Samples gathered from the near-Earth asteroid Ryugu have been found to include all five nucleobases, which are the essential components of life, reinforcing the likelihood that life’s precursors may exist beyond our planet. Scientists suggest that asteroids like Ryugu could have played a vital role in providing these crucial molecules to Earth, possibly igniting the emergence of life.
The Japan Aerospace Exploration Agency (JAXA) launched its Hayabusa 2 mission in December 2014, focusing on the carbon-rich asteroid Ryugu. The mission successfully touched down on the asteroid’s surface twice in 2019 to gather samples, which returned to Earth in December 2020. An initial analysis of these samples revealed the nucleobase uracil, in addition to nicotinic acid (vitamin B3), its derivatives, and a variety of imidazoles.
Comprehensive analyses by Japanese researchers on two further samples from the Ryugu mission utilized high-performance liquid chromatography and high-resolution mass spectrometry. These methods identified all five nucleobases: adenine, guanine, cytosine, thymine, and uracil. Remarkably, the samples showed a nearly equal ratio of purines (adenine and guanine) to pyrimidines (cytosine, thymine, and uracil), in contrast to other extraterrestrial samples, which frequently display a preference for one nucleobase type.
The researchers speculate that high-energy radiation may trigger the conversion of simple nitrogen-containing compounds—like hydrogen cyanide—into nucleobases. Asteroids, having formed within the solar system, might have conveyed these vital molecules to primitive Earth, thereby possibly aiding in prebiotic molecular evolution and the eventual creation of RNA and DNA. Such discoveries strengthen the idea that the building blocks of life could exist beyond Earth, suggesting a wider realm for the origins of life in the solar system.