Two organic compounds essential for life have been found in samples taken from the asteroid Ryugu, reinforcing the idea that some of the key ingredients for the birth of life have reached Earth on Earth. rocks from space billions of years ago.
On Tuesday, scientists said they had detected uracil and niacin in rocks that the Japan Space Agency’s Hayabusa2 spacecraft collected from two locations on Ryugu Island in 2019. Uracil was one of the few. The chemical building block for RNA, a molecule that guides the construction and operation of living organisms. Niacin, also known as Vitamin B3 or nicotinic acid, is essential for their metabolism.
The Ryugu samples, which look like dark gray rubble, have been shipped 155 million miles (250 million km) back Earth and returned to the surface of our planet in a sealed capsule that landed in 2020 in the remote Australian outback for analysis in Japan.
Scientists have long pondered over the conditions needed for life to form after Earth formed about 4.5 billion years ago. The new findings are very consistent with the hypothesis that organisms such as comet, small planet And meteorite bombarded the early Earth that seeded the young planet with compounds that helped pave the way for the first microbes.
Scientists have previously detected important organic molecules in carbon-rich meteorites found on Earth. But there is a question as to whether these space rocks were contaminated by exposure to the Earth’s environment after landing.
“Our key finding is that uracil and niacin, both biologically significant, are indeed present in extraterrestrial environments, and they may have been supplied to the early Earth as a component of asteroids and meteorites. We suspect that they played a role in pre-evolutionary biology on Earth and possibly the appearance of the first life,” said astrophysicist Yasuhiro Oba of Hokkaido University. in Japan, said lead author of the study published in the journal Nature Communications.
“These molecules on Ryugu were recovered in a pristine extraterrestrial environment,” says Oba. “It was sampled directly on asteroid Ryugu and returned to Earth, and ultimately to laboratories, without any exposure to terrestrial contaminants.”
RNA, which stands for ribonucleic acid, would not be possible without uracil. RNA, a molecule found in all living cells, is important in the encoding, regulation and functioning of genes. RNA is structurally similar to DNA, a molecule that carries the genetic blueprint of an organism.
Niacin is important in boosting metabolism and can help create the “energy” that powers living organisms.
The researchers extracted uracil, niacin, and several other organic compounds in the Ryugu samples by immersing the material in hot water, then performing analyzes called liquid chromatography and mass spectrometry. high resolution.
Organic astrophysicist and study co-author Yoshinori Takano of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) said he is now looking forward to the results of the analysis of the returned samples to Earth. in September from another asteroid. The US space agency NASA on the OSIRIS-REx mission collected samples in 2020 from the asteroid Bennu.
Oba said uracil and niacin were found at both landing sites on Ryugu, which are about half a mile (900 meters) in diameter and are classified as near-Earth asteroids. Concentrations of compounds were higher at one of the sites than at the other.
Samples from the lower concentration site, taken from surface material, are more susceptible to decay due to energetic particles launched in space, Oba said. The sample from the other site was mainly taken from subsurface material that is better protected from degradation, Oba added.
Asteroids are primordial rocky objects that formed in the early solar system. The researchers suggest that the organic compounds found on Ryugu may have formed with the help of chemical reactions caused by starlight in icy materials located in interstellar space. Why.
© Thomson Reuters 2023
