Dust is a major annoyance for most of us, but to scientists it can be precious. Over the summer researchers identified seven specks of dust returned to Earth by the Stardust spacecraft, which spent 12 years in space and tried to collect samples from the wake of a comet. The seven dust motes may come from interstellar space. Determining their true origin, however, has proven problematic.
Three of the microscopic grains are locked in a foam material called aerogel, from the outside covering of Stardust. Aerogel is great at catching the particles, but scientists have not yet figured out a good way to extract the grains without damaging them. For now, the grains, and the researchers, are stuck.
The other four interstellar dust candidates were found in the grid of aluminum foil that held the aerogel. When the grains hit, the foil melted and formed miniature craters. Scientists chemically analyzed two of these craters, but the findings are inconclusive.
The impactors might come from interstellar space, or they could be local. Unfortunately, the analysis destroyed those two grains. And the other two foil-embedded candidates were lost while being transported between labs.
Scientists hope to find still more microscopic particles in the Stardust collector. And they have keep NASA cleaning crews from doing any dusting.