Analysis of Planetary Data Confirms Evidence of an Ocean of Liquid Water Beneath Ice Shell of Saturn’s moon Enceladus

A liquid environment where alien life could exist 

Illustration of the interior of Saturn's moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. Thickness of layers shown here is not to scale. Image credit: NASA/JPL-Caltech
Illustration of the interior of Saturn’s moon Enceladus showing a global liquid water ocean between its rocky core and icy crust. The thickness of layers shown here is not to scale. Image credit: NASA/JPL-Caltech

Space news (September 29, 2015) – 30 miles above the icy surface of Saturn’s moon Enceladus – 

NASA planetary scientists and astrophysicists studying seven years of Cassini images and gravitational data provided by the Cassini Solstice Mission believe they have proof positive of the existence of a global liquid ocean of water beneath the icy shell of Saturn’s moon Enceladus. 

NASA's Cassini spacecraft continues to orbit near Saturn. Astrophysicists expect to make even more discoveries in the future.
NASA’s Cassini spacecraft continues to orbit near Saturn. Astrophysicists expect to make even more discoveries in the future. Image credit: JPL/NASA.

By carefully mapping craters and other surface features planetary scientists were able to precisely measure changes in the rotation of Enceladus, which indicated a slight wobble in its orbit. A slight wobble they believe is caused by Enceladus not being perfectly round and traveling faster and slower at different times and positions of its orbit around Saturn. This difference in velocity as it orbits the sixth planet from Sol, causes Saturn to gently rock the moon as it rotates on its axis, producing the slight wobble. 

Planetary scientists found the only way they can account for the magnitude of the very small wobble called a libration- of Enceladus in computer simulations, is if a global ocean of liquid water exists beneath its outer ice shell.

“This was a hard problem that required years of observations, and calculations involving a diverse collection of disciplines, but we are confident we finally got it right,” said Peter Thomas, a Cassini imaging team member at Cornell University, Ithaca, New York, and lead author of the paper.

This is in line with previous data obtained by Cassini and interpreted by planetary scientists as a fine spray of water vapor containing icy particles and basic organic molecules erupting from surface fractures near Enceladus’s southern pole region. Astrophysicists believe the global ocean their analysis indicates exists beneath the ice shell of Enceladus is the source of the fine spray and a possible habitat life could develop and survive in.

“If the surface and core were rigidly connected, the core would provide so much dead weight the wobble would be far smaller than we observe it to be,” said Matthew Tiscareno, a Cassini participating scientist at the SETI Institute, Mountain View, California, and a co-author of the paper. “This proves that there must be a global layer of liquid separating the surface from the core,” he said.

Planetary scientists are currently trying to figure out where the energy keeping the global ocean from completely freezing is coming from. At this point, they think tidal forces due to the gravity of Saturn could be producing a lot more energy than previously calculated. 

“This is a major step beyond what we understood about this moon before, and it demonstrates the kind of deep-dive discoveries we can make with long-lived orbiter missions to other planets,” said co-author Carolyn Porco, Cassini imaging team lead at Space Science Institute (SSI), Boulder, Colorado, and visiting scholar at the University of California, Berkeley. “Cassini has been exemplary in this regard.”

Where’s the heat coming from?

The heat energy keeping the global ocean of Enceladus from freezing could be partly coming from geothermal sources on the bottom of the ocean. Cassini is scheduled to pass over Enceladus again on October 28, 2015, at which time it will only be about 30 miles (49 kilometers) above the surface of the moon, which is the closest the spacecraft will come to the surface. Planetary scientists want to pass through the icy spray, again, to collect more data, and hopefully, determine the reasons the global ocean isn’t frozen.

You can read and learn more about Cassini’s mission to Saturn here.

Go here to discover NASA’s mission to the stars and their future plans.

You can learn more about Saturn’s moon Enceladus here.

Read about a magnetar NASA scientists believe is orbiting the supermassive black hole at the center of the Milky Way, Sagittarius A.

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NASA’s Cassini Spacecraft Identifies 101 Icy Geysers on Saturn’s Moon Enceladus

This graphic shows a 3-D model of 98 geysers whose source locations and tilts were found in a Cassini imaging survey of Enceladus' south polar terrain by the method of triangulation.
This graphic shows a 3-D model of 98 geysers whose source locations and tilts were found in a Cassini imaging survey of Enceladus’ south polar terrain by the method of triangulation.

Analysis of Cassini data identifies 101 distinct icy geysers erupting on surface of Enceladus

Space news – Enceladus, Saturn (Sept 22, 2014) –

Planetary space scientists looking at information obtained by NASA’s Cassini spacecraft of the south polar region of Saturn’s moon Enceladus over a seven-year study have viewed 101 watery-geysers on the surface. This suggests to scientists it’s possible for liquid from the underground sea believed to be under the moon’s icy exterior to reach the surface and erupt as a spray of small, icy particles.

Dramatic plumes, both large and small, spray water ice and vapor from many locations along the famed
Dramatic plumes, both large and small, spray water ice and vapor from many locations along the famed “tiger stripes” near the south pole of Saturn’s moon Enceladus.

NASA’s Cassini spacecraft first saw possible geysers of water vapor erupting from the icy surface of Enceladus almost a decade ago. At this time, tiger stripe fractures could be seen on the surface, and scientists suspected they might have something to do with the geysers they could see. It took until now to confirm, through the seven-year study just completed, the 101 geysers are in fact erupting from the tiger stripe fractures. They also discovered individual geysers originate from small hot spots seen in images collected using Cassini’s temperature-sensing instruments in 2010.

This Cassini narrow-angle camera image -- one of those acquired in the survey conducted by the Cassini imaging science team of the geyser basin at the south pole of Enceladus -- was taken as Cassini was looking across the moon's south pole.
This Cassini narrow-angle camera image — one of those acquired in the survey conducted by the Cassini imaging science team of the geyser basin at the south pole of Enceladus — was taken as Cassini was looking across the moon’s south pole.

“Once we had these results in hand we knew right away heat was not causing the geysers, but vice versa,” said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. “It also told us the geysers are not a near-surface phenomenon but have much deeper roots.”

Next for scientists

Taking a closer look at data concerning the gravity field around Enceladus, planetary space scientists concluded the only plausible source of the liquid erupting from the geysers is the sea beneath the icy exterior of the moon. Computer simulations also show narrow passages to the inner sea could stay open completely to the surface if filled with liquid water.

Additional information on NASA’s Cassini space mission can be found here.

Links to additional information, images and animations can be found here.

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