A Japanese spacecraft is nearing Earth after a yearlong journey home from a distant asteroid with soil samples and data that could provide clues to the origins of the solar system. The Hayabusa2 spacecraft left the asteroid Ryugu, about 180 million miles from Earth, a year ago and is expected to reach Earth and drop a capsule containing the precious samples in southern Australia on Dec. 6.

Scientists at the Japan Aerospace Exploration Agency believe the samples, especially those taken from under the asteroid's surface, contain valuable data unaffected by space radiation and other environmental factors. “Organic materials are origins of life on Earth, but we still don't know where they came from,” Yoshikawa said. “We are hoping to find clues to by analyzing details of the organic materials brought back by Hayabusa2."

JAXA, the space agency, plans to drop the capsule containing the samples onto a remote, sparsely populated area in Australia from 136,700 miles away in space, a big challenge requiring precision control. The capsule, protected by a heat shield, will turn into a fireball during re-entry in the atmosphere at 125 miles above ground. At about 6 miles above ground, a parachute will open to prepare for landing, and beacon signals will be transmitted to indicate its location.

Hayabusa2 touched down on Ryugu twice, despite its extremely rocky surface, and successfully collected data and samples during the 1½ years after it arrived there in June 2018. Scientists said there are traces of carbon and organic matter in the asteroid soil samples. JAXA hopes to find clues to how the materials are distributed in the solar system and are related to life on Earth. Asteroids, which orbit the sun but are much smaller than planets, are among the oldest objects in the solar system and therefore may help explain how Earth evolved.