Asteroid discovery suggests ingredients for life on Earth came from outer space
Two organic compounds essential to living organisms have been found in samples recovered from the asteroid Ryugu, bolstering the idea that some crucial ingredients for the advent of life arrived on Earth aboard rocks from space a while ago. billions of years.
Scientists said Tuesday they detected uracil and niacin in rocks obtained by the Japanese Space Agency’s Hayabusa2 spacecraft from two sites on Ryugu in 2019. Uracil is one of the chemical elements base of RNA, a molecule that carries instructions for building and operating living organisms. Niacin, also called vitamin B3 or nicotinic acid, is vital for their metabolism.
The Ryugu samples, which looked like dark gray rubble, were transported 250 million kilometers (155 million miles) to Earth and returned to our planet’s surface in a sealed capsule that landed in 2020 in the rear -Australian country for analysis in Japan.
Scientists have long thought about the conditions necessary for the appearance of life after the formation of the Earth about 4.5 billion years ago. The new findings fit well with the hypothesis that bodies like comets, asteroids and meteorites that bombarded early Earth seeded the young planet with compounds that paved the way for the first microbes.
Scientists have previously detected key organic molecules in carbon-rich meteorites found on Earth. But there was the question of whether these space rocks had been contaminated by exposure to Earth’s environment after landing.
“Our key finding is that uracil and niacin, both of which are biologically important, do indeed occur in extraterrestrial environments and may have been supplied to early Earth as components of asteroids and meteorites. We suspect that they played a role in prebiotic evolution on Earth and possibly for the emergence of first life,” astrochemist Yasuhiro Oba of Hokkaido University told Reuters. Japan, lead author of the research published in the journal Nature Communications.
“These molecules on Ryugu were recovered from a pristine alien setting,” Oba said. “It was taken directly from the asteroid Ryugu and returned to Earth, and finally to laboratories without any contact with terrestrial contaminants.”
RNA, short for ribonucleic acid, would not be possible without uracil. RNA, a molecule present in all living cells, is vital in the coding, regulation and activity of genes. RNA has structural similarities to DNA, a molecule that carries an organism’s genetic fingerprint.
Niacin is important for supporting metabolism and can help produce the “energy” that powers living organisms.
The researchers extracted uracil, niacin and some other organic compounds from the Ryugu samples by soaking the material in hot water and then performing analyzes called liquid chromatography and high-resolution mass spectrometry.
Organic astrochemist and study co-author Yoshinori Takano of the Japan Agency for Marine and Earth Science and Technology (JAMSTEC) said he is now eagerly awaiting the results of analyzes on the samples returned to Earth in September by another asteroid. The American space agency NASA during its OSIRIS-REx mission collected samples from the asteroid Bennu in 2020.
Oba said uracil and niacin were found at the two landing sites in Ryugu, which measures around 900 meters in diameter and is classified as a near-Earth asteroid. Concentrations of compounds were higher at one site than at the other.
The site sample with the lowest concentrations was derived from surface material more susceptible to degradation induced by energetic particles traveling through space, Oba said. The sample from the other site came mostly from underground material that was more protected from degradation, Oba added.
Asteroids are rocky primordial bodies that formed at the beginning of the solar system. The researchers suggest that the organic compounds found on Ryugu may have been formed using chemical reactions caused by starlight in icy materials residing in interstellar space.
© Thomson Reuters 2023
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