More molecules crucial for the formation of life on Earth found on asteroid Ryugu

More evidence important building blocks for life are created in space and could have been delivered to Earth by meteorites

The finding contributes to the growing body of evidence that essential components for life originate in space and may have been transported to Earth via meteorites. Specifically, the Hayabusa2 mission’s analysis of samples from the asteroid Ryugu revealed the presence of nitrogenous organic compounds, including uracil, a nucleobase integral to RNA.

A team of international researchers, headed by Associate Professor Yasuhiro Oba at Hokkaido University, has examined samples collected from the asteroid Ryugu by Japan’s Hayabusa2 spacecraft.

They have discovered uracil, a crucial component of RNA, which contains the genetic instructions for constructing and maintaining living organisms. In addition, nicotinic acid, also known as Vitamin B3 or niacin, an essential cofactor for metabolism in living organisms, was also identified in the same samples.

This new finding supports the idea that fundamental building blocks for life are generated in space and could have been transferred to Earth via meteorites.

The study has been published in the journal Nature Communications.

“Scientists have previously found nucleobases and vitamins in certain carbon-rich meteorites, but there was always the question of contamination by exposure to the Earth’s environment,” explains Oba. “Since the Hayabusa2 spacecraft collected two samples directly from asteroid Ryugu and delivered them to Earth in sealed capsules, contamination can be ruled out.”

To extract these molecules, they immersed the Ryugu particles in heated water and conducted analyses using high-resolution mass spectrometry combined with liquid chromatography. Through this process, they detected the existence of uracil, nicotinic acid, and other organic compounds that contain nitrogen.

“We found uracil in the samples in small amounts, in the range of 6–32 parts per billion (ppb), while vitamin B3 was more abundant, in the range of 49–99 ppb,” Oba adds. “Other biological molecules were found in the sample as well, including a selection of amino acids, amines and carboxylic acids, which are found in proteins and metabolism, respectively.”

Although the detected compounds bear some similarities to those previously found in meteorites that are rich in carbon, they are not identical.

The research team speculates that the difference in concentration between the two samples, which were taken from distinct locations on Ryugu, is likely due to their exposure to the harsh conditions of space. They also suggest that the nitrogenous compounds may have been generated, at least partially, from simpler molecules such as ammonia, formaldehyde, and hydrogen cyanide, even though these compounds were not found in the Ryugu samples. However, they are known to exist in cometary ice, which raises the possibility that Ryugu could have originated as a comet or another parent body that existed in low-temperature environments.

“The discovery of uracil in the samples from Ryugu lends strength to current theories regarding the source of nucleobases in the early Earth,” concludes the researcher. “The OSIRIS-REx mission by NASA will be returning samples from asteroid Bennu this year, and a comparative study of the composition of these asteroids will provide further data to build on these theories.”

Source: 10.1038/s41467-023-36904-3 

Image Credit: NASA Goddard/JAXA/Dan Gallagher