It is difficult to imagine the planet Saturn without its charismatic rings. But it hasn’t always had them, and it won’t always have them. Three recent studies have explored various questions about the formation of these rings and their future.
Saturn’s rings are almost entirely pure ice. Only a tiny percentage of its mass corresponds to “impurities”, coming from micrometeoroids, such as fragments smaller than a grain of sand detached from asteroids. These particles constantly collide with those of the ring and add extra material to the one that already surrounds the planet. In any case, the rings also undergo processes that cause a loss of material.
The age of the rings has been difficult to pin down, because scientists had not yet quantified this bombardment of extra material to calculate how long it must have been going on.
Now, one of the three new studies provides a clearer and more reliable estimate of the overall rate of arrival of non-ice material, and thus how much this material must have “contaminated” the rings since their formation. This research has been carried out by an international team made up of, among others, Sascha Kempf, from the University of Colorado at Boulder, United States, and Nicolas Altobelli, from the ESA (European Space Agency) European Center for Space Astronomy in Spain.
This study also shows that the arrival rate of micrometeoroids in the rings is lower than previously thought, meaning that Saturn’s gravity pulls material toward the rings more efficiently than previously thought. All of this supports the suspicion that Saturn’s rings are only a few hundred million years old, a small fraction of the 4.6 billion-year age of Saturn and the solar system.
Saturn with its rings, in an image made from photos taken by the Cassini space probe on January 2, 2010. The photos were taken from approximately 2.3 million kilometers away from Saturn. (Image: NASA JPL/Caltech/Space Science Institute)
The second of the studies, carried out by Paul R. Estrada of NASA and Richard H. Durisen of Indiana University, both institutions in the United States, also gives that approximate age as a result. Taking into account factors not accounted for in previous studies, this new research determines that it took a few hundred million years for Saturn’s rings to reach the approximate mass they now have.
As for how much longer Saturn’s rings will last, the third study, also by Estrada and Durisen, takes into account the rate at which the rings are losing mass and concludes that the rings will gradually dissipate and that in a few hundred million years they will no longer exist.
As Estrada reasons, the ephemeral nature of Saturn’s rings suggests that the present almost imperceptible rings of Uranus and Neptune were perhaps as showy in the past as those Saturn has today, and that the process that will eliminate these has already done so. almost completely that work in those of Uranus and Neptune.
The first study is entitled “Micrometeoroid infall onto Saturn’s rings constraints their age to no more than a few hundred million years”. And it has been published in the academic journal Science Advances. The second is entitled “Constraints on the initial mass, age and lifetime of Saturn’s rings from viscous evolutions that include pollution and transport due to micrometeoroid bombardment”. And it has been published in the academic journal Icarus. The third is entitled “Large mass inflow rates in Saturn’s rings due to ballistic transport and mass loading”. And it has also been published in Icarus. (Fountain: NCYT de Amazings)
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