How Saturn's tiger moon Enceladus got its stripes? It's due to the planet's gravity, say scientists
Thanks to NASA’s Cassini Mission to Saturn, scientists now know that the cracks repeatedly widen and narrow as they dance to the rhythm of Saturn's gravity
The "tiger stripes" on Saturn's icy moon Enceladus — which is roughly the size of England — is an unusual place. The moon's surface, which seals an ocean below, sports four identical cracks called tiger stripes, on the moon's South Pole, a feature that has left scientists both puzzled and excited. Interestingly, scientists can now explain what is driving this unusual tiger stripe appearance in the South Pole.
Thanks to NASA’s Cassini Mission to Saturn, scientists know why the cracks on the surface do not close, despite having a temperature of about negative 200 degrees Celsius. The cracks repeatedly widen and narrow, throwing out the ocean water lying beneath them, as they dance to the rhythm of Saturn's gravity. The study finds that the tidal forces generated by Saturn's gravity ensures that the ice does not close the cracks.
The scientists believe that the ocean water erupting from these cracks could support alien life and future space travel. "Liquid water erupts through the tiger stripes, and that erupted water could be analyzed by future spacecraft," Max Rudolph of the University of California, Davis, told MEA WorldWide (MEAWW).
The tiger stripes sitting on the Moon's icy surface are unlike anything in our solar system, say scientists. "These stripes are parallel and evenly spaced, about 130 km long and 35 km wide. What makes them especially interesting is that they are continually erupting with water ice, even as we speak. No other icy planets or moons have anything quite like them," says Doug Hemingway, lead author from Carnegie Institution for Science.
"Until recently, scientists still did not understand why the stripes are exclusive to the South Pole. So Hemmingway and his colleagues set out to explain this and also figure out why the cracks persist over geologic time," Rudolph told MEAWW.
Making the poles vulnerable to the formation of cracks is Saturn's gravity, says the study. It is this gravity that squeezes the Moon and controls how much ocean water spurts out from them, as revealed by earlier analysis.
According to the analysis from Hemmingway and his colleagues, Enceladus' tiger stripes could have formed on either pole, the south just happened to split open first.
The cracks on the South Pole could be the result of pent-up pressure in the subsurface ocean, below the icy surface, Rudolph told MEAWW. "We think that the first crack formed at the South Pole as a result of forces that build up in the ice shell, which pressurizes the water in the subsurface ocean and pushes the water outwards. When the first crack forms, it allows this pressure in the subsurface ocean to be released," Rudolph said. As water spewing out from the crack falls back as ice, it weighs down the crack a bit. That causes the ice sheet to bend, the researchers calculate, just enough to create a parallel crack about 20 miles away.
The team expects that more cracks might appear on the South Pole, saving the North Pole from such deformations. "Because the pressure is relieved after the formation of the first crack, we do not expect additional cracks to form at the North Pole," Rudolph said.
The study can also help scientists develop a better understanding of other icy bodies in the solar system. "The processes that operate on Enceladus may also operate on other small icy bodies including Jupiter's moon Europa," Rudolph told MEAWW.
The findings are published by Nature Astronomy.