Dust grains brought to Earth by NASA’s Stardust spacecraft probably originated in the interstellar dust stream, which comes from outside the solar system, researchers have concluded.
With the help of amateur participants, scientists said they identified seven dust particles and residues, more than a thousand times smaller than a grain of sand, whose characteristics are consistent with interstellar dust. Understanding what the grains are made of may shed light on the solar system’s formation, since this sort of material is believed to be what generates new stars and planetary systems.
The study, led by Andrew Westphal at University of California, Berkeley, is published in the journal Science. The Stardust spacecraft used giant tiles made out of aerogel and aluminum foil to collect the dust samples. Aerogel is an extremely lightweight synthetic material, sometimes described as “solid smoke.”
“We know from astronomical observations that there is a stream of particles that reaches our Solar System from interstellar space,” the vast areas between stars, Bridges said. “Our results show us what this stardust—from which our Solar System formed—actually is.
“Some of these grains formed in suns predating ours, so we are looking beyond our own Solar System when we study them,” he added. “We have also learnt a lot about how to collect and analyze these tiny grains, which are less than one millionth of a meter in size, which will be important in future missions.”
The findings are based on an analysis of specks collected by NASA’s Stardust mission launched in 1999 to collect dust samples from the comet Wild 2 and return them to Earth for study. Stardust also collected dust coming from the direction of the constellation Ophiuchus, or the Serpent Bearer.
All analysis was non-destructive of the particles, but subsequent tests will ultimately have to destroy some of the particles to confirm their origin conclusively, Westphal said. “We have limited the analyses on purpose,” he added. “These particles are so precious. We have to think very carefully about what we do with each particle.”
Source : world-science.net