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Water Found Deep Inside the Moon

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Re: Water Found Deep Inside the Moon

#161

Post by cwkoss »

s_kilk wrote: post #144
keenerd wrote: post #139

Earlier quoted context omitted.

I'm having trouble thinking of catastrophes that could take out both. Well, I can think of a few (bio-weapon, nearby supernova) but they would take out a Mars colony just as easily.

I think they meant that if we have civilisation collapse on Earth then the Lunar folk are screwed too, because their supplies would be cut off permanently.

Depends how much supply they have. A mature lunar colony should have a stockpile and equipment sufficient for reconstructing any equipment needed.

At that point, asteroid mining may be cheaper than launching resources from earth.

Re: Water Found Deep Inside the Moon

#162

Post by cpeterso »

athenot wrote: post #34
QAPereo wrote: post #16

Earlier quoted context omitted.

Inasmuch as Mars with our current technology offers no back up for civilization, the same can certainly be said for the moon. I would argue over that the moon actually has some benefits Mars lacks, in addition to proximity it has a much lesser gravitational field and therefore a much lower delta V. Moon colony could realistically jumpstart space and vacuum industries beyond LEO, and frankly it would probably give us…

When the topic of Backup for Civilization comes up, instead of Wall-E, I tend to think of Elysium, i.e. the backup option is only for the wealthy, leaving the rest in a worse state. https://www.space.com/22287-elysium-space-station-science-na...

For another take on backing on human civilization, check out Neal Stephenson's novel Seveneves. Humanity evacuates 1500 people to orbit as moon debris decimates all remaining life on the earth's surface. As a story, it's pretty dry, but as a thought experiment, it's very interesting.

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

Re: Water Found Deep Inside the Moon

#163

Post by ribosometronome »

kbenson wrote: post #92
ribosometronome wrote: post #88

Earlier quoted context omitted.

Why is humanity's survival important?

It's important for the exact same reason you're able to ask that question. Without humanity, who asks why? Humanity is, to the best of our knowledge, the best and possibly only chance of increasing understanding of the universe. I care about that, as well as about our species generally in what is likely an evolved and chemically reinforced way. At some point that may be less true, and I would care less (but would sti…

It sounds like you value the persistence of understanding in a way that just isn't particularly important to me. The survival of my loved ones -- and that's a category that can go across species -- is absolutely important to me. The survival of evil space Nazis? Eh.

That said, I also don't really think I see being an evolutionary dead end as too huge of a concern. Many of us appreciate things that aren't truly keen from an evolutionary perspective. Consider how many of us will remain happily childless (perhaps not yourself) well into our 30s and beyond. Not amazing for propagating our own personal genes and yet, they're decisions we actively and happily make.

Re: Water Found Deep Inside the Moon

#164

Post by shakna »

yohui wrote: post #98
HugoDaniel wrote: post #38

Earlier quoted context omitted.

Lets hope they don't find oil there...

As you probably know, that's impossible since fossil fuels (as the name suggests) are formed from the remains of prehistoric organisms. Since the Moon is lifeless, it has no fossil fuels. But I wouldn't mind if the moon did experience a resource rush (unless it sparked a conflict). At least we would finally get to see a moon base.

Fossil fuels are known as biogenic oils or the like.

It has been theorised, but neither proven nor disproven, that abiogenic oils might exist. (Earth is likely only the biogenic kind, but other planets may differ).

That is to say, petroleum compounds can be formed without the need for biological materials, but rather through pressure, heat, and bedrock.

Re: Water Found Deep Inside the Moon

#165

Post by hnlmorg »

andyfal12 wrote: post #142
hnlmorg wrote: post #78

Earlier quoted context omitted.

This is one of the biggest points people miss when talking about civilization back ups. I tend to think of it in IT terms: the moon is like an offline but onsite backup. It will protect you from most internal cockups where as Mars is more like an offsite backup which will protect you should your building (Earth) get taken out

Meteor impacts and supervolcanoes seem to be the near-term worst case scenarios, neither which change the state of living on the moon. I don't know that the metaphor of them being under the same roof works.

I know the risks are astronomical (literally), but anything significant enough to alter Earth's mass would also alter the moons orbit.

I just think if we are talking about an extraterrestrial base for the sake of "backing up" the human race then it is prudent to pick a location that isn't in any way dependant on the master copy.

However I appreciate other concerns also take priority as well (cost, practicality, etc) but if the topic were strictly just about backing up humanity then my ideal candidates would be Mars plus some location outside of our solar system. But I'm venturing well into the realm of sci-fi now.

Re: Water Found Deep Inside the Moon

#166

Post by boznz »

perseusprime11 wrote: post #61
tambourine_man wrote: post #7

I've always been more excited about a Moon colony than a Mars one. I mean, compared to Mars, the Moon is ridiculously close. Many of the same benefits Musk seeks (backup for Civilization, excitement) for a fraction of the cost. Low gravity and atmosphere on a dome would be more complicated, but again, compared to Mars, it's right there . It would be a more humble and realistic first step, IMO.

