A sample from an asteroid far from Earth has confirmed that RNA nucleobases can be found in space rocks.
An analysis of the dust transported from the Ryugu asteroid into the house has been found uracil – one of the four nuclear bases that make up RNA – plus niacinIt is a form of vitamin B3 that plays an important role in metabolism.
This adds to a growing body of evidence that the building blocks of life form in space, and may have been delivered at least in part to Earth by asteroid bombardments early in our planet’s history.
“Scientists have previously found nucleobases and vitamins in some carbon-rich meteorites, but there has always been the issue of contamination through exposure to the Earth’s environment,” says astrophysicist Yasuhiro Ohba from Hokkaido University in Japan.
“Since the Hayabusa2 spacecraft collected two samples directly from the asteroid Ryugu and delivered them to Earth in sealed capsules, contamination can be ruled out.”
How life originated, and how common this occurrence is across the Milky Way, are two questions that humanity would like to know answered. One way to interrogate them is to search for the building blocks of life in space, and explore possible mechanisms for their deliverance from them. outside to down here.
As we increasingly discover, the building blocks of life out there are plentiful. They’ve been spotted in the dust that forms a planet, and in the star-forming clouds of dust that blanket the core of our galaxy. It was found in many meteorites that penetrated the earth’s atmosphere and fell to the ground.
Taken together, the evidence suggests that the building blocks of life may indeed have been alien…but certainty has remained elusive until scientists can rule out the intrusion of Earth’s material into space rocks after they get here.
To find out what was in the original samples Hayabusa2 brought back from Ryugu, Ohba and his colleagues used a new technique they developed to detect on a small scale and identify nucleobases in trace amounts.
The team took two samples, obtained from different locations on the asteroid, soaked them in hot water, and subjected them to high-performance liquid chromatography coupled with Electrospray ionization High resolution mass spectrometry. This technology, when used on the Murchison meteorite that fell to Earth in 1969, produced all five canonical nuclear bases.
The researchers believe that the range of biomolecules found in Ryugu was smaller, but still significant.
“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,” Oppa says. “Other biological molecules were also found in the sample, including a selection of amino acids, amines and carboxylic acids found in proteins and metabolites, respectively.”
The identified compounds, which join about 20 amino acids previously found in the Ryugu samples, differ from those in other carbon-rich meteorites that have fallen to Earth, but are broadly similar. This indicates that biomolecules may be very common in carbonaceous meteorites, and could have reached Earth during periods of bombardment.
As to how they got into the asteroids, scientists think the nitrogen-containing compounds may have formed from simpler molecules, including formaldehyde, ammonia, and hydrogen cyanide.
These were not found in the Ryugu samples, but it is likely that they would have been present if, early in its history, the comet, the asteroid or its parent body had been covered in ices rich in these particles.
However, Ryugu is just the beginning. NASA has collected a sample from another asteroid, Bennu, and is bringing it back to Earth for analysis. Early studies indicate that it also contains organic substances that are compatible with the building blocks of life.
“The discovery of uracil in samples from Ryugu lends strength to current theories regarding the source of nuclear bases in the early Earth,” Oppa says.
“NASA’s OSIRIS-REx mission will return samples from Bennu this year, and a comparative study of the composition of these asteroids will provide more data to build on these theories.”
The stellar stuff we’ve made seems to have been deflected by asteroids.
Research published in Nature Communications.
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