Interstellar Dust Detected From Spacecraft Studying Saturn

Since 2004, the spacecraft Cassini has been orbiting around Saturn, studying the planet, its rings, as well as its moons. It sampled millions of dust grains that are rich with ice, using its cosmic dust analyzer. As readings showed, these grains originated from active jets from the surface of Enceladus, the planet's geologically active moon.

However, among the many grains collected by the spacecraft, a total of 36 stood out from the crowd - and scientists conclude that these materials actually came from interstellar space or the space between the stars.

Cassini detects interstellar dust at Saturn. Seriously: *Alien dust*! https://t.co/nmLkJqvDxR pic.twitter.com/jvuqtgcIWg

— Phil Plait (@BadAstronomer) April 18, 2016

These dust grains were said to be speeding through Saturn at 45,000 mph, which means they are fast enough to avoid being trapped in the solar system by the gravity of the sun and the rest of the planets.

While the possibility of alien dust is not unanticipated, this is not the first time that they have been seen either. In the 1990s, the ESA/NASA Ulysses mission made the same observations of the material, and was traced back to a local interstellar cloud.

According to Astronomy, Cassini was able to analyze the material's composition, and it showed that there is a specific mixture of minerals, not just ice. All the grains have a similar chemical makeup, which is a surprise to scientists. It is said to contain major rock-forming elements including magnesium, silicon, iron, and calcium. It also has more reactive elements such as sulfur and carbon, but these were found to be less abundant.

How these dust particles were formed still remains a mystery. Authors of the study found that some types of meteorites have preserved stardust grains, most of which are old, pristine, and compositionally diverse. However, the ones detected by Cassini weren't like that; they were rather uniformed, probably due to some repetitive processing. One possibility includes the dust in a star-forming region being destroyed and recondensed multiple times. Theoretically, they are formed as multiple shockwaves from dying stars were passing through. These then resulted in rather uniform grains like the ones Cassini has observed in our very own solar system.