Collected aboard the Stardust spacecraft, which returned to Earth in 2006, the seven microscopic particles were found by scientists carefully sifting through the satellite’s aerogel and aluminum foil dust collectors.
Launched in 1999 from the Utah Test and Training range, 80 miles west of Salt Lake City, the Stardust mission transported a tennis racket-sized collection canister to within 149 miles of a comet in 2004.
During this flyby the Stardust collection canister exposed its aerogel center to the trailing end of the comet, picking up various debris transported by the icy rock.
Though the Stardust spacecraft returned to earth eight years ago, scientist are only now drawing conclusions about what they may have discovered; yet even those findings are tenuous.
“These are the most challenging objects we will ever have in the lab for study, and it is a triumph that we have made as much progress in their analysis as we have," said Michael Zolensky, curator of the Stardust laboratory.
Much of the ongoing debate around Stardust’s findings concerns the varied nature of the craft’s particles. While scientists expected a rather homogenous return, Stardust delivered particles of diverse size and chemical composition. In fact, three of the seven most scientifically important dust granules contain sulfur compounds which some researchers say don’t occur in interstellar dust.
While researchers continue their exploration of these microscopic materials they will continue to focus on the particles they expect to find in interstellar dust.
As the Universe’s most powerful material producers, supernovas, red giants and other evolving stars pour carbon, nitrogen and oxygen elements into the interstellar medium. In their continued search to determine whether the Stardust’s particles are remnants of the Universe’s interstellar history, researchers plan to study a couple of promising particles to determine their oxygen isotope quantities. If their isotope saturation levels meet a certain threshold scientists will have further evidence that they’ve finally discovered interstellar dust.
Image Courtesy of NASA