- September 15, 2017 - Planétarium Rio Tinto Alcan : Astronomical News
On September 15, space mission Cassini came to an end in a great fireworks display as the probe disintegrated in the planet Saturn’s atmosphere.
Launched in 1997, the spacecraft entered orbit around the ringed planet in December 2004 after an interplanetary voyage lasting seven years. Thus began an observation mission of Saturn initially planned to last four years, but which would be extended on two occasions.
Huygens and the investigation of Titan
At the start of the mission, a lander named Huygens touched down on Titan, Saturn’s largest moon. To date that’s the most distant object to set down on another world. After a long descent and a soft landing, Huygens revealed to us a strange world with rains, lakes and rivers of methane. The probe’s observations confirmed that Titan strangely resembles early Earth – except that in Titan’s case, water is replaced by ethane and methane.
Icy geysers and hidden ocean
The Cassini mission also helped us better understand the planet Saturn itself, its complex of rings as well as its retinue of natural satellites.
Cassini among other things detected geysers consisting of water ice crystals on the moon Enceladus. Later it even discovered evidence of the presence of an ocean under the surface of that moon.
The probe also tracked an important storm, which lasted almost a year, as well as a hexagon-shaped atmospheric disturbance that still exists at the planet’s north pole. The processes accounting for the formation and persistence of this phenomenon are not yet known.
A glorious grand finale
NASA preferred to destroy the probe in Saturn’s atmosphere, before it ran out of fuel, rather than risk having it crash on the surface of a moon and possibly contaminate the ground with terrestrial microorganisms. That could endanger the chances, however slight they may be, of life developing there one day.
The end of the Cassini mission marks the conclusion to a prodigious chapter of space exploration. In 13 years, the probe completed 293 orbits around Saturn, overflew Titan 127 times and transmitted over 450,000 photographs. Ultimately, Cassini made it possible for us to better understand the formation process of the planets in our solar system. Without question, Cassini was one of the great missions in space history.