(Artist’s concept of the Stardust spacecraft – Photo Credit: NASA/JPL-Caltech)
Scientists believe that seven microscopic particles of dust, collected by NASA’s comet-chasing Stardust spacecraft, originated from outside of our solar system, signalling the world’s first examination of interstellar dust.
If the scientists are right, the NASA spacecraft has brought materials from outside the solar system back to Earth. While the scientists say that more tests are needed, they are confident enough to publish a paper on the findings.
The rare, microscopic interstellar dust particles, that date back to the beginnings of the solar system, were collected by NASA’s Stardust spacecraft who returned the samples back to Earth in 2006. A team of scientists have since meticulously combed through the spacecraft’s dust collectors, and it appears that their efforts have paid off.
Scientists identified seven particles that were likely to have an interstellar origin.
“They are very precious particles” said Dr Andrew Westphal, the study’s lead researcher.
”Fundamentally, the solar system and everything in it was ultimately derived from a cloud of interstellar gas and dust. We’re looking at material that’s very similar to what made our Solar System” he added.
The particles are believed to have been created by a supernova explosion millions of years ago.
(This image shows a dust particle impact on one of the craft’s foil collectors – Photo Credit: AP/Science via Stardust ISPE/NRL)
“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 at NASA’s Johnson Space Centre in Houston.
The Stardust spacecraft was launched in 1999 and flew through the coma – an atmosphere of gas and dust – surrounding the Wild-2 comet in January 2004, coming within 149 miles of the icy body.
(Comet Wild-2 photographed by Stardust – Photo Credit: NASA/Stardust)
Using a ”fly paper” technique, Stardust captured cometary dust in tiles of soft aerogel separated by pieces of aluminium foil. A similar collector was placed on the rear of the probe to collect particles from streams of interstellar dust.
The probe returned the dust collectors to Earth on January 15th, 2006. They landed at the Utah Test and Training Range near Salt Lake City, delivering the interstellar samples to eager teams of scientists and ending the craft’s seven-year, three-billion-mile journey.
Analysis revealed that three particles of interstellar material left traces within the aerogel material while the remains of four others were discovered within pits in the aluminium foil.
(A scientist observing the craft’s dust collectors – Photo Credit: Andrew Westphal/UC Berkeley)
The particles found on the craft’s collectors are much more diverse, in terms of chemical composition and structure, than scientists expected. The smaller particles differ greatly from the larger ones and appear to have varying histories.
The particles are around a tenth of the size of comet dust, measuring up to two thousandths of a millimetre across. Some of the larger ones even had a snowflake-like ”fluffy” structure.
Supernovas, red giants and other evolved stars are thought to produce interstellar dust while also generating heavy elements like carbon, nitrogen and oxygen which are necessary for life.
Two particles collected by the craft, dubbed Orion and Hylabrook, will now undergo further tests to determine their oxygen isotope quantities, which could provide even stronger evidence for their extrasolar origin.
The Solar System & Beyond 