The E-ring is quite unlike all the other rings of Saturn. It is much wider, roughly the Earth-Moon distance, and much thicker than the other rings. It is also rich in microscopic particles of ice and silica and the Cassini mission identified the icy moon Enceladus as its creator.
Underneath its icy shell, Enceladus harbors a deep water-ocean with hydrothermal activity at its bottom. And on the southern pole of the moon, a region called the tiger stripes is known to have geysers. And these geysers launch material into space and ended up forming the E-ring.
It is unclear how the nano-silica particles seen by Cassini formed but one suggestion sees them as coming from the seafloor of Enceladus, and new models agree with the idea. Materials can be lifted from the moon’s seafloor and taken to the icy shell in a matter of months.
“Our model shows that these grains may be transported through the ocean interior on timescales faster than previously thought,” Assistant Professor Emily Hawkins, from Loyola Marymount University, said in a statement. “The nano-silica material is thought to be important in the generation of life on the icy moon. Ultimately, our research aids in the understanding of the habitability of Enceladus, and will guide future missions to the outer solar system moon.”
What keeps the interior of Enceladus going is the tidal forces it experiences as it goes around Saturn in a strongly elliptical orbit. The forces squish the rocky core and the ice shell and the bottom of the ocean gets heated by hydrothermal vents that form there.
“It’s like boiling a pot on a stove. Tidal friction adds heat to the ocean and causes upwelling currents of warm water,” explained planetary scientist Ashley Schoenfeld, the article’s lead author and a graduate student at the University of California, Los Angeles. “What our study shows is that these flows are strong enough to pick up materials from the seafloor and bring them to the ice shell that separates the ocean from the vacuum of space.”
While it takes only a few months for particles to rise from the seafloor, it is unclear how long its takes for them to be sprayed into space. The process might be quick or it could involve more complex processes related to the ice shell.
The team is now looking further into this distant ocean evolution and investigating what might end up in space. But it is clear that understanding the composition of the E-rings might provide fantastic insights into what lies beneath the ice shelf. Maybe even life.
The work was published in Communications Earth & Environment.