NASA’s Cassini spacecraft is 18 days from its mission-ending dive into the atmosphere of Saturn. Its fateful plunge on Sept. 15 is a foregone conclusion—an April 22 gravitational kick from Saturn’s moon Titan placed the two-and-a-half ton vehicle on its path for impending destruction. Yet several mission milestones have to occur over the coming two-plus weeks to prepare the vehicle for one last burst of trailblazing science.