NASA has announced that their Cassini spacecraft will begin its final mission before slamming into Saturn on April 23rd. The "final mission" consists of a series of dives through a 1,500-mile-wide gap between Saturn and its rings. "No spacecraft has ever gone through the unique region that we'll attempt to boldly cross 22 times," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "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." The spacecraft will then dive into the gas giant's atmosphere, where it will "break apart, melt, vaporize, and become a part of the very planet it left Earth 20 years ago to explore," Cassini project manager Earl Maize said. Popular Science explains in its report why Cassini has to die: Some space probes are allowed to keep orbiting their targets in perpetuity after their mission ends -- like the Dawn spacecraft at the dwarf planet Ceres. But things are a lot more complicated around Saturn. Whereas Ceres is essentially just a really big rock with no moons, Saturn has 62 satellites, at last count. The gravitational push and pull from those moons -- especially the largest, Titan -- wreak havoc on Cassini's trajectory, which it normally corrects by burning fuel. But the spacecraft's fuel is running out, and ultimately its fate is sealed by its own discoveries; scientists don't want to risk the spacecraft crashing into Titan and Enceladus, which may be capable of supporting life. Although Cassini launched 20 years ago, experiments on the Space Station have suggested microbes can survive for years in the extreme temperatures, radiation, and airless vacuum of space. If NASA were to accidentally put water bears on Enceladus, the tiny Earthlings could potentially wipe out any native lifeforms that the moon may harbor, and/or complicate the search for those alien organisms later. This is why Cassini must die now, while NASA can still control its last swan dive.