The capsule brought back by the Hayabusa2 space probe last week contained black particles that may be from a distant asteroid, the Japan Aerospace Exploration Agency said Monday.
Confirmation that the samples are from the Ryugu asteroid will prove that the mission was successful and allow JAXA to conduct further analysis on the origins of life and the solar system.
The space agency said earlier that if the samples share the same black color as Ryugu, it would be almost certain that they were from the asteroid.
Hayabusa2, which left Earth in 2014 to travel millions of kilometers, ultimately touched down on the asteroid twice last year.
The objective was to collect the first-ever asteroid subsurface samples after creating an artificial crater by shooting a copper projectile at Ryugu's surface. The mission was thought to be successful as flying dust and debris were observed.
The samples were brought back to Earth in a sealed metal container within the capsule, which Hayabusa2 successfully dropped on Dec. 6 over an Australian desert.
The retrieved capsule arrived in Japan two days later to be opened at JAXA's Sagamihara Campus in Kanagawa Prefecture, near Tokyo, in a vacuum at a special facility to prevent potential contamination.
Using a light microscope, the space agency plans to spend six months analyzing the samples' volume, color and other characteristics.
Gas samples were also collected from the container in a preliminary analysis conducted in Australia last week and are believed to be from the asteroid.
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