Mimas' surprise: Tiny moon holds young ocean beneath icy shell | Hacker News Reader

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

phys.org

67 pointswglb25 comments

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-budg...

> 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)

When SpaceX was new almost everyone said the same about what was "realistic". I don't think it's about time to scale up so much as about finding and executing on better approaches.

I agree it would have had to be done differently and not just by spending more (if that's how you take "muster the will").

Added: John Walker (RIP) wrote in 1993 about such an alternate strategy and against this conventional wisdom that space launch is just inherently astronomically expensive per kg to orbit: https://www.fourmilab.ch/documents/rocketaday.html

That wisdom was still conventional 1-2 decades later.

The inflation adjusted cost of the moon program for 13 years was $19.76 billion per year in 2020 dollars.[1] At the time it was 4.4% of the federal budget.

I see absolutely no reason why, if they had not continued, they would have somehow needed 80% of GDP to set up a permanent base. It seems they got the entire moon program done for way, way less and indeed we ended up eventually building and keeping occupied the international space station. The additional effort to do the same thing on the moon would not somehow swallow all government expenditures.

I mean hell consider what we have spent on unnecessary wars and our inflated military budget. There absolutely could have been an alternate timeline where we were focused on space expansion and not purely military expansion.

[1] https://www.planetary.org/space-policy/cost-of-apollo

[2] https://www.cbsnews.com/news/apollo-11-moon-landing-how-much...

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

It was Helium-3.

Potentially useful for certain types of fusion.

https://en.wikipedia.org/wiki/Aneutronic_fusion#Candidate_fu...

And maybe cooling certain types of quantum computer.

https://en.wikipedia.org/wiki/Dilution_refrigerator

Moonshine (2010) remains the definitive write-up on (against) Helium-3 for me, from sci-fi notable Charles Stross.

> He 3 is not magic high-energy pixie dust. And in the context of the space colonization debate it should be seen for what it is — a placeholder for the alchemist's stone that will turn the money-hole of a lunar colony into a profit centre: an extractable natural resource that can't be found on earth and is valuable enough to mine elsewhere.

https://www.antipope.org/charlie/blog-static/2010/08/moonshi...

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.

The show also hand waived the invention of fusion in the 1980’s.

Yeah, they sort of had a maximum timeline set by what they could reasonably do with some makeup for the cast and them not being unreasonably old for their roles. But telling the story they wanted probably required an unnatural rate of technology advance over that period of time.

It's interesting because there is broad agreement that we could have had fusion power if we had actually invested in it, which could have more plausibly happened if we were also investing in a space race (and so society was more science and engineering focused). In the show they claim that the invention of fusion was the product of one smart guy, which isn't how it would have gone, but the actual presence of fusion seems plausible to me.

Only partly thanks to overall budget inaction in Congress. The bigger cause in my opinion is Congress proposing huge reductions in Mars Sample Return program funding or outright cancellation [1], which is currently supporting a lot of people at JPL. This coincides with a scathing review of the program [2]. I think the vitriol is justified, especially after the two-decade-long shitshow that was JWST.

[1] https://arstechnica.com/space/2023/07/the-senate-just-lobbed... [2] https://www.nasa.gov/wp-content/uploads/2023/09/mars-sample-...

If only the russians planned some mission to mimas, we'd have a budget in days.

The space exploration, which was once considered inspiring and noble, now is seen primarily as an investment diversification strategy of a bored billionaire with a very questionable character.

Unfortunately it's inevitable the conclusion that the humanity's road to the future is not monotonic in terms of progress and that looking at the past as better than today is not always a kind of nostalgic bias.

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.

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?

I'd guess tidal heating from orbiting Saturn.

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!

OK, but there are oceans, on moons. Therefore, ocean.

Yeah, the closer analogy would be if multi-kilometer krakens were already a documented phenomenon.

> 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.

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.

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.

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.

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