They confirm that asteroid Ryugu contains the basic genetic components of life -

The discovery of DNA and RNA materials millions of kilometers from Earth reveals that important organic molecules could have reached our planet from space.

In the search for answers to how life originated on Earth, a recent study by Japanese physicists turns asteroids into speculation.

A new analysis has confirmed that the fragments recovered from the asteroid Ryugu contain the five canonical nitrogenous bases, the essential components of DNA and RNA, molecules responsible for the storage and transmission of genetic information in all living beings.

The discovery, published by a team led by Toshiki Kogi in the journal Nature Astronomy, supports the theory that the chemical compounds necessary for life can reach Earth from space.

The identified nucleobases -- adenine, cytosine, guanine, thymine, and uracil -- are the basic building blocks of nucleic acids.This time, scientists found not just one, but the entire set in two different samples collected by Japan's Hayabusa-2 mission.As Kuga explained, "That doesn't mean there's life in Ryugu."

A biochemist from Japan's Agency for Marine and Earth Science and Technology explained: "Instead, their presence indicates that ancient asteroids may have produced and preserved important molecules for the chemistry involved in the origin of life."

The Hayabusa 2 mission traveled more than 300 million kilometers to reach the asteroid Ryugu, which has a diameter of about 900 meters, and was able to pick up two rocks weighing only 5 grams.

The return of samples to the planet took place in 2020, allowing scientists to work with material that would never have been exposed to Earth conditions, ensuring that the compounds detected did not come from subsequent contamination.

The first analysis published in 2023 already found uracil, one of the RNA bases, but recent research has confirmed the presence of the entire genetic repertoire.

The discovery becomes more important because, according to the research, it is not an isolated case.First, NASA's OSIRIS-REx mission brought fragments of the asteroid Bennu to Earth, where five core nuclei were also found.

"The discovery of various nucleobases in asteroid and meteorite material suggests that they are widely distributed throughout the solar system, supporting the hypothesis that carbonaceous asteroids contributed to the chemical record before the origin of life on early Earth," the Japanese research team wrote in the Science paper.

The discovery of five bases on Ryugu and Bennu has been compared to two carbon-rich meteorites, Murchison and Orgueil, both of which fell to Earth in the 20th century.The cross-sectional analysis allowed the researchers to compare the amount of each base found in different samples and detect variations associated with the chemical history of each space body.

One of the most remarkable discoveries was the relationship between the proportion of nucleobases and the amount of ammonia, an important ingredient also for the formation of biological molecules.

"Given that no known formation mechanism predicts such a relationship, this discovery may point to an unknown way to form nucleobases in the material alone of the primary system," Koga said in presenting the study.

The importance of this advance lies in the fact that nucleobases are essential to life as we know it.DNA, with its second helix, creates the blueprint for each organism's body, but RNA acts as a messenger, interpreting and carrying out the DNA's instructions.In both cases, the bases are five—with the difference that DNA uses thymine and RNA uses uracil—it is important for providing basic information.

The scientific community enthusiastically welcomed the discovery."These results do not indicate that life originated in space," explained César Menor Salvan, an astrobiologist at the University of Alcalá."However, with this and the results from Bennu, we have a very clear idea of ​​what organic substances can form under prebiotic conditions at any point in the universe," adds the expert.

The discovery of thymine, in particular, is important to the study of the origin of life.The RNA world hypothesis suggests that RNA arose before DNA, since uracil is considered easy to synthesize under prebiotic conditions.Thymine, which is the chemical form of uracil, is often associated with very advanced biological processes, so its presence in asteroids like Ryugu suggests that both compounds may have formed in space.

The recent findings also bolster the theory of panspermia, which posits that the building blocks necessary for life could have arrived on Earth carried by asteroids and meteorites early in the planet's history.

According to the researchers, the universality of the five nucleobases in the analyzed asteroids leads to the idea that the essential genetic components were present in the solar system long before the first living organisms appeared on Earth.

