Subtle movements on the surface of an extraterrestrial world could be evidence of an ocean teeming with life.
Scientists from the California Institute of Technology (Caltech) have revealed that shear movements along unique “tiger stripes” on Saturn’s moon Enceladus may indicate a world filled with life.
The “tiger stripes” consist of four nearly parallel fissures located at the South Pole of Enceladus, first observed by NASA’s Cassini spacecraft in 2005.
Global infrared map of Enceladus taken from different angles, with images from the South Pole clearly showing the massive “tiger stripes” – (Photo: NASA).
“Cryovolcanoes” in this region erupt ice crystals believed to originate from an underground ocean through these fissures, creating large jets that shoot up near the South Pole.
The brightness of these jets and each individual plume appears to vary over Enceladus’s 33-hour rotation around Saturn.
This has led scientists to hypothesize that the activity of these water jets is influenced by tidal forces.
This is encouraging news, as the existence of tides suggests that the subsurface ocean beneath the icy crust of this celestial body may be warmed, as well as possessing the necessary chemical components to sustain life.
However, this theory does not explain why the brightness of Enceladus’s jets peaks several hours after tidal pressure reaches its maximum or why there is a second, slightly smaller, strong eruption shortly after Enceladus makes its closest approach to Saturn.
Caltech’s numerical simulations of tidal stress on Enceladus and the movements of its tiger stripe fissures identify a phenomenon similar to what has been observed at the San Andreas fault in the United States.
The authors discovered that frictional mechanics control the movements along the contact surfaces of Enceladus’s tiger stripes where both sides of the fissure meet.
The correlation between lateral sliding activity and the brightness of the jets in the simulation led the research team to hypothesize that the variability of the jet flow is controlled by the presence of “pull-apart zones” along the fissures.
These are the bent sections of the cracks that open under extensive lateral sliding, allowing water to rise from the subsurface ocean through the icy crust to nourish the cold water jets.
The model also indicates that this lateral sliding is driven by strong tidal forces beneath.
“Understanding the pathways for material transport beneath the surface through the pull-apart zones or fractures is crucial to determining whether the ice particles in Enceladus’s jets represent a potentially habitable global ocean,” said Dr. Alexander Berne, the lead researcher, in an interview with Live Science.
Evidence of the long-term impact of tides on the evolution of Enceladus, which also heats the interior, implies that the ocean on this moon has existed for a long time.
This means that life also has the opportunity to flourish and evolve robustly within this intriguing world.
Of course, to confirm that life exists there 100%, we will need to wait for direct exploration.
Believing in the possibility of life on Enceladus, NASA is developing a snake-like robot, which is expected to venture to this moon in the future, crawling into the fissures to search for evidence of life within the subsurface ocean.
