Huygens probe
esa-built atmospheric and surface probe carried to Saturn by the Cassini orbiter. Separated from Cassini December 25, 2004; descended through titan’s atmosphere on January 14, 2005 for approximately 2.5 hours and returned data from Titan’s surface for an additional ~72 minutes. Remains the most distant landing humanity has ever pulled off. (src-cassini-huygens-ocean-worlds-2026-04)
The probe delivered the first direct measurements of Titan’s lower atmospheric chemistry, surface composition, and weather, converting prior theoretical models of methane/ethane hydrology into observed geology. Huygens’s results were the empirical foundation that made nasa’s dragonfly-mission (a Titan rotorcraft scheduled for the 2030s) possible as a funded program.