LOS ANGELES – The first dust samples ever retrieved from an asteroid and brought back for study show that a portion of the most common meteorites to hit Earth may have come from a single rocky ancestor out in space, Japanese researchers say.

In a wide-ranging analysis of tiny fragments collected from the asteroid Itokawa during a spacecraft visit in 2005, six studies by several teams of scientists released Thursday by the journal Science piece together a detailed description, and history, of this particular space rock.

The more than 1,500 dust grains gathered by Japan’s Hayabusa spacecraft show that meteorites contain the primitive elements that formed the early solar system.

That knowledge will allow scientists to better understand what our part of the Milky Way looked like billions of years ago when the ring of gas and dust surrounding the sun began to coalesce to form planets, asteroids and comets.

“These dust particles are the building blocks of the planets,” said Tomoki Nakamura, a planetary scientist at Tohoku University in Sendai, Japan, who is one of the studies’ lead authors.

The fact that Hayabusa returned any particles at all is a small miracle in itself. Launched in 2003, the spacecraft was designed to shoot an impactor into the surface of the asteroid Itokawa and then scoop up dust kicked up by the collision.

The impactor failed to fire; but the mission scientists got the craft to at least touch the asteroid’s surface.

“They didn’t know whether they trapped any particles or not,” said Alexander Krot, a cosmochemist at the University of Hawaii at Manoa. “Before it returned to Earth, they didn’t even know whether it was successful.”