Saturn Cassini Spacecraft Studies Interstellar Dust From Beyond The Solar System

Studying interstellar dust beyond our solar system, a Heidelberg-designed dust detector on the Cassini space probe has located a number of rare and minuscule particles.

Particles of the interstellar dust reaching our solar system are being examined by the Stardust space probe, which captures particles of the weak flux. Still, being very large, such findings are not really representative of dust in outer space.

"Interstellar dust is one of the last bastions of the unknown in space, its individual particles being only about 200 nanometers in size and very hard to find," said Mario Trieloff, earth scientist from Heidelberg University.

The Cassini probe could locate 36 particles of interstellar dust among millions of particles. They were analyzed on the spot with mass spectrometry, which yielded more precise results.

"The result of the measurements was truly amazing," said  Frank Postberg, one of the researchers. "The 36 particles of interstellar origin, that are very similar in their composition, contain a mix of the most important rock-forming elements---magnesium, iron, silicon and calcium-in average cosmic abundance. Although a dust particle has a mass of less than a trillionth of a gram, the whole element mix of the cosmos is collected there, with the exception of very volatile gases. Some particles cannot be found in our solar system."

The dust had got homogenized in the cosmic, interstellar medium, with its million-degree hot bubbles of supernova explosions. Their edges arose from shock fronts expanding into the universe. The interstellar dust can survive the energy-rich environment for just a few hundred million years.

Most of the particles get destroyed and reformed in molecular clouds, which are then brought as homogenized dust into the solar system. However, they tell us little about faraway clouds.

The findings were published on April 15, 2016, issue of the journal Science.