More About the Mission :  1997 - 2017  Cassini
After two decades in space, NASA's Cassini spacecraft has ended its remarkable journey of exploration. Having expended almost every bit of the rocket propellant it carried to Saturn, operators deliberately plunged Cassini into the planet to ensure Saturn's moons 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 passed between the planet and its rings. Called the Grand Finale, this final phase of the mission brought unparalleled observations of the planet and its rings from closer than ever before.
On Sept. 15, 2017, the spacecraft made its final approach to the giant planet Saturn. But this encounter was like no other. This time, Cassini dived into the planet's atmosphere, sending science data for as long as its small thrusters could keep the spacecraft's antenna pointed at Earth. Soon after, Cassini burned up and disintegrated like a meteor.
To its very end, Cassini was a mission of thrilling exploration. Launched on Oct. 15, 1997, the mission entered orbit around Saturn on June 30, 2004 (PDT), carrying the European Huygens probe. After its four-year prime mission, Cassini's tour was extended twice. Its key discoveries included the global ocean with indications of hydrothermal activity within Enceladus, and liquid methane seas on Titan.
And although the spacecraft may be gone, its enormous collection of data about Saturn— the giant planet itself, its magnetosphere, rings and moons — will continue to yield new discoveries for decades.
The Grand Finale
In April 2017, NASA's Cassini spacecraft began writing the final, thrilling chapter of its remarkable 20 - year-long story of exploration: its Grand Finale.
Every week, Cassini dived through the approximately 1,200 - mile - wide (2,000 - kilometer - wide) gap between Saturn and its rings. No other spacecraft had ever explored this unique region.
A final close flyby of the moon Titan on April 22 used the moon's gravity to reshape Cassini's trajectory so that the spacecraft leapt over the planet's icy rings to pass between the rings and Saturn. During 22 such passes over about five months, the spacecraft's altitude above Saturn's clouds varied from about 1,000 to 2,500 miles (1,600 to 4,000 kilometers), thanks to occasional distant passes by Titan that shifted the closest approach distance. At times, Cassini skirted the very inner edge of the rings; at other times, it skimmed the outer edges of the atmosphere. During its final five orbits, its orbit passed through Saturn's uppermost atmosphere, before finally plunging directly into the planet on Sept. 15.