New research helps solve the mystery of so-called “tiger stripes” on Saturn’s moon Enceladus.
Thin fissures covering the planetoid’s south polar region look like a nasty case of “pillow face.” But the wrinkles, first spotted in 2005 by NASA’s Cassini spacecraft, are actually tectonic fractures and ridges that emit jets of water vapor and dust.
“These stripes are like nothing else known in our Solar System,” according to lead study author Doug Hemingway, a postdoctoral fellow at the Carnegie Institution for Science.
Parallel and evenly spaced, the lines measure about 80 miles long and 22 miles apart.
“What makes them especially interesting is that they are continually erupting with water ice, even as we speak,” Hemingway said in a statement. “No other icy planets or moons have anything quite like them.”
Working with Max Rudolph of the University of California, Davis, and Michael Manga from UC Berkeley, Hemingway used models to investigate the physics governing the stripes.
Their findings were published this week in the journal Nature Astronomy.
“We want to know why the eruptions are located at the south pole as opposed to some other place on Enceladus, how these eruptions can be sustained over long periods of time, and finally why these eruptions are emanating from regularly space cracks,” Rudolph, assistant professor at UC Davis, said.
The answer to the first question is less scientific than you’d think: Researchers revealed that the tiger stripe fissures could have formed on either pole—the south just happened to split open first.
Enceladus’s eccentric orbit has left the moon slightly deformed (“stretched and relaxed,” Carnegie Science called it), and the icy satellite’s poles thin with ice. During periods of cooling, the subsurface ocean freezes, causing water to expand and the ice shell to split open, causing a fissure. (Think of it like a can of soda left in the freezer.)
Because of their comparatively thin ice, the poles are most susceptible to cracks. And once the first crack formed, instead of freezing back up (despite a surface temperature of about -328 °F), it stayed open, spewing water.
The weight of ice and snow building up along the edges of the Baghdad fissure (each stripe is named after places referred to in the stories of “The Arabian Nights,” for reasons that remain unknown to me) added pressure to the ice sheet, creating three more parallel crevices.
Tidal effects of Saturn’s gravity repeatedly flush water in and out of the cracks, preventing the wounds from healing and the ice from closing up.
“Since it is thanks to these fissures that we have been able to sample and study Enceladus’ subsurface ocean, which is beloved by astrobiologists, we thought it was important to understand the forces that formed and sustained them,” Hemingway said.
“Our modeling of the physical effects experienced by the moon’s icy shell points to a potentially unique sequence of events and processes that could allow for these distinctive stripes to exist,” he added.
More on Geek.com:
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