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A newly discovered moon tunnel

washingtonpost.com

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Re: A newly discovered moon tunnel

#91

Post by comicjk »

kurthr wrote: post #64
samstave wrote: post #54

Earlier quoted context omitted.

Under what circumstances does one need to have in order to make them combine into water, organically? (Meaning without any device or machine, assume you have two big clouds of each element floating in space - if they collide, do the naturally just form into water molecules?)

At reasonable temperatures, yes, the clouds turn into water and release energy, hydrogen burns. Water is entropically preferred as a lower energy state than separate atoms/molecules because of lower enthalpy at reasonable temperatures. Depending on density and ignition sources the reaction rate may vary, but it doesn't have to explode in a ms when there is a billion years available.

That's not what "entropically preferred" means. If something is a lower-energy state, it's energetically preferred, but may or may not be entropically preferred. Water is NOT - entropy would prefer simpler molecules over more structured molecules.

I think the concept you're thinking of is free energy, which determines the final destination of a process. The equation relating these things is (change in free energy) = (change in energy) - temperature × (change in entropy). Entropy only becomes the dominant component when temperature is high. And, as expected, water molecules dissociate at high temperature.

Re: A newly discovered moon tunnel

#92

Post by millettjon »

QAPereo wrote: post #89
ballenf wrote: post #22

Earlier quoted context omitted.

The article mentions the use of inflatable housing inside. Seems like a wise move given we have so little experience with their stability. If they've survived this long, then presumably they are very unlikely to collapse on their own. That is, settlers would only need to worry about collapse cause by their own movements. The odds of them being 'on the verge of collapse' are relatively low in my thinking. Unless there…

The moon is pretty dead, so no processes exist... if they’re stable, barring asteroid strike. They’d remain stable. The problem is metastability, the “death block” problem in ice climbing.

There are moonquakes so not completely dead. https://www.nasa.gov/exploration/home/15mar_moonquakes.html

Re: A newly discovered moon tunnel

#93

Post by ealloc »

DougWebb wrote: post #73
ealloc wrote: post #65

Earlier quoted context omitted.

The reason water exists on earth, and not on mars, may be that life on earth saved the water by discovering photosynthesis. The discovery of photosynthesis caused the "great oxygenation event" which pumped oxygen into the atmosphere. Oxygen reacts with atmospheric hydrogen to form water. Without the oxygen, the very light hydrogen molecules would float to the top of the atmosphere and are easily blown away by solar w…

That seems like it must be incorrect. Life on earth evolved in the oceans, so the oceans had to exist for eons before life evolved and the eons it took for life to evolve photosynthesis and produce significant amounts of oxygen in the atmosphere. If what you're saying is correct, then the earth either started out with much more water than it has now, or the hydrogen escaped a lot more slowly than I'd expect it to.

The book was written in 2002, and I just looked up Nick lane's latest 2016 take on it here: [1]

His point in this new article is that instead of one big "oxygenation event" there may have been multiple. But he sticks to his story that the creation of an ozone layer by photosynthesis was the key step in saving the oceans. He argues both Mars and Earth had oceans originally (confirmed by Mars Satellite observations), which were gradually diminished by a process in which ultraviolet light splits atmospheric water, minerals on the surface absorbed the oxygen (rusting, making Mars red) leaving the hygrogen to blow away. But life on earth pumped extra oxygen into the atmosphere, faster than minerals could aborb it, creating the reactive ozone layer which prevented hydrogen from blowing away, thus saving the oceans from their fate on Mars.

[1] nick-lane.net/wp-content/uploads/2016/12/Oxygen-and-life.pdf

Re: A newly discovered moon tunnel

#95

Post by lrdd »

samstave wrote: post #28
wyager wrote: post #26

Earlier quoted context omitted.

The moon’s gravity isn’t strong enough to hold water vapor or any other atmospheric gas. It would either get siphoned off by the earth or just fly off into the solar system. The same is true of earth and helium.

Ok, and I like the comment about helium... But where did water originate?

I think the short answer is we don't really know, but the simplest explanation is muddy icy comets colliding

Re: A newly discovered moon tunnel

#96

Post by rbanffy »

moomin wrote: post #3

Sounds like we need to send a probe or ten to the Moon. Who knows what’s down there? (Although the answer is going to be “some rocks” as far as most non-astronomers are concerned.)

Probably ice. Ice that falls into the entrance and then sublimates has a good chance of moving to perpetual darkness regions and to stay there. Factor a couple billion years and you probably will have a decent amount.

Now imagine there is some simple biology happening from the time the Moon had some atmosphere, in caves sealed billions of years ago.

Re: A newly discovered moon tunnel

#97

Post by u801e »

spdustin wrote: post #60
samstave wrote: post #19

Earlier quoted context omitted.

If the moon had ancient volcanic activity and thus, why is it, after observable impact from various bodies - shown in the craters all over the surface, and the sumizing of the fact that water was deposited to earth from extra-orbital impacts... does the moon have zero water or atmosphere? Where did water originate? (I didn't know how to format that question any better, so please forgive the fumbly format)

The moon's core isn't made of the swirling molten iron dynamo like Earth's is. No swirling molten iron, no magnetic field. No magnetic field, nothing deflects the solar wind that then, literally, blows away any fledgling atmosphere. It's believed that Mars' atmosphere was considerably more dense than it is today, but along the way, its core cooled, and it lost its protective magnetic shield, allowing the solar wind t…

I've read that it's the same case with Venus' core, but its atmosphere is far more dense than either Earth's or Mars'.

Re: A newly discovered moon tunnel

#98

Post by yeukhon »

FreeFull wrote: post #16
saagarjha wrote: post #14

> And many scientists have long dreamed of building bases inside natural moon caves, where lunar explorers might sleep safely in inflatable homes, protected from the storms above. What "storms" are the authors talking about here?

Maybe solar storms? The Sun sends out quite a lot of radiation from time to time. Earth is protected by its magnetic field and atmosphere, the Moon and Mars not so much.

Am I incorrect without an active lava core, the magnetic field is basically non-existient? Then Moon tunnel is probably not good enough for humans to remain healthy.

Re: A newly discovered moon tunnel

#99

Post by yeukhon »

DougWebb wrote: post #78
ballenf wrote: post #27

Earlier quoted context omitted.

Are there any figures on the minimum $/gram of minerals that would justify a mining mission (presumably unmanned)? Just can't imagine that gold, platinum or any stable metal would be worth it. Maybe high grade diamonds that don't need to be extracted from other rock. The surveys would have likely identified the presence of such a high density substance and we haven't seen any mention of it. I know you probably meant…

The most common elements on the moon are quite common on the earth too; I don't think the value in mining them will ever come from bringing the mined materials back to earth. The value is going to come from having and maintaining an established base on the moon. The moon is a high point in the earth's gravity well that's full of raw materials that can be used to build things that can go further out. Mining on the moo…

Though a jewelry made from Moon elements would probably have a ten-fold price tag than the Earth’s counterpart, because it’s from the Moon.

Re: A newly discovered moon tunnel

#100

Post by samstave »

lrdd wrote: post #95
samstave wrote: post #28

Earlier quoted context omitted.

Ok, and I like the comment about helium... But where did water originate?

I think the short answer is we don't really know, but the simplest explanation is muddy icy comets colliding

If that's the case, why haven't we been hit by any in recorded history that gave us more water?

How many comets have hit us that were rife with water supplies to provide the amount of water earth has given that water isn't also abundant on planets that are much larger, like Jupiter?

Why do we see planets with atmospheres of say sulfer, and earth doesn't have an issue with sulfer in the atmosphere?

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