(Cassini Imaging Team, SSI, JPL, ESA, NASA)
NASA's spacecraft, Cassini, has been orbiting the ringed-planet Saturn for over 10 years, but some of the most interesting discoveries from the mission have come from its occasional visits next door to Saturn's enigmatic moon Enceladus.
In particular, Cassini has revealed evidence Enceladus harbors a vast subsurface ocean beneath an outer, icy crust. And that the floor of this ocean could contain hydrothermal vents, much like the ones on Earth where some evolutionary biologists suspect some of the first life on Earth formed.
Cassini's latest knock on Enceladus' doorstep took place on Oct. 14 when it flew just 1,142 miles above the surface. And while the photos it transmitted back to Earth are still being analyzed, one thing is certain: This is the best-ever view of the moon's north pole we have.
Check it out in the image below:
(NASA/JPL-Caltech/Space Science Institute)
Two features immediately stand out in this spectacular shot: numerous impact craters and giant cracks. The cracks slice into the craters, which means they formed later and therefore are younger.
These cracks are a common feature across the entire surface of Enceladus. They are especially common in the young, smooth regions on the moon, which scientists suspect formed only a few hundreds million years ago. Here's another close-up of those characteristic scars Cassini took on its recent pass:
(NASA/JPL-Caltech/Space Science Institute)
These crack are eerily similar to those on another water-rich moon of Jupiter called Europa. While planetary scientists are still uncertain about what causes these iconic fractures in both of the moons' crust, the leading theory is that warm water under the surface rises through the crust eventually cracking the surface.
When scientists first got a good look at Enceladus' north pole, they were surprised to see the cracks. Earlier, lower-resolution photos of the moon, snapped by Voyager 2, suggested the north pole would be mostly craters, like the ones shown below:
(NASA/JPL-Caltech/Space Science Institute)
But as you can see, these mysterious cracks scar almost every inch of Enceladus, making it a far more complex and enigmatic moon than previously thought. The presence of these cracks on the north pole could suggest some level of subsurface geologic activity.
Cassini has only two more scheduled fly overs of Enceladus — one on Oct. 28 and the final on Dec. 19 of this year. After that, the spacecraft will orbit Saturn until Sept. 2017 when its mission will end. When that happens, NASA scientists will steer the spacecraft into Saturn's atmosphere where it will ultimately be destroyed by pressure.
If there is life on Enceladus, NASA doesn't want to contaminate it with any residual bacteria or other contaminants on the Cassini spacecraft, which is why it will fly to its death in Saturn's beautiful clouds.
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Posted by: hussain almousawi <hussainalmo@yahoo.co.uk>
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