50 km long cave discovered on moon

[cubinator]

9 hours ago, kerbiloid said:

Also, unlikely just filling that tube with air would work, the air would dissipate through numerous leaks. So, anyway pressurized hulls would be required.

You would also need something like millions of tons of air to fill an entire cave 50 km long.

[Ultimate Steve]

5 hours ago, cubinator said:

You would also need something like millions of tons of air to fill an entire cave 50 km long.

Good point. Hmm, I know you can get oxygen on the Moon by electrolyzing water ice, but I'm not sure about nitrogen...

[GDJ]

6 minutes ago, Ultimate Steve said:

Good point. Hmm, I know you can get oxygen on the Moon by electrolyzing water ice, but I'm not sure about nitrogen...

And theoretically zapping CO2 with enough laser power to split carbon and oxygen, but the risk is O and CO (carbon monoxide).

Heat, CO2 and plants I guess.

As far as Nitrogen we could tank it up to the moon. There would be no impact on Earth filling a cavern this size with Nitrogen (given the size of the cavern vs all the atmosphere on Earth).

 

[cubinator]

13 minutes ago, Ultimate Steve said:

Good point. Hmm, I know you can get oxygen on the Moon by electrolyzing water ice, but I'm not sure about nitrogen...

There's not a lot of nitrogen on the Moon...

4 minutes ago, GDJ said:

As far as Nitrogen we could tank it up to the moon. There would be no impact on Earth filling a cavern this size with Nitrogen (given the size of the cavern vs all the atmosphere on Earth).

 

Yeah but like I said you have to bring millions of tons of nitrogen if you want to fill an entire tube. That would need a lot of rockets and for not necessarily much benefit.

[PB666]

9 minutes ago, Ultimate Steve said:

Good point. Hmm, I know you can get oxygen on the Moon by electrolyzing water ice, but I'm not sure about nitrogen...

you don have to fill the whole cave, just block off sections. Find or make a smaller lava hole. Build a air tight wall on both sides of the lava hole; this will require circumcising the tub until solid rock is reached. The each wall  will be connected by a submarine door (or two). Fill the lava hole with moon dust, packing the dust as it fills, as it fills there are empty gas bags distributed at even intervals the bags will be laid out vertically hanging circles and connected to a pressurization system, rigid enough to withstand a couple of atmospheres of pressure. in areas with gaps between circular bags chains would connect the two walls with force sensors on the chains. Once the dust is compacted the lava tube/manhole is capped. As the the most distal chamber is inflated the pressure in the bags is increased so that the balance of pressure on both sides of the wall is the same. This could be done simulataneously at many spots to create a pressure gradient.

BTW the material that comprises the lava tube walls is expected to be toxic to humans since the tubes have crumbly material it would need to be dressed. Thus there would need to be a way to coat the walls with an oxygen resistant material. Likewise sealing the walls to the pressure walls. Most of the cements used on earth would not stand up to the vacuum of space, so pressurization with nitrogen during application may be needed. 

[Azimech]

25 minutes ago, Ultimate Steve said:

Good point. Hmm, I know you can get oxygen on the Moon by electrolyzing water ice, but I'm not sure about nitrogen...

If only we could build some kind of "electrostatic conduit" to transport the atoms from Earth to the Moon.

[kerbiloid]

8 hours ago, PB666 said:

you don have to fill the whole cave, just block off sections. Find or make a smaller lava hole. Build a air tight wall on both sides of the lava hole; this will require circumcising the tub until solid rock is reached. The each wall  will be connected by a submarine door (or two). Fill the lava hole with moon dust, packing the dust as it fills, as it fills there are empty gas bags distributed at even intervals the bags will be laid out vertically hanging circles and connected to a pressurization system, rigid enough to withstand a couple of atmospheres of pressure. in areas with gaps between circular bags chains would connect the two walls with force sensors on the chains. Once the dust is compacted the lava tube/manhole is capped. As the the most distal chamber is inflated the pressure in the bags is increased so that the balance of pressure on both sides of the wall is the same. This could be done simulataneously at many spots to create a pressure gradient.

