What were thought to be jets of material erupting from Saturn’s moon Enceladus could be an optical illusion according to researchers with the Planetary Science Institute in Tucson, Arizona.
These jets of water were thought to be signs of a liquid ocean beneath the surface of the icy moon. However, according to the researchers, the images of the jets may be dependent on the angle from which Enceladus is viewed. Instead of jets we may be seeing part of a curtain of of material flowing from fractures in the ice of Saturn’s moon.
“We think most of the observed activity represents curtain eruptions from the ‘tiger stripe’ fractures, rather than intermittent geysers along them. Some prominent jets likely are what they appear to be, but most of the activity seen in the images can be explained without discrete jets,” said Joseph Spitale in a statement.
Spitale is a mission participating scientist with NASA’s Cassini mission, senior scientist at the Planetary Science Institute and lead author of the paper “Curtain eruptions from Enceladus’ south-polar terrain” appearing in the journal Nature on May 7.
The researchers looked at images of the eruptions taken by the Cassini spacecraft and took particular notice of a faint glow, visible in the background of most images. The jets, according to Spitale, appeared to be bright spots superimposed on a consistent background.
The team used computer simulations to model the eruptions as uniform along “tiger stripe fractures” in the surface of Enceladus. They found that the bright patches, described as jets, are visible where the viewers is looking through a “fold” or ripple in the pattern.
The ripples in the pattern are caused by “squiggly” shaped cracks, as opposed to straight ones”. The researchers believe that this is responsible for the optical illusion that caused scientists to see jets.
“The viewing direction plays an important role in where the phantom jets appear. If you rotate your perspective around Enceladus’ south pole, such jets would seem to appear and disappear,” said Spitale.
In the simulated images, the illusory phantom jets line up with features which appear to be columns of spray in the Cassini images.
On Earth, “curtain eruptions” occur when magma gushes out of a deep fracture, rather than a single point. These can be seen in places like Iceland and Hawaii.
This does not necessarily have any implications for the possibility of Enceladus holding life. It is simply a different type of eruption and could actually make it easier for a spacecraft to collect samples of the water from Saturn’s moon.
On Earth there is life everywhere there is water. While this may not necessarily hold true for other parts of the solar system, it will be easier to get a sample from a planet that is actively ejecting water.
The curtains could also be a further sign of hydrothermal activity on the moon. A report from NASA’s Jet Propulsion Laboratory (JPL) in March suggested that materials detected by Cassini could indicate hydrothermal activity. This possibility becomes increasingly interesting in light of two recent studies suggesting that the first life on Earth sprung from the unique environment created by hydrothermal vents and that the first complex cells likely evolved there.
