Japan's space agency said on Monday it has found "minute particles" of what it hopes is asteroid dust in the capsule of the space probe Hayabusa which returned to Earth last month.
Scientists hope any dust samples from the potato-shaped asteroid Itokawa could help reveal secrets about the origins of the solar system.
"We have started the opening process of the sample container of Hayabusa since 24th June, 2010 and confirmed there are minute particles," the Japan Aerospace Exploration Agency (JAXA) said.
But the agency added it remained unclear whether the particles are contaminants from Earth or come from Itokawa which the space probe landed on during its multi-billion-kilometre (mile) journey.
It is expected to take months to get the final results of the analysis.
When Hayabusa was launched in 2003, the canister was open, meaning it may contain materials that originated on Earth, a JAXA spokesman said.
Technical problems plagued the journey of Hayabusa, which at one stage spun out of control and lost contact with JAXA for seven weeks, delaying the mission for three years until the asteroid and Earth re-aligned.
When it finally latched onto the Itokawa asteroid, a pellet-firing system designed to stir up dust malfunctioned, leaving it unclear how much material the probe was able to gather.
After a seven-year space odyssey, the heat-proof pod was fired back to Earth by the Hayabusa probe in June.
Researchers at the Sagamihara Campus near Tokyo, have been opening the multi-layered canister in cooperation with US space agency NASA.
Scientists expect to recover at least some asteroid dust from the world-first mission.
