Extraterrestrial particles have been found in the container jettisoned from the Hayabusa unmanned space probe that ended a seven-year round trip to the asteroid Itokawa in June, Japan Aerospace Exploration Agency sources said Wednesday.

The jettisoned container landed by parachute in an Australian desert.

An analysis using electron microscopes indicates the particles, measuring 0.001 mm in diameter, feature characteristics that are different from terrestrial materials, they said.

JAXA plans to bring the particles to the SPring8 synchrotron radiation facility in Hyogo Prefecture to check whether they are from the asteroid, about 300 million km from Earth.

The probe was designed to collect dust from the asteroid. But whether this task was accomplished remains uncertain. The Hayabusa suffered operational problems during the historic trip.

Detailed analysis of the particles was originally planned to be released in September, but JAXA in August postponed the release till later this year.

The Hayabusa burned up on re-entry into the atmosphere after releasing the container.