Multiple amino acids – known as ‘the building blocks of life – have been detected in dust brought back from an asteroid by Japan’s Hayabusa2 space probe.
Japanese researchers say the finding could even mean that there is life beyond Earth.
Amino acids are not evidence of life, but are essential for living things to make proteins.
The Hayabusa2 space probe delivered 5.4 grams of surface material from the Ryugu asteroid to Earth, according to Kyodo News.
The 186-million-mile journey took the probe six years.
Previous analysis of the material suggested the presence of water and organic chemicals, the researchers say.
Asteroids (and the meteors and meteorites that sometimes come from them) are leftovers from the formation of our solar system some 4.6 billion years ago.
Most reside in the main asteroid belt between the orbits of Mars and Jupiter.
Japan’s Aerospace Exploration Agency partnered with universities such as the University of Tokyo to investigate the sample.
Some researchers believe that amino acids may have arrived on ancient Earth on meteorites.
Meteors found on Earth are often contaminated by microorganisms from Earth - so Hayabusa2 collected subsurface materials from the asteroid and delivered them to Earth without contact with air.
Kensei Kobayashi, professor emeritus of astrobiology at Yokohama National University, said: "Proving amino acids exist in the subsurface of asteroids increases the likelihood that the compounds arrived on Earth from space.”
The professor also said that the finding suggested that “life could have been born in more places in the universe than previously thought".
The spacecraft, launched in 2014 from Japan’s Tanegashima space centre, journeyed for four years to the asteroid Ryugu, where it gathered a sample and headed home in November 2019.
Japan’s craft, named for the peregrine falcon, a bird of prey, orbited above the asteroid for a few months to map its surface before landing.
It used small explosives to blast a crater and collected the resulting debris.
After Hayabusa2 dropped off the capsule in 2020, it changed course and headed back into space.
Watch: Discovery of amino acids in asteroid could hint at extraterrestrial life