The Cassini spacecraft is about to crash into Saturn. But before that it’s sending back images and information about the planet in more detail than ever seen before.
The spacecraft is currently halfway through the final part of its long journey, which saw it fly all the way to Saturn and then explore it. During its time there it also surveyed its moons – finding information that could indicate that one is supporting life.
When that journey comes to an end, on 15 September, it will dive into Saturn’s atmosphere and get destroyed. That is necessary to keep the craft from infecting any nearby places with life it could be carrying – and will bring Nasa’s mission to a spectacular close.
Cassini’s mission to Saturn Cassini’s mission to Saturn
Before that, however, the ship is still conducting important scientific work that will see it get closer to our ringed neighbour than we ever have before.
Recently, for instance, it has found that Saturn’s magnetic field doesn’t have any particular tilt, meaning we don’t really know how long a day on Saturn is. It has also found out new information about the icy rings that surround the planet, as well as sending back stunning images of its atmosphere.
“Cassini is performing beautifully in the final leg of its long journey,” said Cassini project manager Earl Maize at NASA’s Jet Propulsion Laboratory. “Its observations continue to surprise and delight as we squeeze out every last bit of science that we can get.”
Some of the information that Cassini is finding is actually leading scientists to question what they know, rather than adding to it. “The data we are seeing from Cassini’s Grand Finale are every bit as exciting as we hoped, although we are still deep in the process of working out what they are telling us about Saturn and its rings,” said Cassini project scientist Linda Spilker.
That includes the strange tilting behaviour that scientists have found. It’s thought that being tilted was necessary to actually generate a magnetic field – so that the currents could flow throught the liquid metal that creates them – but Saturn doesn’t seem to have any such tilt.
As well as being strange on its own, that has thrown off plans to measure the wobble of the planet’s interior, and allow scientists to find out exactly how long Saturn’s day lasts. But that’s not possible.
“The tilt seems to be much smaller than we had previously estimated and quite challenging to explain,” said Michele Dougherty, Cassini magnetometer investigation lead at Imperial College, London. “We have not been able to resolve the length of day at Saturn so far, but we’re still working on it.”