April 24 (UPI) -- Cassini said its final goodbye to Titan as it flew by Saturn's largest moon for the final time over the weekend.
The final flyby was the probe's 127th close approach to Titan. On Monday, NASA began fielding images of the encounter, captured by Cassini's radar and imaging cameras and beamed back to Earth.
The radar images revealed a spread of hydrocarbon seas and lakes dotting Titan's north pole.
Scientists plan to use the new data to study the composition of Titan's lakes. They hope their observations will help them explain the moon's "magic island." The brightly colored, pinwheel-shaped island is a transient feature in Titan's Ligeia Mare.
Researchers believe a collection of cresting waves is the most likely explanation for the island, but bubbles or solids on or beneath the surface could also account for the puzzling feature.
"Cassini's up-close exploration of Titan is now behind us, but the rich volume of data the spacecraft has collected will fuel scientific study for decades to come," Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a news release.
Cassini will now begin the final phase of its mission, the "Grand Finale." The finale will feature a planned 22 dives through a 1,500-mile-wide gap between Saturn's atmosphere and its rings.
"No spacecraft has ever gone through the unique region that we'll attempt to boldly cross 22 times," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate in Washington, D.C., said in an update. "What we learn from Cassini's daring final orbits will further our understanding of how giant planets, and planetary systems everywhere, form and evolve. This is truly discovery in action to the very end."
More images and atmospheric samples will be collected and analyzed over the course of 22 intimate orbits. On September 15, Cassini will make one final dive into Saturn's atmosphere.
Though the first of Cassini's 22 dives isn't scheduled until Wednesday, the probe's fate was sealed with its approach of Titan. The intimate flyby slung the probe into a new, high-speed -- and ultimately deadly -- trajectory.
"With this flyby we're committed to the Grand Finale," said Earl Maize, Cassini project manager at JPL. "The spacecraft is now on a ballistic path, so that even if we were to forgo future small course adjustments using thrusters, we would still enter Saturn's atmosphere on Sept. 15 no matter what."