Saturn's rings may not only vanish in 100 million years, but they may have only been around for as little as 10 million years. Using data gathered in the last days of NASA's Cassini mission, a team led by Luciano Iess of Sapienza University of Rome has concluded that the iconic rings may have been created by a disintegrating comet between 10 and 100 million years ago.
Although the rings are synonymous with Saturn today, it appears they could be only a relatively recent addition to the planet. Though Saturn is 4.5 billion years old, the NASA data indicates that they may only be as old as the dinosaurs, or even modern mammals.
According to the space agency, this conclusion was based on remote sensing measurements from both the Voyager flyby missions of 1980 and 1981, and the Cassini spacecraft – with a particular emphasis on the final days of Cassini when it made 22 close approaches to Saturn before burning up in the planet's atmosphere in a controlled entry in 2017.
By monitoring the trajectory of the flybys and the orbiter using NASA's Deep Space Network and ESA's tracking stations, scientists were able to measure the velocity of the spacecraft to within a fraction of a millimeter per second. This allowed them to calculate the gravity of the planet, and therefore also the mass of both the planet and the rings with a high degree of accuracy and create better models of how the rings evolved and are evolving.
What the team found was that the rings have less mass than originally thought and that they are made mostly of ice that is still very clean and bright. This indicates a young age because if they were older, they'd have been darker due to contamination by interplanetary debris.
This younger age gives support to the theory that the rings aren't a remnant of the formation of Saturn, but the break up of a massive comet or icy moon that approached too close to the planet and was torn apart by tidal forces. However, the researchers are currently working on improving their models to have a better understanding of what happened.
The research was published in Science.
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