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Mimas' surprise: Tiny moon holds young ocean beneath icy shell

67 points by wglb 3y ago

quickthrower2 3y ago
Mind blowing! What are the odds of life there? Would there be enough energy getting there to support complex life like maybe small fish? I guess the water is kept “warm” by some internal latent heat from the moon formation?
- adrianN 3y ago
  I'd guess tidal heating from orbiting Saturn.
heads 3y ago
Are there any examples of this kind of assertion turning out to be incorrect? I’m happy to be told this kind of libation analysis is (ahem) rock solid but it’s not easy to tell from the article. My understanding of the article and the plot is that the authors modelled how the moon ought to wobble if it has an ocean versus it does not have an ocean, and if it did then how does it wobble with either a thick crust or thin crust on top. The actual, observed wobbling is in the “has an ocean” part of the plot therefore, assuming the model is correct and there isn’t some other cause of wobble, it probably has an ocean. This is the only evidence so far though — other than this data there is “no hint of an ocean underneath”. It would also wobble if it had a moon-mouse dance party at each pole. Modelling for different sized discos and different tempo dance music, we see that the observed wobbling is consistent with 4 billion mouse / 185bpm portion of the plot. I could also plot the hypothesised size of the kraken mouth which swallows ships as they vanish over the Earth’s horizon. The plot shows the rates at which the ship sinks from view based on kraken mouth size. The observed sink rate is consistent with a 12m wide kraken mouth which is a cool result except that ships sink over the horizon because the Earth is round. There are no krakens!
- card_zero 3y ago
  OK, but there are oceans, on moons. Therefore, ocean.
  - andrewflnr 3y ago
    Yeah, the closer analogy would be if multi-kilometer krakens were already a documented phenomenon.
- jl6 3y ago
  > Are there any examples of this kind of assertion turning out to be incorrect? Yes - for example, Ptolemaic epicycles. A model that explained the observed motion, but turned out not to be reality based.
  - lloeki 3y ago
    Were they incorrect? Seems like they were rather needlessly complex because of the earth-bound parameters. IOW if you take the simpler heliocentric motion equations and want to make your life miserable by changing the reference frame to be geocentric you'd land up on epicyclic equations. So even though the math is borne out of a misguided anthropocentric cosmology it does matches reality to a crude but reasonable approximation, unlike a edge-of-disc kraken.
    - jl6 3y ago
      Depends what you mean by incorrect. If the goal is to predict planetary movement, then epicycles might be a useful tool, just like an ocean-bearing moon model might be useful for predicting the wobble of Mimas. But as an explanation of what’s really happening, centering the universe on Earth is not a lot better than positing that kraken.
      - lloeki 3y ago
        Incorrect as in the kraken doesn't exist. The celestial objects do, the equations are valid not just superficially from observation, but deeper as they do encode gravitational laws, if only in a very obscure way due to the reference frame. A better kraken would be aether theories, whether luminiferous or mechanical gravitational, which survived all the way to the 19th century and mystified Lorentz and Maxwell (esp. the Mickelson experiment results), and even in the 20th initially by Einstein until he gave up on the idea in 1905.
deleted 3y ago
[deleted]
clort 3y ago
Wikipedia has some more information about this moon I've not previously heard of. The moon itself is composed largely of water ice and the liquid part is 15-20km under the surface. Mimas is responsible for the gap between Saturns widest rings and as you expect is splattered with craters, the largest of which is nearly 1/3 diameter of the whole moon. Looks like a disguised (or dilapidated!) Death Star.
TaylorAlexander 3y ago
Meanwhile JPL has laid off 570 people this week thanks to a failure to properly pass a budget in congress. [1] I’ve been watching For All Mankind this month and it’s remarkable how different things could be, but we can’t muster the will to really move things forward. [1] https://www.msn.com/en-us/news/technology/congressional-budget-gridlock-leads-to-stunning-nasa-layoffs/ar-BB1hW4r7 https://www.msn.com/en-us/news/technology/congressional-budg...
- phh 3y ago
  > I’ve been watching For All Mankind this month and it’s remarkable how different things could be, but we can’t muster the will to really move things forward. I love that show, but I think it's completely unrealistic. We couldn't have kept the pace, going to Mars would probably have cost 80% of the GDP, and a station simply impossible. It's now much easier to go to space because we had time to integrate/scale up the production we were using for space into the "normal" productions. (note that I'm not saying we didn't live a space winter that hindered space discovery)
  - simmerup 3y ago
    Wasn’t the lynchpin of For all Mankind was that there was some type of material on the moon we could mine for energy like oil and that funded future endeavours
    - ghaff 3y ago
      The "unobtainium" thing was at least a handwave that this is all less outlandish than it seems. Still, the earlier seasons seemed more natural extrapolations of this timeline with relatively few changes.
    - BuyMyBitcoins 3y ago
      The show also hand waived the invention of fusion in the 1980’s.
      - 3y ago

