Asteroid Samples Brought to Earth Contain Key Molecules for Life

A canister containing a sample from Ryugu, given to NASA by Japanese space agency JAXA.

A canister containing a sample from Ryugu, given to NASA by Japanese space agency JAXA.
Photo: NASA/Robert Markowitz

Japan’s education ministry says that more than 20 types of amino acids were detected in samples of an asteroid that were brought to Earth in December 2020, The Japan Times reports. The detection is the first evidence that amino acids exist on asteroids in space and has implications for understanding how such vital organic molecules arrived on Earth.

The Hayabusa2 spacecraft collected the samples from an asteroid named Ryugu. The Japan Aerospace Exploration Agency (JAXA) probe landed on Ryugu—nearly 200 million miles from Earth—in 2019and it collected about 5.4 grams of samples from the asteroid’s surface and subsurface.

Ryugu is a carbon-rich fragment of a larger asteroid that formed from the same gas and dust that gave way to our solar system. Because of their age, dust and rocks from Ryugu’s surface offer scientists a look at what material was floating around in the early solar system over 4 billion years ago.

At the Lunar and Planetary Science Conference held in Texas in March, Hisayoshi Yurimoto, a geoscientist at Hokkaido University in Japan and a member of the Hayabusa2 team, described the distant asteroid as “the most primitive material in the solar system we have ever studied,” according to

Today’s news reveals the sizable number of amino acids on the distant space rock, which members of the Hayabusa2 team believe could spread through the solar system in the form of interplanetary dust.

The asteroid Ryugu.

Amino acids are the building blocks of proteins, making them essential organic molecules for life. Ancient rocks on Earth have offered evidence that similar molecules to those found on Ryugu arrived here billions of years ago.

“Our final objective is to understand how organic compounds formed in the extraterrestrial environment,” said Hiroshi Naraoka, a geochemist at Kyushu University in Japan, and a member of the Hayabusa2 team, in a 2020 NASA release. “So we want to analyze many organic compounds, including amino acids, sulfur compounds, and nitrogen compounds, to build a story of the types of organic synthesis that happens in asteroids.”

It’s possible that such essential organic molecules first arrived on Earth through impacts from comets and asteroids, and the Ryugu samples have now proven that these molecules exist on asteroids in space. That’s important, because asteroid and cometary impacts on Earth are almost immediately contaminated with terrestrial matter, which can make it difficult for scientists to separate what was always on the rock from what newly tainted it.

As more data from Ryugu samples are analyzed, we’ll get more information about the asteroid’s composition and how it formed. By comparing results from the Ryugu material to the samples collected from Bennuan asteroid visited by NASA in 2020, we’ll get a better understanding of the various chemical cocktails in the cosmos, and perhaps how life arose from it all.

More: Asteroid Sample Brought to Earth Exposes Ryugu’s Hidden Interior


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