Death Star Moon may be 'Wonky or Watery'

A team of astronomers from the EU and US have come to the conclusion the Saturn's Moon Mimas either has a core shaped like a rugby ball or it has a liquid ocean between the core and the surface , the conclusion comes as an answer to the mystery of why Mimas wobbles so much in its orbit.

The researchers built a detailed 3D model of Mimas using images taken from various angles, and tracked the movement of hundreds of reference points on its pockmarked surface. "After carefully examining Mimas, we found it librates - that is, it subtly wobbles - around the moon's polar axis," said lead author Dr Radwan Tajeddine, who works at Cornell University in the US. Apart from these gentle "librations", Mimas otherwise presents the same face to Saturn throughout its orbit.

Mimas.

Sorry ... Mimas

Firstly, their calculations suggested that the wobbles could arise from a core that was squashed or elongated by 20-60km: a huge, central rugby ball of rock.
Alternatively, the moon could have a normal spherical core and crust, but separated by a "global ocean". That way, Dr Tajeddine explained, "the shell can wobble more easily, because it's not attached to another mass".
Of the two explanations, he favours the subterranean sea. "When we saw this wobbling, the first thing we thought of was an ocean," Dr Tajeddine said.
www.bbc.co.uk...

Water water everywhere but no life to live in it ? .... I don't think so.

originally posted by: gortex

Water water everywhere but no life to live in it ? .... I don't think so.

Right Gorty,
And, they will be wobbly Jellyfish of course. Since it's supposed to be composed of ice, I can't see a liquid ocean, maybe a slush puppy though..if there is any heat at all generated by friction.

a reply to: smurfy

Hi smurfy , It may well be kept liquid by friction.

Such an ocean on Mimas would be a surprise, as most of the core heat needed to keep water liquid would probably be lost through the moon's icy shell. But friction inside the moon caused by Saturn's gravity and Mimas's extremely eccentric orbit might melt the ice and preserve the ocean
www.newscientist.com...

originally posted by: gortex
a reply to: smurfy

Hi smurfy , It may well be kept liquid by friction.

Such an ocean on Mimas would be a surprise, as most of the core heat needed to keep water liquid would probably be lost through the moon's icy shell. But friction inside the moon caused by Saturn's gravity and Mimas's extremely eccentric orbit might melt the ice and preserve the ocean
www.newscientist.com...

Well now,
The BBC sure was economical with the info compared to the 'New Scientist' link. You can see now that there are actually differing favoured opinions, still I suppose that's healthy except Nimmo, I didn't notice mentioned in the BBC report.

Looks like there is a big chunk missing of the crust, of course it would wobble.

originally posted by: TinfoilTP
Looks like there is a big chunk missing of the crust, of course it would wobble.

That was considered and dismissed by the team

First, the team tested whether the extra rotation could be explained by a deformity underneath the enormous Herschel Crater, one-third the size of Mimas itself, which gives the moon its signature appearance. But even a "huge mass anomaly" created by the wallop that left the crater would not deliver the amount of movement that Dr Tajeddine's team had observed.

originally posted by: gortex

originally posted by: TinfoilTP
Looks like there is a big chunk missing of the crust, of course it would wobble.

That was considered and dismissed by the team

First, the team tested whether the extra rotation could be explained by a deformity underneath the enormous Herschel Crater, one-third the size of Mimas itself, which gives the moon its signature appearance. But even a "huge mass anomaly" created by the wallop that left the crater would not deliver the amount of movement that Dr Tajeddine's team had observed.

Whatever "womped" it, could be a dense object that penetrated to the edge of the core, producing an oblong core.

originally posted by: gortex
a reply to: smurfy

Hi smurfy , It may well be kept liquid by friction.

Such an ocean on Mimas would be a surprise, as most of the core heat needed to keep water liquid would probably be lost through the moon's icy shell. But friction inside the moon caused by Saturn's gravity and Mimas's extremely eccentric orbit might melt the ice and preserve the ocean
www.newscientist.com...

I don't know - I once tried freezing an entire two liter bottle of water when the outside temperature was -32C
Even though the plastic bottle split, a central core of liquid water remained, even though it was frozen solid to two inches thick. It would seem that an ice planet would do the same. The gravitational pressure from the solid sheets of ice of the crust would create pressure in the mantle and core layers, and increased pressure causes temperature to rise.