Japan space probe carrying asteroid rocks arrives on Earth

A Japanese space probe carrying the first extensive samples of an asteroid has completed its six-year mission, landing safely in the remote Australian outback, Japan's space agency said on Sunday.

The samples, collected from a distant asteroid and expected to amount to no more than 0.1 grams of material, were dropped off by Japanese space probe Hayabusa-2.

The mission seeks to answer some fundamental questions about the origins of the solar system and where molecules like water came from.

The capsule carrying samples entered the atmosphere just before 2:30 am Japan time (1730 GMT Saturday), creating a shooting-star-like fireball as it entered Earth's atmosphere.

The spacecraft, launched from Japan's Tanegashima space centre in 2014, took four years to reach the asteroid Ryugu before taking a sample and heading back to Earth in November 2019.

"The helicopter carrying the capsule arrived at local headquarters and the capsule was brought inside the building," the agency said on Twitter.

The capsule separated from Hayabusa-2 on Saturday, when the refrigerator-sized space probe that launched into space in 2014 was 220,000 kilometres (137,000 miles) away from Earth.

It landed in the southern Australian desert, where it will be recovered from an area spanning some 100 square kilometres, with search crews guided by beacons emitted as the capsule descended.

Scientists at the Royal Australian Air Force's (RAAF) Woomera Range Complex in South Australia closely monitored the capsule's descent.

Samples in the capsule were collected from the asteroid Ryugu, some 300 million kilometres from Earth during two crucial phases of Hayabusa-2's mission last year.

The probe collected both surface dust and pristine material from below the surface that was stirred up by firing an "impactor" into the asteroid.

The material collected from the asteroid is believed to be unchanged since the time the universe was formed.

Scientists are especially keen to discover whether the samples contain organic matter, which could have helped seed life on Earth.

Half the material will be shared between JAXA, US space agency NASA and other international organisations, and the rest kept for future study as advances are made in analytic technology.

(with inputs from agencies)