NASA's Cassini Spacecraft Samples 36 Grains of Interstellar Dust

Posted on April 16, 2016

NASA's Cassini spacecraft has sampled interstellar dust. Cassini is currently in orbit around Saturn and it detected the faint signature of dust coming from beyond our solar system. NASA says Cassini has sampled millions of dust grains with its cosmic dust analyzer instrument since 2004 and of these just 36 grains came from interstellar space.

The dust grains were speeding through the Saturn system at speeds over 45,000 mph (72,000 km/h). The dust was traced back to the local interstellar cloud, which is a nearly empty bubble of gas and dust our solar system is traveling through.

Nicolas Altobelli, Cassini project scientist at ESA (European Space Agency) and lead author of the study, says in a statement, "We knew that if we looked in the right direction, we should find them. Indeed, on average, we have captured a few of these dust grains per year, travelling at high speed and on a specific path quite different from that of the usual icy grains we collect around Saturn."

Cassini analyzed the composition of the dust and found that the grains were a mixture of minerals. These included magnesium, silicon, iron and calcium. There were also reactive elements like sulfur and carbon. The author says the interstellar gains of dust "lack carbon-bearing compounds and have been homogenized in the interstellar medium into silicates with iron inclusions."

NASA says stardust grains are also sometimes found in meteorites, which have preserved them since the birth of our solar system. A research paper on the study was published here in the journal, Science.

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