ samples,” said Shogo Tachibana, a professor of earth and planetary science at the University of Tokyo who was a member of the research team, at a June 9 news conference. “I am looking forward to new developments in the future study of the solar system.”

Considering the immense age of the solar system, anything created 5 million years after its birth can be described as coming immediately after its formation.

Scientists believe Ryugu was created through the accumulation of various fragments of other celestial bodies. The original celestial body included ice, which likely melted as the temperature rose.

Minerals were formed through chemical reactions within the water, scientists theorize.

After Ryugu was formed, temperatures on the asteroid do not appear to have ever exceeded 100 degrees. The ratio of the chemical elements found in the sand collected on Ryugu is similar to the overall average for the solar system.

Researchers believe this demonstrates that Ryugu maintained the most primitive characteristics of the solar system because it never underwent major change, such as through collisions with other celestial bodies.

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A second team that included researchers from Okayama University published its findings in the Proceedings of the Japan Academy. The team confirmed 23 amino acids in the sample of 0.055 gram of sand. Amino acids are the building blocks of life.

Among the amino acids found were isoleucine, valine and threonine, which human bodies cannot synthesize, as well as glycine, a constituent of collagen, and glutamic acid, an umami flavor component.

The finding is especially important because this is the first time such a wide variety of amino acids was found to be extraterrestrial in origin.

Further research into the amino acids should help scientists determine if those in the Ryugu sample are structurally similar to the large majority of amino acids found in life forms on Earth.

Amino acids are divided into left-handed and right-handed shapes that are mirror images of each other. For some unknown reason, almost all the amino acids found in life forms are of the left-handed variety.

(This article was written by Shiori Ogawa, Ryoma Komiyama and Masanobu Higashiyama.)

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