Stardust Spacecraft May Have Captured Tiny Dust Grains from Interstellar Space

First Posted: Aug 15, 2014 06:57 AM EDT

Seven tiny grains of dust captured by the NASA Stardust spacecraft may just be from interstellar space. Scientists have taken a closer look at these rare, microscopic particles and have discovered that they probably came from outside our solar system, possibly created in a supernova explosion millions of years old.

These particles are extremely rare and, if from interstellar space, could help explain the origin and evolution of interstellar dust. Interestingly, the researchers found that these particles are far more diverse in terms of chemical composition and structure than previously thought. For example, the small ones are much more different than the larger ones, and may have had different histories. In addition, many of the larger particles have a fluffy structure, rather like 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," said Andrew Westphal, one of the researchers, in a news release. "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."

The particles were first discovered thanks in part to citizen science. Volunteers, calling themselves "Dusters," scanned more than a million images through Stardust@home, a UC Berkeley citizen-science project. In all, scientists don't expect to find more than about 12 particles of interstellar dust amongst all of the other samples.

"Their diversity was a surprise, but also these fluffy particles, sort of like a tossed salad, were complex, an agglomeration of other particles, rather than one dense particle suggested by the simplest models of interstellar particles," said Rhonda Stroud, one of the researchers, as she described the particles' structures.

The dust itself is relatively new, since the lifetime of interstellar dust is only about 50 to 100 million years. Yet the samples could tell researchers quite a bit about our universe. Currently, "Dusters" are still combing archives in order to find evidence of even more particles which could lead to future discoveries.

The findings are published in the journal Science.

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