The spacecraft that has orbited Saturn for over a decade will soon have its grand finale. Next year Cassini, NASA’s trusty, snuffling space hound, will crash into the planet to avoid contaminating any of Saturn’s potential life-holding moons with Earthly bacteria.
But before the elegant coup de grâce, Cassini will maneuver through the gap between Saturn and its innermost rings to collect once-in-a-lifetime data. Though the end of its life will be bittersweet, here’s what the mission has uncovered:
1. Saturn’s rings are Impressionist beauties.
From afar, they look like smooth, placid hula hoops. But Saturn’s seven rings are actually composed of billions of particles, resembling the technique of short strokes that Impressionist painters relied on to create a larger effect.
2. Ghostly patterns occasionally appear in the rings.
Some grains are microscopic, while others loom as large as the Rocky Mountains.
Astronomers believe them to be shards from comets, asteroids, and other space debris. The rings’ water ice fragments even have complex shapes like bicycle spokes and spiral patterns. Because the spokes disappear quickly, they’re suspected to be lifted above the rings’ surface with an immense electrostatic charge, which NASA likens to holding a staticky balloon above someone’s head.
3. And some of the specks are interstellar!
Cassini munched on dust from Saturn’s rings and analyzed the composition of just 36 grains that stood out. The verdict: Some of the particles are likely to be interstellar, meaning they came from the space between stars, a study published in Science this year suggests. The dust was very uniform in make-up and is suspected to have been destroyed and reformed by cosmic processes, like star-forming, then swept into our system via interstellar winds. Cassini has also sniffed out that Saturn’s moons, like Enceladus, contribute (and sometimes steal) the rings’ icy particles.
4. If the rings extended from Earth, they would almost reach the moon.
Saturn is a gas giant, and other gas planets like Jupiter and Uranus have rings, too. But Saturn’s are so sublime, they span about 282,000 kilometers (about 175,000 miles), which is three-fourths of the distance between Earth and our moon. But the rings are only about a kilometer thick, making them difficult to see from the side.
5. The grand finale will be an unprecedented mission.
Starting November 30th, Cassini will soar above Saturn’s north pole, then dive 22 times between the planet and its inner edge of rings. Each orbit will take almost a week so that it can map Saturn’s gravity and magnetic fields — and beam back up-close-and-personal pictures — in the hopes that we can learn more about how planetary giants evolve. After the last morsels of data trickle in, Cassini will burrow into Saturn’s atmosphere, burying its 20-year career in a final blaze of glory.