A Japanese spacecraft is on its intended trajectory, space agency officials said, as it approaches Earth to deliver a capsule containing samples from a distant asteroid that could provide clues to the origin of the solar system and life on Earth.

Hayabusa2 left the asteroid Ryugu, about 180 million miles away, a year ago. The capsule is to be released 136,700 miles away in space and land in a remote, sparsely populated area of Woomera, Australia, on Sunday.

Hayabusa2 is flying smoothly according to plan, Yuichi Tsuda, project manager at the Japan Aerospace Exploration Agency (JAXA), said at a briefing ahead of the critical separation of the capsule from the spacecraft on Saturday.

Hyabusa 2 capsule return
(PA Graphics)

“We trained ourselves and now we are fully prepared. So I’m just praying that equipment that hasn’t been used yet will work well and that there will be good weather in Australia,” he said. “We are so excited.”

In the early hours of Sunday, the capsule, protected by a heat shield, will briefly turn into a fireball as it re-enters the atmosphere 75 miles above Earth. At about six miles above ground, a parachute will open to slow its fall and beacon signals will be transmitted to indicate its location.

JAXA staff have set up satellite dishes at several locations in the target area to receive the signals, while also preparing marine radar, drones and helicopters to assist in the search and retrieval of the pan-shaped capsule, which is 15in in diameter.

Japan Asteroid
Crew members set up an antenna in Woomera, South Australia (JAXA/AP)

Scientists say they believe the samples, especially ones taken from under the asteroid’s surface, contain valuable data unaffected by space radiation and other environmental factors. They are particularly interested in analysing organic materials in the samples.

JAXA hopes to find clues to how the materials are distributed in the solar system and are related to life on Earth.

For Hayabusa2, it is not the end of the mission started in 2014. After dropping the capsule, it will return to space and head to another distant small asteroid called 1998KY26 on a journey slated to take 10 years one way.

Japan Asteroid
An image of Ryugu taken by Hayabusa2 (JAXA/AP)

So far, its mission has been fully successful. It touched down twice on Ryugu, despite an extremely rocky surface, and collected data and samples during the 18 months it spent near Ryugu after arriving in June 2018.

In its first touchdown in February 2019, it collected surface dust samples. In a more challenging mission in July that year, it collected underground samples from the asteroid for the first time in space history after landing in a crater that it created earlier by blasting the asteroid’s surface.

Asteroids, which orbit the sun but are much smaller than planets, are among the oldest objects in the solar system and may help explain how Earth evolved.

Ryugu in Japanese means Dragon Palace, the name of a sea-bottom castle in a Japanese folk tale.