Scientists have confirmed that organic molecules are found in samples taken from the asteroid Ryugu, lending credence to the idea that the ingredients for life arrived on Earth via meteorite and asteroid strikes.
Ryugu is a primitive carbonaceous asteroid, a rocky remnant from the formation of the Solar System over 4 billion years ago. Japan’s Hayabusa2 mission visited Ryugu and collected samples from its surface in 2019, giving us a great way to learn what the solar system was like in its early stages.
A team of researchers has now identified hundreds of thousands of ion signals from the Ryugu samples, which they attribute to a range of organic molecules, including 15 amino acids, amines, aromatic hydrocarbons and other compounds. Their research is published in science.
“The presence of prebiotic molecules on the asteroid surface despite the harsh environment caused by solar heat and ultraviolet irradiation, as well as cosmic ray irradiation under high vacuum conditions, suggests that the uppermost surface grains of Ryugu have the potential to protect organic molecules,” said Hiroshi Naraoka, a planetary scientist at Kyushu University in Japan and the paper’s lead author, in a NASA Goddard Space Flight Center release.
“These molecules can be transported throughout the solar system, potentially dispersing as interplanetary dust particles after being ejected from the upper layer of the asteroid by impact or other causes,” Naraoka added.
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A lingering question in biochemistry is how the building blocks of life, such as amino acids, came to Earth. Organic molecules such as amino acids and nucleotides have been found before in meteorites that fell to Earth, but they are inevitably contaminated by the terrestrial environments in which they land.
That makes the Ryugu find special. The Japan Aerospace Exploration Agency (JAXA). Hayabusa2 snapped clumps of dust, pebbles and gas from the Ryugu asteroid in 2019, when it was nearly 200 million miles from Earth. The mission brought back about 5.4 grams of asteroid samples (about a teaspoon worth) to the earth in 2020.
The research team noted that the Ryugu samples were exposed to space and the conditions that come with it, from micrometeoroid impacts to heating from the sun. “The presence of prebiotic molecules on the asteroid surface suggests that these molecules can be transported throughout the solar system,” the team wrote in their new paper.
NASA’s OSIRIS-REx mission is currently on its way back from the asteroid Bennu, where it conducted a similar sampling operation.
“We will make a direct comparison of the samples from Ryugu and the sample from asteroid Bennu when NASA’s OSIRIS-REx mission returns it to Earth in 2023,” study co-author Jason Dworkin, an astrochemist at NASA’s Goddard Space Flight Center, said in the release.
“OSIRIS-REx is expected to return much more sample mass from Bennu and will provide another important opportunity to look for traces of organic building blocks of life in a carbon-rich asteroid,” Dworkin added.
Comparing the chemical composition of the two asteroids will reveal similarities and differences between the two rocks and help scientists fill in the gaps in our understanding of the ht formation of the Solar System.