NASA’s Cassini mission reveals that Saturn’s rings are young with an ephemeral lifespan

Friday - May 26 2023, 07:11 UTC - 1 year ago

NASA’s Cassini mission data suggests that Saturn’s rings are young, possibly only a few hundred million years old, and could disappear in a similar timescale. Three studies provide evidence to this conclusion, that the rings could not have been exposed to cosmic hailstorm for more than a few hundred million years, and they most likely formed when unstable gravitational forces within Saturn’s system destroyed some of its icy moons. The third study predicts the rings will disappear within the next few hundred million years.

NASA’s Cassini mission data suggests that Saturn’s rings are young, possibly only a few hundred million years old, and could disappear in a similar timescale. The rings’ mass, purity, and debris accumulation rates indicate their relatively young age and short lifespan. Two studies show that the rings formed relatively recently and are rapidly losing mass, while a third predicts their disappearance within the next few hundred million years .

While no human could ever have seen Saturn without its rings, in the time of the dinosaurs, the planet may not yet have acquired its iconic accessories – and future Earth dwellers may again know a world without them.Three recent studies by scientists at NASA’s Ames Research Center in California’s Silicon Valley examine data from NASA’s Cassini mission and provide evidence that Saturn’s rings are both young and ephemeral – in astronomical terms, of course .

The new research looks at the mass of the rings, their "purity," how quickly incoming debris is added, and how that influences the way the rings change over time. Put those elements together, and one can get a better idea of how long they’ve been around and the time they’ve got left.The rings are almost entirely pure ice. Less than a few percent of their mass is non-icy "pollution" coming from micrometeoroids, such as asteroid fragments smaller than a grain of sand .

These constantly collide with the ring particles and contribute debris to the material circling the planet. The rings’ age has been hard to pin down, because scientists hadn’t yet quantified this bombardment in order to calculate how long it must have been going on.Now, one of the three new studies[1] gives a better idea of the total arrival rate of the non-icy material and, thus, how much it should have "contaminated" the rings since their formation .

This research, which was led by the University of Colorado, Boulder, also indicates the micrometeoroids aren’t coming in as fast as scientists thought, which means Saturn’s gravity can pull the material more effectively into the rings. These lines of evidence add up to say the rings could not have been exposed to this cosmic hailstorm for more than a few hundred million years – a small fraction of the 4 .

6-billion-year age of Saturn and the solar system.Backing up this conclusion is the second paper,[2] led by Indiana University, which takes a different angle on the constant battering of the rings by tiny space rocks. The study’s authors identified two things that have been largely neglected in research. Specifically, they were looking at the physics governing the long-term evolution of the rings and found that two important elements are micrometeoroid bombardment and the way debris from those collisions gets distributed within the rings .

Taking these factors into consideration shows the rings could have reached their current mass in just a few hundred million years. The results also suggest that, because they are so young, they most likely formed when unstable gravitational forces within Saturn’s system destroyed some of its icy moons. "The idea that the iconic main rings of Saturn might be a recent feature, made during our own lifetimes, is one which many researchers had predicted would be the case," commented study co-author Professor Matija Ćuk of the SETI Institute .

The third study is from the University of Leicester, and similar to the other two looks at the lifetime of the rings.[3] By looking at the rate of release and injection of matter from the rings, the team was able to predict the rings will disappear relatively soon, within the next few hundred million years.