Enormous 'San Andreas fault' on Saturn's moon could help reveal signs of alien life

New research has revealed the sliding side-by-side motion along distinctive "tiger stripes" on Saturn's moon Enceladus is linked to jets of ice crystals that erupt from its icy shell. The findings could help determine the characteristics of this icy moon of Saturn's subsurface ocean and, thus, if Enceladus is favorable to life.

The tiger stripes of Enceladus consist of four parallel line fractures in the moon's south pole that were first observed by NASA's Cassini spacecraft in 2005. "Cryovolcanism" in this region blasts out ice crystals believed to originate from Enceladus' buried ocean from these fractures, causing a broad plume of material to gather over the south pole of the Saturnian moon.

Both the brightness of this plume and the jets that create it seem to vary in a pattern that lines up with the near 33-hour orbit of Enceladus around Saturn, the solar system's second most massive planet. This has led scientists to theorize that the activity of the jets increases as tidal stress acts upon the tiger stripes. 

However, this theory can't explain why the jets of Enceladus peak in brightness hours after tidal stresses are at their maximum or why there is a second smaller peak seen shortly after Enceladus' closest approach to Saturn. A new numerical simulation of Enceladus' tidal stresses and the motion of its tiger stripe fractures identifies a phenomenon similar to that seen at the San Andreas fault, corresponding with the pattern of jet activity.  

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"We developed a sophisticated numerical model to simulate tidally-driven strike-slip motion along Enceladus' faults. These models consider the role of friction, which causes the amount of slip on the faults to be sensitive to both compressional and shearing stresses," Alexander Berne, leader of the team behind the simulation and a PhD Candidate at the California Institute of Technology (Caltech), told Space.com. 

"The numerical model was able to simulate slip along Enceladus's faults in a manner which matched observed variations in plume brightness as well as spatial variations in surface temperature, suggesting that the jets and plume brightness variations are controlled by strike-slip motion over Enceladus' orbit."