Japan's Hayabusa2 space mission, which brought to Earth samples from an asteroid in late 2020, has found more than 20 types of amino acids in it, according to Japanese space agency JAXA officials.

In 2018, Hayabusa2 landed atop a moving asteroid named Ryugu and collected particles from above and below its surface.

In December 2020, it returned to Earth with a sealed capsule containing about five grams of dust and rock.

Although it is not known how amino acids arrived on ancient Earth, one theory says they were brought by meteorites, with amino acids being detected in a meteorite found on Earth.

"We previously only had a handful of these rocks to study, and all of them were meteorites that fell to Earth and were stored in museums for decades to centuries, which changed their compositions,"

said geochemist Nicolas Dauphas, one of the three University of Chicago researchers who worked with a Japan-led international team of scientists to analyse the fragments.

Hayabusa2 delivered the subsurface materials to Earth without exposing them to outside air after collecting the samples that had not been weathered by sunlight or cosmic rays.

Hayabusa2 left Earth in 2014 and reached its stationary position above Ryugu in June 2018 after traveling 3.2 billion km on an elliptical orbit around the sun for more than three years.