US spacecraft to dive into Saturn's rings in 'grand finale'

12 years of Saturn research come to an end as scientists wait for the last few questions to be answered.

Contact Editor
Chana Roberts,

Saturn
Saturn
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NASA's Cassini spacecraft on Saturday soared past Titan for the last time, using its gravitational pull to slingshot into a series of exploratory dives in the planet's rings.

Titan is Saturn's largest moon, and its northern latitudes are dominated by lakes and seas made of methane. Often, nitrogen gas bubbles up from below the seas' surface, producing a transient bumpiness on the seas' surfaces.

On another moon, Enceladus, the oceans contain all the necessary requirements for life to thrive.

When Cassini is finished exploring Saturn's rings, it will dive into the planet itself, in a "grand finale."

Cassini is expected to make the first of 22 exploratory dives on Wednesday. These dives will take it in between Saturn's rings, in an attempt to determine their age and to determine the length of a single day on Saturn.

Cassini has been traveling in space for nearly twenty years, 12 of them at Saturn. The craft's propellant tanks are nearly empty, and it will self-destruct in its last dive on September 15, when it dives directly into Saturn's atmosphere.

NASA controllers say the decision to have Cassini self-destruct was made because it would otherwise risk crashing into, and contaminating, Saturn's potentially life-supporting moons.

"If Cassini runs out of fuel it would be uncontrolled and the possibility that it could crash-land on the moons of Titan and/or Enceladus are unacceptably high," said Dr Earl Maize, Nasa's Cassini program manager.

"We could put it into a very long orbit far from Saturn but the science return from that would be nowhere near as good as what we're about to do," he told BBC News.

Saturn is the second-largest planet in the Solar System after Jupiter and has 62 confirmed or potential moons.








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