And then build same multi-storey buildings inside like they would build on the surface, just their windows may be not sealed.
And then reinforce the tube walls, which are not a single crystal with a wormhole inside, but are full of cracks and numerous leaks.

And then I see 2 cases:

Plan A.
Finally have built a 100 m high artificial pattern/structure filling the lava tube.
Then why use this tube at all? 95% of this building doesn't need any cave. It needs only to build 5% more - a strong wall and roof.
Oops. Such large structure should anyway be built from thick and strong elements, and 1 atm pressure from inside is even not a workload for them.
A natural cave gives nothing to it.
(I mean here something like the lunar complex from Iron Sky  movie).

Plan B.
Occupy just the very floor of this cave, having 100 m of empty space above head.
Though, they still have to reinforce full surface of the cave, and not sure if a 100 m high cave ceiling gives more inspiring feeling than a 100 m high artificial ceiling.
Anyway, it's much easier to make this town more compact and return to Plan A.

So, I can see no case when a huge cave is useful as a place for living.
Don't be confused by the Earth underground complexes. They have air all around, they don't have to be pressurized, they just need a ventilation.

Open excavations, craters, pressurized buildings inside, thin regolith coat above give the same, but much easier.

P.S.
I was loving dwarvish-like underground fortresses before I've played Minecraft.
It was like an icy shower on my head. Mountains and undergrounds only look monolith, but they are just porous mounds. Huge ziggurats are much better.

Edited October 23, 2017 by kerbiloid

[magnemoe]

3 hours ago, kerbiloid said:

And then build same multi-storey buildings inside like they would build on the surface, just their windows may be not sealed.
And then reinforce the tube walls, which are not a single crystal with a wormhole inside, but are full of cracks and numerous leaks.

And then I see 2 cases:

Plan A.
Finally have built a 100 m high artificial pattern/structure filling the lava tube.
Then why use this tube at all? 95% of this building doesn't need any cave. It needs only to build 5% more - a strong wall and roof.
Oops. Such large structure should anyway be built from thick and strong elements, and 1 atm pressure from inside is even not a workload for them.
A natural cave gives nothing to it.
(I mean here something like the lunar complex from Iron Sky  movie).

Plan B.
Occupy just the very floor of this cave, having 100 m of empty space above head.
Though, they still have to reinforce full surface of the cave, and not sure if a 100 m high cave ceiling gives more inspiring feeling than a 100 m high artificial ceiling.
Anyway, it's much easier to make this town more compact and return to Plan A.

So, I can see no case when a huge cave is useful as a place for living.
Don't be confused by the Earth underground complexes. They have air all around, they don't have to be pressurized, they just need a ventilation.

Open excavations, craters, pressurized buildings inside, thin regolith coat above give the same, but much easier.

P.S.
I was loving dwarvish-like underground fortresses before I've played Minecraft.
It was like an icy shower on my head. Mountains and undergrounds only look monolith, but they are just porous mounds. Huge ziggurats are much better.

benefit is that with the shielding from the cave you can use inflated or light structures, however you need an lift or something to get to the surface. 
Benefit will increase as base grow larger up to you use the cave itself.

Two immediate uses first is science, this is very old, 4 billion and something, second is chance for ice. 

[kerbiloid]

34 minutes ago, magnemoe said:

benefit is that with the shielding from the cave you can use inflated or light structures,

A multistorey building can not be an inflated or light structure. It anyway is made of heavy and strong construction elements.
You can have a look at any skyscraper, with its walls made of glass. Because of steel + reinforced concrete framework.
So, this benefit is negligible compared to the difficulties.

Edited October 23, 2017 by kerbiloid

[Cassel]

What if this is not a cave, but entrance?

