An artist’s impression of the Cassini spacecraft during its final orbits, repeatedly passing between Saturn’s rings and its cloud tops. Data collected during those orbits show the rings are a relatively recent phenomenon. Image: NASA/JPL-Caltech
More than a year after NASA’s Cassini spacecraft ended its hugely successful mission with a suicidal plunge into Saturn’s atmosphere, researchers have analysed data collected during its final orbits to determine the mass of the planet’s spectacular ring system and in so doing, its age.
Some researchers theorised the rings formed along with the planet some 4.5 billion years ago while others thought they must be a relatively recent phenomenon, the result of a Kuiper Belt body that wandered too close and was ripped apart by Saturn’s gravity.
The Cassini data indicate the latter case is the most probable. The material making up the rings represents about 40 percent the mass of Saturn’s moon Mimas, a diminutive body 2,000 times smaller than Earth’s Moon, and that, in turn, indicates the rings likely formed between 10 million and 100 million years ago.
“Only by getting so close to Saturn in Cassini’s final orbits were we able to gather the measurements to make the new discoveries,” said ...