14 DAY TRIAL // The geysers on the Saturn's moon Enceladus are one of the most spectacular shows in our solar system. In 2006, NASA's Cassini spacecraft discovered in 2006 plumes of icy water vapors that kept intriguing astronomers ever since.
Early theories suggested the geysers could be generated by liquid water under the surface of the satellite that instantly freezes when hurled into space. This led to speculations about the existence of lifeforms in an underground layer of liquid water.
New discoveries on the subject have put this theory on ice, as it is now certain that the geysers are caused by the friction between massive plates of ice, tens of kilometers deep that keep grinding together at fault lines. It's actually the heat caused by this friction that turns the ice directly into vapor, thus producing the gases.
"The two sides are rubbing backwards and forwards against each other," said Francis Nimmo, a planetary scientist at the University of California, Santa Cruz, and lead author of one study. "Just like when you rub your hands together, you get heat-that is how we think the ice is being heated up."
It is believed that Saturn's gravitational pull is making the ice plates move around, similar to tides on Earth caused by the Moon and the Sun.
"Enceladus's orbit isn't quite circular," Nimmo said. "As it goes around Saturn the distance between them is changing, so Saturn's gravitational attraction is changing."
However, the astronomers didn't completely remove the possibility of a layer of liquid water existing somewhere beneath the surface of Enceladus, but they think at best, it's buried deep under the outer layers, so the possibility of reaching it with a probe will be extremely remote.
"We suggest that you need to have an ocean somewhere down there," Nimmo explained. "If you didn't, the ice shell would be stuck to the rigid rock interior [and would not move]. If there is an ocean below and the ice shell is floating, it could move to produce the friction and heating."