67 points by wglb 3y ago

Mind blowing! What are the odds of life there? Would there be enough energy getting there to support complex life like maybe small fish? I guess the water is kept “warm” by some internal latent heat from the moon formation?

adrianN 3y ago
I'd guess tidal heating from orbiting Saturn.

heads 3y ago

Are there any examples of this kind of assertion turning out to be incorrect? I’m happy to be told this kind of libation analysis is (ahem) rock solid but it’s not easy to tell from the article. My understanding of the article and the plot is that the authors modelled how the moon ought to wobble if it has an ocean versus it does not have an ocean, and if it did then how does it wobble with either a thick crust or thin crust on top. The actual, observed wobbling is in the “has an ocean” part of the plot therefore, assuming the model is correct and there isn’t some other cause of wobble, it probably has an ocean. This is the only evidence so far though — other than this data there is “no hint of an ocean underneath”. It would also wobble if it had a moon-mouse dance party at each pole. Modelling for different sized discos and different tempo dance music, we see that the observed wobbling is consistent with 4 billion mouse / 185bpm portion of the plot. I could also plot the hypothesised size of the kraken mouth which swallows ships as they vanish over the Earth’s horizon. The plot shows the rates at which the ship sinks from view based on kraken mouth size. The observed sink rate is consistent with a 12m wide kraken mouth which is a cool result except that ships sink over the horizon because the Earth is round. There are no krakens!

card_zero 3y ago
OK, but there are oceans, on moons. Therefore, ocean.
- andrewflnr 3y ago
  Yeah, the closer analogy would be if multi-kilometer krakens were already a documented phenomenon.
jl6 3y ago
> Are there any examples of this kind of assertion turning out to be incorrect? Yes - for example, Ptolemaic epicycles. A model that explained the observed motion, but turned out not to be reality based.
- lloeki 3y ago
  Were they incorrect? Seems like they were rather needlessly complex because of the earth-bound parameters. IOW if you take the simpler heliocentric motion equations and want to make your life miserable by changing the reference frame to be geocentric you'd land up on epicyclic equations. So even though the math is borne out of a misguided anthropocentric cosmology it does matches reality to a crude but reasonable approximation, unlike a edge-of-disc kraken.
  - jl6 3y ago
    Depends what you mean by incorrect. If the goal is to predict planetary movement, then epicycles might be a useful tool, just like an ocean-bearing moon model might be useful for predicting the wobble of Mimas. But as an explanation of what’s really happening, centering the universe on Earth is not a lot better than positing that kraken.
    - lloeki 3y ago
      Incorrect as in the kraken doesn't exist. The celestial objects do, the equations are valid not just superficially from observation, but deeper as they do encode gravitational laws, if only in a very obscure way due to the reference frame. A better kraken would be aether theories, whether luminiferous or mechanical gravitational, which survived all the way to the 19th century and mystified Lorentz and Maxwell (esp. the Mickelson experiment results), and even in the 20th initially by Einstein until he gave up on the idea in 1905.

deleted 3y ago

[deleted]

clort 3y ago

Wikipedia has some more information about this moon I've not previously heard of. The moon itself is composed largely of water ice and the liquid part is 15-20km under the surface. Mimas is responsible for the gap between Saturns widest rings and as you expect is splattered with craters, the largest of which is nearly 1/3 diameter of the whole moon. Looks like a disguised (or dilapidated!) Death Star.

TaylorAlexander 3y ago

Meanwhile JPL has laid off 570 people this week thanks to a failure to properly pass a budget in congress. [1] I’ve been watching For All Mankind this month and it’s remarkable how different things could be, but we can’t muster the will to really move things forward. [1] https://www.msn.com/en-us/news/technology/congressional-budget-gridlock-leads-to-stunning-nasa-layoffs/ar-BB1hW4r7 https://www.msn.com/en-us/news/technology/congressional-budg...

phh 3y ago
> I’ve been watching For All Mankind this month and it’s remarkable how different things could be, but we can’t muster the will to really move things forward. I love that show, but I think it's completely unrealistic. We couldn't have kept the pace, going to Mars would probably have cost 80% of the GDP, and a station simply impossible. It's now much easier to go to space because we had time to integrate/scale up the production we were using for space into the "normal" productions. (note that I'm not saying we didn't live a space winter that hindered space discovery)
- simmerup 3y ago
  Wasn’t the lynchpin of For all Mankind was that there was some type of material on the moon we could mine for energy like oil and that funded future endeavours
  - ghaff 3y ago
    The "unobtainium" thing was at least a handwave that this is all less outlandish than it seems. Still, the earlier seasons seemed more natural extrapolations of this timeline with relatively few changes.
  - BuyMyBitcoins 3y ago
    The show also hand waived the invention of fusion in the 1980’s.
    - 3y ago