Scientists Make A Shocking Discovery Of RNA Molecules In Asteroid Dust Sample

hero ryugu at night
Researchers have found RNA nucleobases in samples retrieved from asteroid Ryugu. The samples were collected by the Japanese Space Agency's Hayabusa2 spacecraft, which harvested the samples in 2019 before returning to Earth in 2020.

An international team led by Associate Professor Yasuhiro Oba at Hokkaido University has been studying the samples from asteroid Ryugu since the samples were returned. What they have found is that the space rock contained uracil, one of the informational units (nucleobases) that makes up RNA, according to a recent post on Eureka Alert. The discovery provides evidence to support the possibility that important building blocks for life could have been brought to Earth by meteorites.

ryugu samples
Ryugu samples collected by Hayabusa2 spacecraft.

"Scientists have previously found nucleobases and vitamins in certain carbon-rich meteorites, but there was always the question of contamination to the Earth's environment," Oba remarked. "Since the Hyubusa2 spacecraft collected the two samples directly from the asteroid Ryugu and delivered them to Earth in sealed capsules, contamination can be ruled out."

The team was able to extract the molecules from the samples by soaking the Ryugu particles in hot water, and then analyzing them with liquid chromatography coupled with high-resolution mass spectrometry. The process unveiled the traces of uracil and nicotinic acid, along with other nitrogen-containing organic compounds.

ryugu chemical makeup
A conceptual image for sampling materials on the asteroid Ryugu containing uracil and niacin by the Hayabusa2 spacecraft (NASA Goddard/JAXA/Dan Gallagher).

Uracil was found in small amounts, in the range of 6-32 parts per billion (ppb). Vitamin B3 was found in a larger amount, in the range of 49-99 ppb. Oba stated that other biological molecules were also found in the samples, "including a selection of amino acids, amines and carboxylic acids, which are found in proteins and metabolism."

There were differences in the makeup of the two samples from Ryugu. Researchers hypothesize that the reason for this is due to the exposure to the extreme environments of space. They also think that the nitrogen-containing compounds, in part at least, formed from the simpler molecules, such as ammonia.

Oba believes the discovery of uracil in the samples give credence to current theories in regard to the source of nucleobases in the early stages of Earth's history. He concluded, "The OSIRIS-REx mission by NASA will 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."