 

[magnemoe]

7 hours ago, kerbiloid said:

A multistorey building can not be an inflated or light structure. It anyway is made of heavy and strong construction elements.
You can have a look at any skyscraper, with its walls made of glass. Because of steel + reinforced concrete framework.
So, this benefit is negligible compared to the difficulties.

None are talking high rise buildings, still you could probably build high enough with container like modules it would be pointless. 
As I said major base, Think south pole base not IIS, here you would want some larger open spaces if its cheap, both for comfort and for growing food. 

Science and optional resources would be more important also more room for future growth. 

[kerbiloid]

58 minutes ago, magnemoe said:

larger open spaces

Underground open spaces surrounded by vacuum?

58 minutes ago, magnemoe said:

both for comfort and for growing food. 

Lunar underground looks a little expensive place to build 2-storey cottages with lawns under 100 m high cave ceiling.
Their population density would be too low to give them any practical sense.
Imho, better imagine Lunatown as something like this:

Spoiler

, but covered.
(Entrances instead of the wharves, numerous greenhouses and facilities instead of those red buildings far behind the skyscrapers district, stone instead of the water.)
From aside - something like this:

Spoiler

To grow underground food you don't need empty space above the greenhouse, you need as many greenhouses packed inside the pressurized volume as possible, so a multi-storey stack of greenhouses, up to the ceiling.
So, only some recreation zones could be empty up to the ceiling.
But:
1) anyway they will fill its volume with galleries, attractions, hanging gardens, etc (to use the space and to hide the stone sky)
2) you can easily get the required empty space for parks between multi-storey buildings.

Edited October 23, 2017 by kerbiloid

[PB666]

You do not want a greenhouse on the surface of the moon for the reasons you say.

1. The moon has a light cycle, 15 days dark, 15 days light.

2. Plants do not light direct exposure to sunlight.

3. The moons surface temperature goes from deep space cold to several hundred degrees over the monthly cycle.

The whole reason for being underground is to modulate the extremes of space on the surface.

Ground = insulation from

heat and cold swings.
cosmic and high energy hv radiation.
A place to pressurize in which the chamber itself provides resistance to biogenic atmospheric pressures.

IN addition the best modern greenhouses use LED (about 4 red for 1 blue) for growth. Some apply tiny amounts of UV to control bugs.

Plants don't like green light, they slow growth in green light.

Instead you need a 15 day power storage system such as a H2 02 fuel cell, or lithium ion batteries.

[softweir]

12 hours ago, kerbiloid said:

A multistorey building can not be an inflated or light structure. It anyway is made of heavy and strong construction elements.
You can have a look at any skyscraper, with its walls made of glass. Because of steel + reinforced concrete framework.
So, this benefit is negligible compared to the difficulties.

On the moon. One-sixth gravity. In an enclosed volume.

There'd be no winds or rain, so no need for heavy walls, windows or roofs, just something to stop it feeling too open. You could clad it in any suitable thin material - opaque for walls, transparent for windows. The only "heavy" parts needed would be the floors, and they could be stupidly thin compared to those needed on Earth, since the occupants would weigh 1/6th that on Earth. All-in-all, the structural requirements of multi-storey buildings would be massively less than needed on Earth. And if building multi-storey is easy, then that reduces the need to seal long lengths of lava-tube, so it may be an economic proposition.

The real difficulty would be finding a suitable raw material on the moon and converting it into something we can build with that won't become a health hazard. Corrugated aluminium sheet would be a possibility for walls, floors and roofs, if enough energy could be sourced. Fuzed regolith has been floated as a building material, but are we sure it won't shed dust? Might such dust be as dangerous as asbestos? A lot of careful research would be needed on that topic.

[GDJ]

If we could get this to work in a vacuum and cold temperatures, spray the inside with LOTS of this:

http://aaaspray.com/spray-foam-insulation/

25PSI rated compressibility. Airtight, water tight. High R value for insulation.
Like I said, the trick is to get it to work in cold and vacuum.

[kerbiloid]

6 hours ago, PB666 said:

You do not want a greenhouse on the surface of the moon for the reasons you say.

