Enceladus in 101 Geysers
Two publications have revealed new details about the plumes of material erupting from the southern hemisphere of Enceladus. Scientists have identified 101 geysers on the saturnian moon, and the results indicate that liquid water might be transported from the moon’s subsurface ocean all the way to its surface.
The two papers were published in the Astronomical Journal and together they represent the first comprehensive study of the connections between geysers, tidal stresses, and thermal emissions at the south pole of Enceladus.
In the first study, researchers used 6.5 years of data from NASA’s Cassini spacecraft to identify 101 geysers erupting from the tiny moon. The geysers were found with techniques similar to those used to triangulate geological features on Earth. The results show that geysers are associated with small ‘hot spots’ on the moon – providing clues about the processes behind these eruptions of ice and water vapor.
“There are only two places the materials can originate from,” Carolyn Porco of the Space Science Institute told astrobio.net, “the near-surface, where they would have to be ice melted by friction into liquid and vapor, or the sea. Our work rules out the near-surface.”
Porco is the leader of the Cassini imaging team and lead author of the first paper.
“Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa,” Porco said in a NASA press release. “It also told us the geysers are not a near-surface phenomenon, but have much deeper roots.”
The work also indicates that water contained in Enceladus’ subsurface ocean might remain liquid as it passes up through the icy shell to the surface. Narrow cracks in the ice can remain open all the way from the surface down to the ocean if the cracks are filled with liquid water.
Cracks that reach from the ocean to the surface would not affect the potential for life on Enceladus, but they could provide easy access for sampling the moon’s subsurface ocean. If there is microbial life in the liquid ocean of Enceladus, ice particles from the sea could contain the evidence astrobiologists need to identify them.
“It could be snowing microbes at the surface of Enceladus,” said Porco. “All we have to do is get back there with proper instrumentation to find out.”
The second paper published in the Astronomical Journal shows why the plume brightness and height vary over time as Enceladus circles around Saturn. The giant planet’s powerful gravitational field causes tidal flexing of Enceladus as the moon orbits. This causes the fractures in the its icy crust to open and close, modulating the amount of material being vented by the geysers.