March 23, 2016
With help from the public, members of NASA’s Cassini mission to Saturn have chosen to call the spacecraft’s ﬁnal orbits the Grand Finale.
In late 2016, the Cassini spacecraft will begin a daring set of orbits that is, in some ways, like a whole new mission. The spacecraft will repeat- edly climb high above Saturn’s poles, ﬂying just outside its narrow F ring. Cassini will probe the water-rich plume of the active geysers on the planet’s intriguing moon Enceladus, and then will hop the rings and dive between the planet and its innermost ring 22 times.
As Cassini plunges past Saturn, the spacecraft will collect some incredibly rich and valuable information that the mission’s original planners might never have imagined. The spacecraft will make detailed maps of Saturn’s gravity and magnetic ﬁelds, revealing how the planet is composed on the inside, and possibly helping to solve the irksome mystery of just how fast the interior is rotating. It will vastly improve our knowledge of how much material is in the rings, bringing us closer to understanding their origins. Cassini’s particle detectors will sample icy ring particles being funneled into the atmosphere by Saturn’s magnetic ﬁeld. And its cameras will take amazing, ultra-close images of Saturn’s rings and clouds.
No other mission has explored this unique re- gion so close to the planet. What we learn from these activities will help to improve our under- standing of how giant planets — and families of planets everywhere — form and evolve. At the end of its ﬁnal orbit, as Cassini falls into Saturn’s atmosphere, it completes its 20-year mission by ensuring that the biologically interesting worlds Enceladus and Titan could never be con- taminated by hardy microbes that might have stowed away and survived the journey intact. It’s inspiring, adventurous and romantic — a ﬁtting end to this thrilling story of discovery.