1. The moon has a light cycle, 15 days dark, 15 days light.

2. Plants do not light direct exposure to sunlight.

3. The moons surface temperature goes from deep space cold to several hundred degrees over the monthly cycle.

I do not consider sunlight greenhouses on the Moon at all. As well as any glassy doom dome stuff.
When you have to save every bucket of water, hydroponics means everything. All the more when any "outer wall" must withstand vacuum, temeperature fluctuations, etc.
Only hydroponic chambers with an artificial light, hidden inside a pressurized volume.

And those chambers don't require empty sky above the head, but to save volume and mass they anyway should be multistorey.
When you already have built a multistorey greenhouse complpex, it weights enough to not worry about its outer walls mass.
And definitely such structure could be easier to build and maintain when it is on surface, not underground.

 

6 hours ago, softweir said:

On the moon. One-sixth gravity. In an enclosed volume.

On the moon a 30-storey building weights like a 5-storey on the Earth. And is also full with furniture, equipment, etc.

Also don't forget that regolith splitting requires a lot of energy, because alumina is one of the toughest substances in Universe.
So, whenever you can, instead of melting lunar aluminium, you should bake lunar regolith into a concrete, make bricks and build structures. It also increases mass.
Even if you melt pure metals, unlikely you would prefer to live in a building with paper-thin tin walls. So, some kind of brick buildings (rather than pressurized envelopes) is a necessity.
And when you anyway build a big and heavy concrete building, a sealing wall around them weights nothing compared to the structure total mass.

6 hours ago, softweir said:

There'd be no winds or rain, so no need for heavy walls, windows or roofs,

If a building is under gtound, it can get a stone rain on its roof. Or a 100x100x100 m stone block which suddenly decided to fall, making a new lava tube entrance. The ground is not a monolith.
Building a building on surface, you have you either 2 m thick reinforced concrete roof, or 2 m thick regolith coat. Both of them cannot fall.

[daniel l.]

Anyone got a big glass cork? That cave could be capped off and pressurized.

[cubinator]

17 hours ago, daniel l. said:

Anyone got a big glass cork? That cave could be capped off and pressurized.

It would take millions of tons of air to pressurize the entire cave. Not feasible at this point, even with BFR.

Edited October 26, 2017 by cubinator

[daniel l.]

2 hours ago, cubinator said:

It would take millions of tons of air to pressurize the entire cave. Not feasible at this point, even with BFR.

Sure. But it would be a perfect long-run goal.

And hey! Maybe there's ice down there that we can get oxygen from. Such a cave would provide great amounts of shade, allowing deposits of ice to exist.

[PB666]

46 minutes ago, daniel l. said:

Sure. But it would be a perfect long-run goal.

And hey! Maybe there's ice down there that we can get oxygen from. Such a cave would provide great amounts of shade, allowing deposits of ice to exist.

No  it wouldn't, the cave system is likely cracked and has buried tubes going to the surface. YOU would put air in and it would either leak out or blow-up at somepoint with the stress fractures finally give.

Use the Anglo-Roman philosphophy of divide an conquer. Don't bite of more than you can chew, certainly not more than the resulting xxxx pile would cover your head (as in caveins and blowing of precious little colonist into the vacuum of space)

 

[daniel l.]

Just now, PB666 said:

No  it wouldn't, the cave system is likely cracked and has buried tubes going to the surface. YOU would put air in and it would either leak out or blow-up at somepoint with the stress fractures finally give.

Use the Anglo-Roman philosphophy of divide an conquer. Don't bite of more than you can chew, certainly not more than the resulting xxxx pile would cover your head (as in caveins and blowing of precious little colonist into the vacuum of space)

 

Still, despite the flaws, those walls would make a starting point. Fill in the cracks with resin, and cover it all over with perhaps a spray-on sealant that could be made from local materials.

In all, such an endeavor might cost only a couple hundred million. It could be done almost entirely by robots.