Scientists Discover RNA Component Buried in The Dust of an Asteroid

The presence of RNA nucleobases in space debris has been verified by a sample taken from an asteroid far from Earth.

Uracil, one of the four nucleobases that make up RNA, has been discovered in dust brought home from the asteroid Ryugu, along with niacin, a type of vitamin B3 that is crucial for digestion.This supports an increasing body of data suggesting that the components for life exist in space and may have been brought to Earth in part by an early asteroid impact.

Astrochemist Yasuhiro Oba of Hokkaido University in Japan says, "Scientists have previously found nucleobases and vitamins in some carbon-rich meteorites, but there was always the question of contamination by exposure to the Earth's environment."

Contamination can be ruled out because the Hayabusa2 mission immediately gathered two samples from the asteroid Ryugu and sent them to Earth in sealed capsules.

Humanity is eager to learn the details of how life first appeared and how widespread it may have been throughout the Milky Way cosmos. One method of questioning them is to look for the components of life in space and consider methods for bringing them to earth.

There are many components for living out there, as we are learning more and more. They have been discovered in masses of star-forming dust that envelop the center of our galaxy as well as in planet-forming dust. And they have been discovered in numerous meteors that have impacted the earth after leaving Earth's atmosphere.

Together, the data points to the possibility that life's fundamental components may have been extraterrestrial. But until scientists could rule out the permeation of Earth material into space rocks after they arrived here, confidence stayed illusive.

Oba and his coworkers used a novel method they devised for the small-scale detection and labeling of nucleobases in minute quantities to determine what was in the pure samples Hayabusa2 returned from Ryugu.

The researchers used high-performance liquid chromatography in conjunction with electrospray ionization high-resolution mass spectrometry to analyze the two samples, which were taken from various parts of the asteroid. This method produced all five standard nucleobases when applied to the 1969 Murchison asteroid that impacted Earth.

The experts think the lesser but still important variety of biomolecules discovered in Ryugu.

Uranium was only present in trace quantities in the samples, between 6 and 32 parts per billion (ppb), while vitamin B3 was more prevalent, between 49 and 99 ppb, according to Oba. Other organic compounds, such as a variety of amino acids, amines, and carboxylic acids, which are present in proteins and metabolism, respectively, were also discovered in the sample.

The newly discovered substances, which join the roughly 20 amino acids already discovered in Ryugu samples, are distinct from those discovered in other carbon-rich asteroids that have impacted Earth but are largely comparable. As a result, it is possible that proteins are widely distributed in carbonaceous meteorites and may have traveled to Earth during times of impact.

Scientists think that substances containing nitrogen may have developed from simpler molecules like formaldehyde, ammonia, and hydrogen cyanide as to how they ended up on the meteorites.

These have not been discovered in the Ryugu samples, but they may have been there if the asteroid or its parent body had once been a comet that had been covered in ices rich in these compounds early in its existence.

But Ryugu is only the beginning. NASA has taken a sample from Bennu, another asteroid, and is returning it to Earth for examination. Early research suggests that it also includes organic substances that are compatible with the components of life.

According to Oba, the discovery of uracil in the Ryugu samples "gives support to the current theories regarding the source of nucleobases in the early Earth."

This year, NASA's OSIRIS-REx mission will return fragments from the asteroid Bennu, and a comparison of the asteroids' compositions will add more evidence to support these hypotheses.

It appears that the star material from which we are formed took a diversion through asteroids.

The research has been published in Nature Communications.