So, why is Elon Musk not excited about Moon?

As an amateur Musk watcher I actually think he will be interested in the moon or more likely some sort of permanent space station as I think he's only now realizing how difficult mars would be as a first goal (also he's very good at surprises)

Re: Water Found Deep Inside the Moon

#167

Post by simonh »

keenerd wrote: post #75
Obi_Juan_Kenobi wrote: post #69

Earlier quoted context omitted.

Mars has atmosphere for aerobraking and ISRU possibilities that the moon does not. In many ways, it is much more practical from a spaceflight standpoint. That's not to say that there aren't possibilities for both, but Mars is seen as the preferred choice for a variety of sound reasons.

The Martian atmosphere is next to worthless for aerobraking human-scale infrastructure. One of the most significant points in the Moon's favor is the (relative) ease with which a space elevator could be built. It doesn't need unobtainium, current structural materials are strong enough.

SpaceX have run the simulations and while Red Dragon is possible, there's no way they can adapt Dragon to land on the Moon without adding an extra stage. That difference is entirely down to Aerobraking. Even the thin atmosphere of Mars makes a huge difference.

Anyone who plays KSP can confirm this for you, especially using the Real Solar System mod, though the same lessson is apparent even in the stock game.

Re: Water Found Deep Inside the Moon

#168

Post by simonh »

boznz wrote: post #134
thescriptkiddie wrote: post #131

Earlier quoted context omitted.

I'm all for building Lunar outposts, but colonization is not really practial. Luna simply doesn't have the natural resources to sustain a civilization. Yes there is water in the regolith, but nowhere near as much as on Mars. And critically, Carbon, Nitrogen, Phosphorus, and Sulfur are only present in trace amounts. Nearly all of the elements essential to life will have to be imported, either from Earth, from Mars, or…

"Carbon, Nitrogen, Phosphorus, and Sulfur are only present in trace amounts" Is this because we havent found them yet, an educated guess or the moon somehow gets rid of these?

The moon was mostly cast off from the Earths upper crust during an impact when earth was still forming. As a result it's mostly composed of lighter materials and lacks heavier metals and elements brought the the surface on Earth due to magma flows in the mantle and vulcanism.

Re: Water Found Deep Inside the Moon

#169

Post by simonh »

keenerd wrote: post #152
rory096 wrote: post #138

Earlier quoted context omitted.

>thin enough it won't help you slow down - much. No. It's thin enough you can't land with parachutes alone. It's still enough that Mars Global Surveyor used it to make up a 1,250 m/s delta-v deficit. Is landing on Mars more complex than a thick atmospheric landing on parachutes or an exoatmospheric landing on propulsion only? Yes. But the atmosphere still saves you a lot of delta-v. [0] https://mars.jpl.nasa.gov/mgs/…

> It's still enough that Mars Global Surveyor used it to make up a 1,250 m/s delta-v deficit. It took MGS 15 months (not counting delays) of aerobraking to do that. MGS only weighed 1000kg too. Maybe it could work for shipping large, pre-assembled, empty hab modules to Mars before people get there. (Low density, higher drag, no rush.) But not practical for actual human bodies or even resupply since the Hohmann transf…

It only took that long because MGS was aerobraking into orbit and wasn't designed to survive the stress of lower atmosphere turbulence, so only used the uppermost layer of the atmosphere for braking. If your going to land, obviously you get to use all the atmosphere and also can use parachutes. Something a problem braking into orbit can't do.

Surface probes do direct descent trajectories. There is no extended series of repeated braking passes. You do it in one go.

Re: Water Found Deep Inside the Moon

#170

Post by drostie »

codesnik wrote: post #135
drostie wrote: post #108

Earlier quoted context omitted.

I'm glad you asked! So there's an important physics reason why the equator is warm and the North and South poles are cold on this planet, and it has to do with how you point a surface. If you ever find yourself in a dark office with a bright desk lamp (or maybe your home office or kid's bedroom might be suitable) you might even try this experiment: take a flat surface, a notepad or steno pad, and hold it up facing th…

why general relativity makes mercury tidal locking wrong? I've heard it's not 1:1, but I don't see any connection

Actually looking into it a bit more to answer your question, I'm entirely confusing two different things. Mercury is tidally locked 3:2, it rotates 3 times for each 2 times it orbits -- but that is a result of history and not general-relativistic corrections, which are necessary to explain a different value (the precession of its orbit).

In fact our best understanding of why Mercury has the 3:2 relationship appears to be (if I'm reading these papers right) "because of historical reasons." That is, now that it's in that state, that state is stable and unlikely to decay to the 2:1 or 1:1 state, but getting into that state is much less clear and potentially requires that in the past, the other planets of the Solar system had nudged Mercury into a more eccentric orbit than it has now. The claim is that the eccentricity of that orbit caused the 3:2 resonance, then in more recent history these perturbations from other planets averaged out more to make Mercury's orbit less eccentric, but it still holds on to the resonance from its past.

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