Asteroid suggests ingredients of life came from space – 03/21/2023 – Science

Two organic compounds essential for living organisms were found in samples recovered from the Ryugu asteroid, reinforcing the hypothesis that some crucial ingredients for the advent of life reached Earth aboard rocks from space billions of years ago.

Scientists said on Tuesday they detected uracil and niacin in rocks taken by the Japanese Space Agency’s Hayabusa2 spacecraft from two sites in Ryugu in 2019. Uracil is one of the chemical building blocks of RNA, a molecule that carries instructions to build and operate living organisms. Niacin, also called vitamin B3, or nicotinic acid, is vital to your metabolism.

Ryugu’s samples, which looked like dark gray boulders, were transported 250 million kilometers back to Earth, and returned to our planet’s surface in a sealed capsule that landed in 2020 in Australia’s remote outback for analysis in Japan.

Scientists have long pondered the conditions necessary for life to emerge after Earth formed about 4.5 billion years ago. The new findings fit well with the hypothesis that bodies such as comets, asteroids and meteorites that bombarded the early Earth 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 was also the question of whether or not these space rocks had been contaminated by exposure to Earth’s environment after landing.

“Our main finding is that uracil and niacin, both of biological importance, are actually present in extraterrestrial environments and may have been supplied to early Earth as a component of asteroids and meteorites. We suspect they have a role in prebiotic evolution on Earth. and possibly in the emergence of the first forms of life,” said astrochemist Yasuhiro Oba of Hokkaido University in Japan, lead author of the research published in the journal Nature Communications.

“These molecules in Ryugu were retrieved from a pristine extraterrestrial environment,” said Oba. “It was sampled directly from asteroid Ryugu and returned to Earth and ultimately to laboratories without any contact with terrestrial contaminants.”

RNA, short for ribonucleic acid, would not be possible without uracil. The 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 blueprint.

Niacin is important in sustaining metabolism and can help produce the “energy” that fuels living organisms.

The researchers extracted uracil, niacin and some other organic compounds from Ryugu’s samples by soaking the material in hot water and performing liquid chromatography and high-resolution mass spectrometry analyses.

Organic astrochemist and study co-author Yoshinori Takano of the Japan Marine-Earth Science and Technology Agency (Jamstec) said he is now looking forward to the results of analyzes of samples that will return to Earth in September from another asteroid. The US space agency, NASA, during its 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 is about 900 meters in diameter and classified as a near-Earth asteroid. Compound concentrations were higher at one site than the other.