After 13 years of exciting discoveries, NASA's Cassini spacecraft is making its final orbits of Saturn. On September 15 it will commence its mission-ending plunge into the thick atmosphere of the gas giant, but recent observations are proving that Cassini still has some surprises in store.
Dubbed the "Grand Finale", this conclusive phase of Cassini's mission involves 22 dives through the 1,500-mile-wide (2,400-km) gap between the planet and its rings. Since it began these final dives back in April it has sent back several stunning views of Saturn's rings, including a compelling insight into "the big empty", a fascinating expanse of space between the rings and the planet.
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One of the biggest new mysteries of Saturn revealed by Cassini in these final dives is that the planet's magnetic field has no discernible tilt, with data suggesting that it is surprisingly well-aligned with the planet's rotation axis. Scientists are currently perplexed at this observation, as it is generally understood that some degree of tilt is necessary for a planet to sustain its magnetic field.
"The tilt seems to be much smaller than we had previously estimated and quite challenging to explain," says Michele Dougherty, Cassini magnetometer investigation lead at Imperial College, London.
Cassini also recently gathered samples of the planet's outer atmosphere during one of its close orbital dives. As it takes its final plunges over the coming weeks the craft is set to gather data from deeper down in the planet's atmosphere, which will provide new insights into Saturn's composition.
As well as a treasure trove of new data, this "Grand Finale" plunge is delivering a torrent of new images. Most recently NASA published what it calls a "Ring-Bow" (seen below), highlighting Saturn's rings from a perspective never seen before.
"Cassini is performing beautifully in the final leg of its long journey," says Cassini Project Manager Earl Maize at NASA's Jet Propulsion Laboratory, Pasadena, California. "Its observations continue to surprise and delight as we squeeze out every last bit of science that we can get."
Take a look through our spectacular gallery of majestic Saturn images that Cassini has captured over the past decade.
Source: NASAView gallery - 42 images