Analysis of Interstellar Dust Begins
Several years ago, NASA's Stardust mission took to space to collect particles from a comet's tail and possibly interstellar dust, before sending them back to Earth. There have already been many studies published about the particles from the comet's tail, but we are only starting to see analyses done of the much more special interstellar dust grains. Among those institutions studying the dust is Berkeley Lab.
While on its way to the comet, Wild 2 the Stardust spacecraft exposed its collector to space, with the hope of catching some dust particles that may be from outside the Solar System. As you can guess, such particles would be very rare and would provide unique insight into our little corner of the galaxy. To that end, the researchers have examined seven grains that may be interstellar dust using non-destructive techniques. Three of these were found in the aerogel while the other four left pits and residue on the aluminum foil. The two larger grains found in the aerogel surprised the researchers as they had a fluffy composition, like a snowflake, which is counter to the expectation of interstellar particles being dense. They also contained the mineral olivine, which would suggest they came from the disks or outflows of other stars. Three of the particles found in the foil contained sulfur compounds, which are not believed to exist in interstellar dust. Further study will be needed to explain the presence of these compounds.
While the current analyses of these grains will prove very informative, the most important examinations are still in the future. Those are to determine if these grains are indeed from outside the Solar System, but as the experiments would destroy the precious grains, tests are being done on analogs first.
Source: Berkeley Lab