From the source:
Since April 2017, NASA's Cassini spacecraft has been writing the final, thrilling chapter of its remarkable 20-year-long story of exploration: its Grand Finale.
Every week, Cassini has been diving through the approximately 1,200-mile-wide (2,000-kilometer-wide) gap between Saturn and its rings. No other spacecraft has ever explored this unique region.
A final close flyby of the moon Titan on April 22 used the moon's gravity to reshape Cassini's trajectory so that the spacecraft leapt over the planet's icy rings to pass between the rings and Saturn. During 22 such passes over about five months, the spacecraft's altitude above Saturn's clouds varied from about 1,000 to 2,500 miles (1,600 to 4,000 kilometers), thanks to occasional distant passes by Titan that shifted the closest approach distance. At times, Cassini skirts the very inner edge of the rings; at other times, it skimmed the outer edges of the atmosphere. During its final five orbits, its orbit passes through Saturn's uppermost atmosphere, before finally plunging directly into the planet on Sept. 15.
Source Cassini: The Grand Finale https://saturn.jpl.nasa.gov/mission/grand-finale/overview/