NASA's Cassini spacecraft is collecting dust. No, the giant bus-sized probe is not on some alien’s mantle, but it is collecting alien dust. Scientists analyzing data on the dust particles Cassini has picked up have determined that at least 36 of them are from outside our solar system, originating from somewhere in interstellar space and passing through at a high speed.
We’re all familiar with dust, so it’s pretty impressive that Cassini has the onboard technology to not only collect icy dust particles from Saturn and its moons, but to analyze their compositions individually and locate their point of origin. Most have been traced back to Enceladus, a geologically active moon. However, according to a report in the journal Science, 36 grains have been identified as cosmic dust.
Cosmic dust is produced when stars die, but with the vast range of types of stars in the universe, we naturally expected to encounter a huge range of dust types over the long period of our study.
That’s study co-author Frank Postberg of the University of Heidelberg, partner investigator of Cassini’s dust analyzer (nice work if you can get it) explaining the alien dust. The particles were identified as cosmic dust by their composition – instead of the usual ice, they were filled with hard elements like magnesium, silicon, iron and calcium while lacking sulfur and carbon. In addition, the particles appear to be young in age when compared to similar particles found in meteorites on Earth.
The cosmic dust particles also gave away their identity by their high speed and the fact that they didn’t stick around long. They were measured at 45,000 mph (72,000 km per hour), a speed that allowed them to pass by without being pulled into the orbit of Saturn, the sun or any other bodies in the solar system. Well, until they slammed into Cassini's Cosmic Dust Analyzer.
Cassini's 20-year mission is scheduled to end on September 15, 2017, when it crashes and burns in Saturn’s atmosphere. It sounds like Nicolas Altobelli, Cassini project scientist at ESA (European Space Agency) and lead author of the study, is going to miss it.
The long duration of the Cassini mission has enabled us to use it like a micrometeorite observatory, providing us privileged access to the contribution of dust from outside our solar system that could not have been obtained in any other way.