We Finally Know How Saturn's Moon Enceladus Earned Those 'Tiger Stripes' on Its South Pole

Monday, 09 December 2019 - 5:07PM
Space
Monday, 09 December 2019 - 5:07PM
We Finally Know How Saturn's Moon Enceladus Earned Those 'Tiger Stripes' on Its South Pole
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NASA/JPL/Space Science Institute

The south pole of Enceladus – one of Saturn's moons – is strangely unmarked by impact craters from passing meteors and asteroids, with a bizarre field of equally-spaced "tiger stripes" running across the pole. Scientists have puzzled over these stripes for decades and new research promises to reveal the answer, according to new reports from Astronomy Magazine.


"People have been interested in this ever since that was discovered, and it's been in kind of the back of everyone's mind," said Douglas Hemingway, one of the study's authors and a planetary scientist at the Carnegie Institution for Science. "What exactly are these things? Why do they form?"


Enceladus is Saturn's sixth-largest moon with a diameter of about 310 miles. Its smooth icy surface is paper-white and extremely reflective – the most reflective object in the entire solar system.


NASA's Voyagers 1 and 2 probes sent back the first images of Enceladus in the 1980s, but it wasn't until the Cassini mission that we got a truly detailed look at the moon. Cassini revealed most of what we know about Enceladus today: things like a giant saltwater ocean beneath its icy crust, and plumes of ice water jets shooting into space at speeds of up to 800 miles per hour.


Previous research suggested that, as the water from these jets froze and accumulated on the surface, the ensuing pressure would force the moon's crust to fracture. It makes sense ­– at first. Enceladus' ice is thinnest at the north and south poles, so they're a likely point of fracture. But why are these fissures running in straight lines so evenly spaced apart?


Hemingway and his team expanded on the existing theory, hypothesizing that, once the first crack formed and the ice shell bent, that would exert enough pressure over time for the ice to crack again – and again, and again – thus creating those stripes. But why the calculated spacing?


The ice must bend at very specific intervals that are determined by the physical properties of its chemical composition. They ran the math – it corresponds perfectly with the calculations for Enceladus' ice.


A research paper was published on Monday in the peer-reviewed journal Nature.



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