Cassini-Huygens is a two-part, unmanned spacecraft sent to explore Saturn. NASA's Cassini is a Saturn orbiter, and ESA's Huygens is a lander, for Saturn's moon Titan. The spacecraft launched in 1997 and entered Saturn's orbit in 2004. Huygens separated from Cassini, and landed on Titan in 2005. This was the first landing ever accomplished in the outer Solar System.

Artist's impression of Cassini in orbit
Credit: NASA/JPL

The spacecraft entered the final stage of the mission in 2016, due to its fuel supply running low. Cassini passed very close to Saturn, between the planet's surface and its inner ring, to collect scientific data. On 15th September 2017, Cassini was intentionally destroyed by diving into Saturn's atmosphere. This was to prevent the spacecraft from colliding with and contaminating one of
Saturn's moons.

Cassini has several science goals:

  • to study the structure of Saturn's rings
  • to study the geology of Saturn's moons
  • to investigate the clouds of Saturn's atmosphere
  • to map the surface and cloud patterns of Titan
Cassini photograph of the Great White Spot
Saturn's 'Great White Spot' storm
photographed by Cassini
Credit: NASA/JPL-Caltech
Map of Titan's surface by the Huygens lander
Titan's surface mapped by Huygens
Credit: NASA/JPL


Cassini mapped the locations and sizes of particles in Saturn's rings, and also discovered a storm at Saturn's south pole. In 2012, Cassini witnessed the aftermath of the massive 'Great White Spot' storm, that happens on Saturn every 30 years.

The Huygens lander touched down on the surface of Titan, on solid ground. The lander was designed to survive landing on solid ground or in an ocean. Huygens gathered data for a few hours in Titan's atmosphere, and for 90 minutes once it reached the surface. Photographs from Titan indicate pebbles of water ice scattered over an orange surface, most of which is covered by a thin layer of methane gas.