When Cassini reached Saturn, it fired its rockets for ninety-seven minutes, and used Saturn’s own gravity to slow it down. The spacecraft’s riskiest moments came when it crossed through the plane of Saturn’s rings; the orbital insertion trajectory had been carefully planned so that Cassini would go through the ring plane through a gap, but even one collision with a sizable piece of ring material would have ended the mission. Happily, the orbital insertion was successful. Cassini went on to orbit Saturn in a complex, butterfly-shaped (or “Spirograph”) pattern, zipping in close and then far away from Saturn in highly elliptical loops, in order to gather close-up data about both the planet itself and its fascinating system of rings and moons.