The compounds discovered include niacin, which is also known as vitamin B3, and uracil - one of the four nucleobases (nitrogen-containing compounds), that make up RNA, the molecules that contain the instructions of how to build living organisms.
“Scientists have previously found nucleobases and vitamins in certain carbon-rich meteorites, but there was always the question of contamination by exposure to the Earth's environment,” said lead researcher Prof Yasuhiro Oba, of Hokkaido University.
“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.”
Hayabusa2 was launched in December 2014 by the Japanese space agency JAXA. It reached its target, the space rock Ryugu, in June 2018, stayed for a year and a half to gather samples, and returned them to Earth in December 2020.
The team extracted the compounds by soaking samples taken from Ryugu in hot water and analysing them with a high-resolution mass spectrometer. As well as uracil and niacin, they also found several other biologically important molecules, including a selection of amino acids, amines and carboxylic acids, which are found in proteins and play a role in the metabolism of living things.
The compounds likely formed from simpler molecules such as ammonia, formaldehyde and hydrogen cyanide, which are all commonly found in cometary ice, the researchers say.
The finding adds further credence to the theory of panspermia – the hypothesis that important building blocks for life are created in space and could have been brought to Earth by meteorites.
“The discovery of uracil in the samples from Ryugu lends strength to current theories regarding the source of nucleobases in the early Earth,” said Oba.
“The OSIRIS-REx mission by NASA will be 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.”
Jason GoodyerCommissioning editor, BBC Science Focus
Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.
