Nearly 20 years after the start of its mission, NASA's Cassini-Huygens begins the last chapter of its ground-breaking journey, dubbed as the Grand Finale. The legendary spacecraft will end with a bang as it dives down Saturn to crash and burn on the ringed planet on Sept. 15.

But before this fiery goodbye, Cassini will embark on a final set of orbits that include 22 weekly dives in the space between the Saturn and its rings -- an area that has never been explored before, according to NASA. Starting April 22, the journey will take the Cassini from the very inner edge of Saturn's rings to the outer edges of the atmosphere.

The data that will be collected from these multiple flybys are expected to provide valuable knowledge in understanding giant planets and its systems throughout the universe.

Cassini's 20-year mission has been spectacular, a daring exploration of Saturn that has proven to be one of the most successful expeditions in NASA's storied history. From its seven-year journey from Earth to its 13-year orbit around Saturn, Cassini leaves behind a legacy that will be difficult to top with achievements counting the discovery hidden moons and the potential of habitable zones.

"Technologically, it's the most daring and elaborate orbital tour of a planetary system yet executed, with vastly more flybys of planetary bodies, and the closest ever conducted, than any other mission we've ever flown," Cassini Imaging Team head Carolyn Porco said in an interview with Sen.

All good things come to an end, though. According to a report from Mass Live, Cassini is running low on fuel after almost two decades in space. This increases the risk of NASA operators losing control of the spacecraft, which could result in a collision with heavenly objects such as one of Saturn's moons. Since scientists have found potential for life in Titan and Enceladus, it's important to keep these moons from being contaminated.

Instead of risking it, NASA chose to end the Cassini mission with a bold and daring Grand Finale that's worthy of its 20-year service.