Space & Innovation

Enceladus Spreads Ghostly Ice Tendrils Around Saturn

A ghostly apparition has long been known to follow Saturn moon Enceladus in its orbit around the gas giant. But until now, scientists have had a hard time tracking its source.

A ghostly apparition has long been known to follow Saturn moon Enceladus in its orbit around the gas giant. But until now, scientists have had a hard time tracking its source.

Using images from NASA's Cassini mission, the source of these tendrils have been tracked down and they originate from the icy moon's famous geysers. But even better than that, scientists have been able to track the specific tendril shapes down to the specific geysers that produce them.

PHOTOS: Enceladus: Saturn's Snowball Ocean Moon

"We've been able to show that each unique tendril structure can be reproduced by particular sets of geysers on the moon's surface," said Colin Mitchell, a Cassini imaging team associate at the Space Science Institute in Boulder, Colo., and lead author of a paper published int he Astrophysical Journal.

Mitchell's team combined the high-resolution Cassini data with computer simulations to track the trajectories of the ice grains to individual geysers blasting through giant fissures in Enceladus' icy crust. Consisting of tiny ice particles, dust and organic molecules, the geysers provide a tantalizing view into the components of the sub-surface ocean that is theorized to exist below the moon's thick icy crust.

From Enceladus, these huge features reach tens of thousands of miles away into Saturn's E ring, supplying it with icy particles. The researchers were able to deduce the size of the ice particles in the E-ring and the tendrils, measuring them to "no smaller than about a hundred thousandth of an inch," according to a NASA news release. This provided a direct link from Enceladus' geysers to one of Saturn's outer rings.

ANALYSIS: Enceladus Has Potentially Life-Giving Hydrothermal Activity

Throughout Cassini's studies of Enceladus' tendrils, variations in their shape and size have become apparent, probably due to the tidal squeezing regulating the icy output from the moon's contracting and expanding fissures. Further work is needed to verify this correlation, however.

A cool implication of this work is that understanding the dynamics of Enceladus' tendrils may provide an accurate measure on how ice is leaving the small moon and how much is making it to the E ring. This, in turn, may help planetary scientists understand the lifetime and evolution of Enceladus' sub-surface ocean.

"As the supply lanes for Saturn's E ring, the tendrils give us a way to ascertain how much mass is leaving Enceladus and making its way into Saturn orbit," said Carolyn Porco, team leader for the imaging experiment and a coauthor on the paper. "So, another important step is to determine how much mass is involved, and thus estimate how much longer the moon's sub-surface ocean may last."

ANALYSIS: Saturn's Moon Enceladus Has Underground Ocean

As Cassini's mission is drawing to a close, Enceladus is being singled out as an important target for the spacecraft to continue to study. Along with a growing number of outer solar system moons, the nature of Enceladus and its ocean raises key questions about the possibility of life beyond Earth, so further studies of these ghostly tendrils and the moon's extensive array of geysers are planned.

Source: NASA/JPL-Caltech

A Cassini observation of Enceladus' icy tendrils (left) and a computer simulation of the tendrils that are known to feed Saturn's E ring with material.

On April 3, planetary scientists announced the discovery of a subsurface ocean (at least as big as Lake Superior) sitting on top of Enceladus' rocky core at a depth of about 31 miles. The discovery was made by NASA's Cassini spacecraft that buzzed the 300 mile-wide Saturnian moon on three occasions between 2010 and 2012. This is the first strong evidence of the existence of a sub-surface liquid body of water, but ever since Cassini observed the active moon's water ice plumes, scientists have speculated about their source.

A "snowball" moon: Enceladus is bathed in light in this view from Cassini -- its icy surface exhibits huge cracks, a sure sign of an internal heat source that drives the little moon's famous geysers.

Enceladus' famous plumes are known to be composed of salty water vapor laced with organic compounds, an indication that a sub-surface liquid water reservoir is being heated and blasted through cracks in the moon's icy crust.

A mosaic of the global map of Enceladus, created using images taken during Cassini spacecraft flybys.

In 2012, Cassini captured this view of Enceladus in front of Saturn's rings and bigger moon sibling Titan in the background.

The nightside of Enceladus and backlit plumes of water ice.

A close-up of Enceladus' cracked icy terrain as observed by Cassini. The relative sparsity of impact craters is an indicator of how 'young' the moon's crust is -- ice is continuously cycled with new layers being replaced by tectonic activity.

This 2010 observation by Cassini shows the new and old surface of Enceladus -- a newly created terrain in the upper right meets older, cratered terrain in the lower left.

Small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus in this image taken during the Aug. 13, 2010, flyby of the moon by NASA's Cassini spacecraft.

This sweeping mosaic of Saturn's moon Enceladus provides broad regional context for the ultra-sharp, close-up views NASA's Cassini spacecraft acquired minutes earlier, during its flyby on Aug. 11, 2008.

A heat map of Enceladus' famous "tiger stripes" -- long fissures etched into the moon's south pole where subsurface water is released as water vapor that quickly freezes to create plumes of water ice particles.

A high-resolution view of Enceladus' vast "tiger stripes" etched into the moon's south pole as observed by the Cassini mission.

For more stunning imagery of Enceladus, browse the Cassini Imaging Central Laboratory for Operations (CICLOPS) webpages.