NASA has published an image of the north polar region of Enceladus taken by the Cassini-Huygens spacecraft. The region is less active than the south polar region:
A recently released photo by NASA's Saturn-orbiting Cassini spacecraft shows the many craters, as well as snaking fissures and other geological features, pocking the northern reaches of 313-mile-wide (504 kilometers) Enceladus.
The presence of so many craters indicates that the region hasn't been resurfaced in a long time. However, it's a totally different story near Enceladus' south pole, which "shows signs of intense geologic activity, most prominently focused around the long fractures known as 'tiger stripes' that spray gas and tiny particles from the moon," NASA officials wrote in an image description on May 3.
This geological activity is driven primarily by Saturn's powerful gravitational pull, which churns and stretches Enceladus' interior, generating lots of friction and heat. This heat keeps the moon's subsurface ocean of liquid water from freezing, and also drives the geysers that blast from the tiger stripes, scientists have said.
Cassini has finished a fifth trip between Saturn and its rings, and will make another pass next week.
Also at The Space Reporter. See also: Expecting the Unexpected on Saturn's Moons.
(Score: 2) by kaszz on Thursday May 25 2017, @12:59AM (3 children)
How can the atmosphere have a composition by volume with 91% water vapor and a temperature maximum of −128 °C ?
Not even considering how damp that would be.
(Score: 3, Informative) by bob_super on Thursday May 25 2017, @01:10AM (2 children)
By having a pressure that's extremely low:
https://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Phase_diagram_of_water.svg/725px-Phase_diagram_of_water.svg.png [wikimedia.org]
(Score: 0) by Anonymous Coward on Thursday May 25 2017, @10:34AM (1 child)
Your diagram cuts of at 10uPa, but if we extrapolate the edges of phase zones, for -128 degrees centigrade, to get water vapor the pressure should be in pico- or even nano- bars
(Score: 2) by kaszz on Thursday May 25 2017, @12:04PM
Actually the diagram cuts of at 1 Pa ..
But the shape of the vapor phase seems like it's possible to model using formulas and thus calculate the values for -128 ⁰C and lower.