Researchers found seven dust motes on NASA's Stardust spacecraft that most likely came from outside of our solar system.
The dust may have been created in a super nova explosion millions of years ago and were altered on eons of exposure to extreme space UC Berkeley reported.
"They are very precious particles," said Andrew Westphal, a physicist at UC Berkeley's Space Sciences Laboratory.
Further testing will be needed to confirm the dust particles are actually from interstellar space, but if they are the findings could help explain the origin of interstellar dust.
The particles proved to be much more diverse in chemical composition than had been expected. The small ones are much different than the large ones; some of the large ones have a fluffy structure resembling a snowflake.
"The fact that the two largest fluffy particles have crystalline material - a magnesium-iron-silicate mineral called olivine - may imply that these are particles that came from the disks around other stars and were modified in the interstellar medium," Westphal said. "We seem to be getting our first glimpse of the surprising diversity of interstellar dust particles, which is impossible to explore through astronomical observations alone."
Stardust was launched in 1999 to fly through dust emitted by the comet Wild-2. Collectors on the rear were positioned to capture the "snowstorm of interstellar dust streaming through the galaxy," said UC Berkeley research physicist Anna Butterworth.
"This dust is relatively new, since the lifetime of interstellar dust is only 50 to 100 million years, so we are sampling our contemporary galaxy," Butterworth continued. The dust collectors were dropped to Earth by parachute in 2006 and scientists at the Johnson Space Center scanned the panels at varying depths through a transparent aerogel and turned these scans into movies.
"We expected to find grains less than a micron across that would leave a track a couple of microns wide. That is about one-fiftieth the width of a human hair. We might not see the particles in an optical microscope, so the Dusters are looking for the impact tracks they made," Butterworth said.
Several dusters were tracked and vetted. The dusters found 69 tracks while Westphal found two. Thirty-one of these were extracted with their surrounding aerosols to be shipped UC Berkeley to be analyzed by a scanning transmission x-ray microscope, or STXM.
The findings were published in the Aug. 15 edition of the journal Science. Twelve other papers on the particles will appear next week in the journal Meteoritics & Planetary Science.