13 years orbiting Saturn — the most successful outer-planet mission
Cassini spent 13 years orbiting Saturn, executing 293 orbits and returning over 450,000 images. It carried the Huygens probe, which landed on Titan in 2005 — the most distant landing ever achieved. Cassini discovered active geysers on Enceladus and confirmed a subsurface liquid water ocean, making it one of the most promising candidates for extraterrestrial life. On September 15, 2017, with fuel nearly exhausted, Cassini was deliberately plunged into Saturn's atmosphere in the "Grand Finale" to protect potentially habitable moons from contamination.