On its final mission, threading past hazardous cosmic dust and into hurricanes 1.2bn kilometers away, the Cassini spacecraft will end its 20-year journey with humanity’s closest ever look at what goes on in Saturn’s rings and within its clouds.
On Tuesday, Nasa scientists unveiled their plan for the storied spacecraft, and their reasoning for driving Cassini to its own destruction: with the spacecraft running out of fuel, they do not want to risk it crashing into and contaminating Saturn’s moons, where there may be conditions for alien life.
The tiny moon Enceladus, in particular, has intrigued the researchers. In 2014 and 2015, Cassini found that the frozen moon has an underground saltwater ocean, with geysers spewing plumes high into space, and possibly hydrothermal vents far below the cracked ice. On a flyby, the spacecraft tasted one of those plumes, finding organic chemicals and raising scientists’ hopes that there may be “a brand new paradigm of where bodies may be inhabitable for life”, said Jim Green, director of Nasa’s planetary science division.
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