Imperial College London scientists say microbes on asteroid samples from Japan's Hayabusa 2 mission have down to Earth origins.

Asteroid Ryugu was altered by water and contains organic molecules older than the Sun. The building blocks of RNA and Vitamin B3 have been found in its samples, together with polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, a molecule used in mothballs. Earthly bacteria don’t seem to care where the molecules originated from.

Scientists have found microorganisms crawling over a sample retrieved from the 200 million-mile-distant asteroid Ryugu. But they almost certainly came from Earth.

Asteroids are remnants of the formation of our solar system, and while many can be found within the asteroid belt between the orbits of Mars and Jupiter, some cannot. One such object is asteroid (162173) Ryugu,

Japanese researchers have identified sodium carbonates, or salt crystals, in samples from the Ryugu asteroid brought back to Earth by the Hay･･･