When Cassini makes its final, fiery crash into Saturn, that's the moment our eye on the planet and its moons will close, and who knows when another will open.
"Cassini has been in a long-term relationship with Titan, with a new rendezvous almost every month for more than a decade". It astonished scientists by finding conditions potentially suitable for life beneath the surface of one of Saturn's icy moons, Enceladus.
There's little chance telescopes will see the 20-year, $3.26-billion mission come to an end.
The dive that Cassini is now performing is the very last part of its Grand Finale which included 22 spectacular dives through Saturn's iconic rings.
As Cassini approaches Saturn, it will continue taking photos of the planet, its rings and moons, with its final images expected to be received Thursday night. This is another reason the mission scientists decided on Cassini's particular end-game.
"In 2010, NASA made a decision to end the mission with a purposeful plunge into Saturn this year in order to protect and preserve the planet's moons for future exploration - especially the potentially habitable Enceladus", the statement read.
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You can track the current position of Cassini, relative to Saturn, on NASA's live-updating tracker.
The European Space Agency's Huygens lander - which hitchhiked all the way to Saturn aboard Cassini - still rests on Titan. When Cassini arrived, the northern hemisphere of Saturn was emerging from winter.
While discovery was Cassini-Huygens' job, scientists played a critical role in utilizing the data produced by the satellite.
Cassini changed the way scientists understood the Saturn system and raised new questions: Could there be a liquid water. The National Aeronautics and Space Administration in a statement released in April said that Cassini is running low on fuel.
Future engineers will borrow that trick to explore Jupiter's moon Europa with the Clipper mission, which is planned to launch in the 2020s.
Intrigued by Cassini's discoveries, scientists have submitted concepts for future "spacecraft to drift on the methane seas of Titan and fly through the Enceladus plume to collect and analyze samples for signs of biology" that are now under consideration, according to NASA.