We are getting ready to say goodbye to NASA’s incredible Cassini spacecraft, which has been orbiting the gas giant of Saturn for the last 13 years, teaching us all sorts of amazing details not only about this planet, but the solar system and even the universe itself. Now, NASA is getting ready to end a journey that began 20 years ago with “The Grand Finale,” as the agency gets set to send Cassini plunging to her death into the heart of Saturn.

Cassini is running low on fuel, so mission operators will soon not be able to control the spacecraft. As a result, they’re sending Cassini on a final mission that will send the $3.26 billion spacecraft through the planet’s famous rings and then into the planet itself on Sept. 15.

Cassini will continue to collect information and send it back to Earth right up until the very end. It will certainly go down as one of the most successful NASA missions in history, and its presence in the solar system will certainly be missed.

“After two decades in space, NASA’s Cassini spacecraft is nearing the end of its remarkable journey of exploration,” NASA says on their website. “Having expended almost every bit of the rocket propellant it carried to Saturn, operators are deliberately plunging Cassini into the planet to ensure Saturn’s moons will remain pristine for future exploration—in particular, the ice-covered, ocean-bearing moon Enceladus, but also Titan, with its intriguing pre-biotic chemistry.

“Beginning in 2010, Cassini began a seven-year mission extension in which it completed many moon flybys while observing seasonal changes on Saturn and Titan. The plan for this phase of the mission was to expend all of the spacecraft’s propellant while exploring Saturn, ending with a plunge into the planet’s atmosphere. In April 2017, Cassini was placed on an impact course that unfolded over five months of daring dives—a series of 22 orbits that each pass between the planet and its rings. Called the Grand Finale, this final phase of the mission has brought unparalleled observations of the planet and its rings from closer than ever before.”