Cassini’s mission around Saturn may have ended almost two years ago, but there are still surprises in the data being analyzed. Researchers have now published an analysis from the closest ever observations of Saturn’s glorious rings.
The rings, named A to G in order of discovery, are a mutable system. They are also young compared to the planet, formed between 10 and 100 million years ago. In the journal Science, the team reports the presence of intricate structures within the rings that range from clumpy to smooth to straw-like.
Some of the patterns are influenced by the shepherd moons that inhabit the rings, but there are also other factors at play. There is evidence of streaks in the F-ring that suggest a group of impactors may have hit the region at the same time. These impactors were likley not asteroids that crossed the path of the planet but material already in orbit around Saturn.
"These new details of how the moons are sculpting the rings in various ways provide a window into solar system formation, where you also have disks evolving under the influence of masses embedded within them," lead author and Cassini scientist Matt Tiscareno, from the SETI Institute in Mountain View, said in a statement.
We don’t know why the ring material is organized in the three different patterns; however, the clumpy, smooth, and streaky patterns are confined to specific belts within the rings.
"This tells us the way the rings look is not just a function of how much material there is," Tiscareno added. "There has to be something different about the characteristics of the particles, perhaps affecting what happens when two ring particles collide and bounce off each other. And we don't yet know what it is."
The main component of the rings is water ice. The new analysis also revealed that organic materials (like those present in ring D), as well as ammonia and methane, are ruled out as possible abundant counterparts to water.
"If organics were there in large amounts – at least in the main A, B and C rings – we'd see them," explained co-author Phil Nicholson, Cassini VIMS scientist from Cornell University. "I'm not convinced yet that they are a major component of the main rings."
This data is providing answers to many questions we have about the rings, but it is also raising more. Cassini was a collaborative mission between NASA, the European Space Agency, and the Italian Space Agency.