More than 20 types of amino acids have been detected in samples from the Japanese space probe Hayabusa 2 that brought it to Earth from an asteroid in late 2020, a government official said on Monday, showing for the first time the organic compounds found on asteroids in space.
With the amino acids necessary for all living things to make proteins, the discovery could hold clues to understanding the origins of life, the Department of Education said.
In December 2020, the capsule carried by Hayabusa 2 on a six-year mission transported more than 5.4 grams of surface material to Earth from the asteroid Ryugu, located more than 300 million km away.
File picture of the asteroid Ryugu captured by Hayabusa 2 in November 2019 (Photo courtesy of JAXA) (Kyodo)
The Ryugu probe aims to unravel the mysteries of the origin of the solar system and life. Previous analysis of the samples indicated the presence of water and organic matter.
The full investigation of the sample was launched in 2021 by the Japan Aerospace Exploration Agency and research institutions nationwide including the University of Tokyo and Hiroshima University.
Although it is not known how the amino acids got to ancient Earth, one theory is that they came by meteorites, with the amino acids discovered in a meteorite found on Earth. But there is also a possibility that they are fixed to the ground.
Meteorites that reach Earth burn up when they hit the atmosphere, and quickly become contaminated with terrestrial microorganisms.
Hayabusa2 was a pioneer in collecting subterranean materials that were unaffected by sunlight or cosmic rays, and transporting them to Earth without exposure to outside air.
Kensei Kobayashi, professor emeritus of astrobiology at Yokohama National University, said the unprecedented discovery of multiple types of amino acids on an extraterrestrial body could indicate the existence of extraterrestrial life.
A capsule used to send asteroid samples back to Earth from the Japan Aerospace Exploration Agency’s Hayabusa2 space probe is shown to the public at Sagamihara City Museum, Kanagawa Prefecture, March 12, 2021 (Kyodo)
He said, “Proving the presence of amino acids in the interior of the Earth from asteroids increases the possibility of compounds arriving at Earth from space.”
This also means that amino acids can likely be found on other planets and natural satellites, Kobayashi added, indicating that “life could have been born in more places in the universe than previously thought.”
Hayabusa2 left Earth in 2014 and reached its fixed position above Ryugu in June 2018 after traveling 3.2 billion kilometers in an elliptical orbit around the sun for more than three years.
The probe landed on the asteroid twice the following year, and collected the first-ever subsurface samples from an asteroid.
JAXA announces a “big discovery” about asteroids next spring
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