KODIAK, Alaska -- Japanese scientists have concluded the Hayabusa probe limped back to Earth with the first flakes of an asteroid ever returned to terrestrial labs from deep space.

Hayabusa captured this image of asteroid Itokawa in 2005. Credit: JAXA

Particles from one of two sample containers inside Hayabusa's return capsule were collected from the surface of Itokawa, the potato-shaped asteroid surveyed by the spacecraft in late 2005.

The Japan Aerospace Exploration Agency, or JAXA, publicly released the results Tuesday in a written statement.

Analysis with a scanning electron microscope identified about 1,500 grains from one sample catcher as rocky particles, according to the JAXA press release.

"Most of them were judged to be of extraterrestrial origin and definitely from asteroid Itokawa," the statement said.

According to researchers, the composition of Hayabusa's samples was more similar to primitive meteorites than known rocks from Earth. The material matches chemical maps of Itokawa from Hayabusa's remote sensing instruments.

JAXA found concentrations of olivine and pyroxene in the Hayabusa samples, the agency press release said.

The particles are also different from native soils at the mission's launch base in southern Japan and landing site in Woomera, Australia.

After Hayabusa's return to Earth in June, scientists opened up the craft's sample container and discovered rocky grains. But confirmation of the material's origin did not come until this week.

Officials retrieved the particles with a special spatula inside a curation facility at Sagamihara, Japan.

Scientists used a special spatula to retrieve particles from the sample canister. Credit: JAXA

Further study of the samples will wait until 2011 because officials are still developing special handling procedures to avoid contaminating the particles during the next phase of research.

Most of the particles are smaller than 10 micrometers.

Scientists have not analyzed samples inside the capsule's other collection chamber, but officials expect it to hold even more material because of its location on the spacecraft.

It lies on the side of the spacecraft that touched Itokawa with the most force during its time at the asteroid, possibly gathering more rock grains.

Hayabusa was designed to collect several hundred milligrams of material if the sampling procedure went as planned, but the craft's projectile gun did not activate when it approached the asteroid.

Scientists expect to learn much about asteroids from even a miniscule sample through powerful tools like scanning electron microscopes.