Cassini Spacecraft Bathed in Ring Rain in its Final Orbits Around Saturn

NASA’s Cassini mission came to an end in September 2017, but it continues to make exciting discoveries about Saturn and its amazing ring system.

In its final days, Cassini spacecraft dove through the narrow gap between Saturn and its rings multiple times. a space less than 1,200 miles wide. No spacecraft had gone through this unique region before. Data from those final orbits of Cassini shows that the spacecraft experienced a downpour of dust that astronomers call “ring rain.”

“Our measurements show what exactly these materials are, how they are distributed and how much dust is coming into Saturn.” Lead author Hsiang-Wen (Sean) Hsu from CU Boulder said.

Cassini spacecraft made an unprecedented series of weekly dives between Saturn and its rings as part of the mission’s grand finale. The grand finale began on April 26 and continued until Sept. 15, when the spacecraft made a final plunge and burned up in Saturn’s atmosphere.

The grand finale consisted of 22 orbits between Saturn and its rings. During eight of those final orbits, Cassini’s Cosmic Dust Analyzer instrument captured more than 2,700 charged bits of dust or ring rain. That’s equivalent to sending about one metric ton of material into Saturn’s atmosphere every second.

Based on data collected by Cassini instruments, researchers concluded that the particles were made of bits of water ice, the main component of Saturn’s rings. Furthermore, the spacecraft picked up a lot of tiny silicates that create many space rocks.

“This is the first time that pieces from Saturn’s rings have been analyzed with a human-made instrument,” said Sascha Kempf, co-author of the study from Laboratory for Atmospheric and Space Physics (LASP). “If you had asked us years ago if this was even possible, we would have told you ‘no way.’”

Although particles throughout the rings ranged from large to small particles, the cosmic dust analyzer mostly collected microscopic material. The findings suggest that some unknown process is grinding up particles in the Saturn’s gap.

“For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere,” NASA statement said. “Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes — a phenomenon known as “ring rain.” But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it’s all falling out of the rings faster than scientists thought — as much as 22,000 pounds (10,000 kilograms) of material per second.”