Evidence of this abundance is not limited to asteroids.The Orgale and Murchison meteorites also contain complete nucleobases, which supports the idea that the synthesis of these elements may be abundant in the carbon-rich bodies scattered throughout the Sun.

Scientists can see the difference in the base rate between the different fragments explained in the specific chemical environment of each asteroid.In the case of Ryugu, there is an abundance of purines (adenine and guanine) and pyrimidines (cytosine, thymine and uracil), while in Bennu, Orgueil and Murchison, the balance is tilted towards one family or another depending on the amount of ammonia present.

Research published in Nature Astronomy highlights that nucleobase fusion may be common in carbon-rich bodies in the Solar System, where they may act as natural vehicles for transporting genetic material to Earth.

"The universal detection of five canonical nucleobases in samples from the carbonaceous asteroids Ryugu and Bennu highlights the potential contribution of these exomolecules to prebiotic molecular evolution and, ultimately, to the organic inventory that allowed the appearance of RNA and DNA," the authors write.

Japan's Hayabusa-2 mission is central to this preparation.Launched in 2014, it traveled 300 million kilometers to land on Ryugu, collecting samples directly from its surface.The device, which arrived on Earth in 2020, allowed researchers to analyze compounds that had never been exposed to Earth's environment, eliminating the possibility of contamination and making the results last longer.

Koga and his team's study also showed that despite the chemical differences found between different asteroid and meteorite fragments, important nucleobases are always present, supporting the hypothesis of an abundance of these compounds in the Solar System.

The contribution of the space projects of Japan and the United States allowed us to continue our knowledge of the chemical origin of life and open new questions about the existence of organisms outside the Earth.

For Morgan Cable, a researcher at Victoria University of Wellington, "this discovery has important implications for how important molecules can form first and lead to the foundation of life on Earth."

The discovery of nucleobases in asteroids like Ryugu and Bennu offers a renewed perspective on the possibility that the building blocks for life may have been laid down in space and that Earth picked them up from impacts in the distant past.

The differences between the samples indicate that the chemical environment of each celestial body affects the composition of these compounds, but the universal presence of genetic bases in all of them reinforces the role of asteroids as major players in the early history of the planet.

The study is one of the strongest advances in understanding the chemical origins of life and opens the door to new research into how the ingredients essential to life could have been created and preserved in space long before life existed on Earth.

A journey of 300 million kilometers of unprecedented discovery

The Hayabusa-2 mission by the Japan Aerospace Exploration Agency (JAXA) was able to travel the enormous distance separating Earth from Ryugu and bring back fragments of an asteroid that had never been thoroughly studied before.

A comparison of samples from Ryugu, Bennu, Murchison and Orgueil revealed that the number of nucleobases varies according to the chemical environment of each local body, especially according to the amount of ammonia present.According to Koga, "Since there is no known structural method that predicts such a relationship, this discovery may point to a hitherto unknown pathway for the formation of nucleobases in the early elements of the solar system."

The universality of genetic elements in carbonaceous bodies confirms the idea that life-essential elements have existed since the earliest times of the planet's history.The results of the analysis of space samples lead to a broader view of how basic biological structures may have been created and maintained outside of Earth, and the possibility of similar processes occurring in other parts of the universe.

Implications for science and the future of space research

The discovery of five nucleobases in uncontaminated asteroid samples lays a solid foundation for future studies of the origin of life and the synthesis of biological molecules in space.The work of Koga and his team, supported by contributions from international scientists, suggests that the ingredients necessary for life are not only abundant in the solar system, but can also form under different chemical conditions.

The scientific community believes that the progress achieved thanks to the Hayabusa-2 and OSIRIS-REx missions opens up new questions about chemical evolution in the cosmos.

The research marks a new step in the understanding of the origin of life and reinforces the importance of asteroids as potential carriers of basic ingredients for biological evolution on the planet.