4 ms·

Just curious, I get low gravity, extreme temperature and flying debris, what are the physical challenges of building infrastructure on the moon? For example, I

by aynyc 4y ago

Just curious, I get low gravity, extreme temperature and flying debris, what are the physical challenges of building infrastructure on the moon? For example, I assume we are probably use local material to build stuff. What can we get from the moon or do we need to ship the whole thing there?

vkou 4y ago
> What can we get from the moon Similar to what we can get from the Earth (The mineral composition of the two bodies is similar), with the key difference being that terrestrial construction sites don't turn undifferentiated piles of rocks into buildings, doors, windows, elevators, and roadways. There's a colossal supply chain that turns those piles of rocks into usable building materials. We're likely to see moon roads sometime after we get flying cars, and economically viable fusion energy.
- tyingq 4y ago
  Interesting paper on making concrete on the moon: https://adsabs.harvard.edu/full/1985lbsa.conf..381L https://adsabs.harvard.edu/full/1985lbsa.conf..381L
  - adrian_b 4y ago
    That paper is not careful about the meaning of the used words and it does not discuss any of the difficult parts. "Concrete" normally refers to rocks that are bound with cement, without having to use high temperature and/or pressure. The paper does not explain how such a cement could be made from lunar rocks. The Portland cement and most other usual cements, which are used on Earth, require water, which is not available in most places on the Moon. What could be done is to extract the calcium oxide (quicklime), or other similar oxides, e.g. magnesia or yttria, from the lunar rocks. Without water, these oxides cannot be used to make cement, i.e. a binder that becomes solid without applying high temperature or pressure, but due to chemical reactions at low temperature. Nevertheless, these oxides can be used as binders in making ceramics, by sintering at a high temperature and moderate pressure, like making bricks on Earth. Thus one can make ceramics or glass on the Moon, which should be the cheapest materials, but not cement or concrete. There is no chance of making a building by pouring concrete, like on Earth. It should be possible to make a building from bricks, which might have shapes holding them together, but which must also use some metal parts, e.g. bolts or rivets, to ensure that they stay in place, in the absence of cement that could be applied like on Earth. It might be possible to seal the spaces between ceramic bricks with some kind of easily fusible glass, to make them airtight.
    - tyingq 4y ago
      There is a brief section called "Water Production".
      - adrian_b 4y ago
        That section can be safely ignored, because the proposed solution is not feasible, being based on non-lunar resources. Bringing hydrogen from Earth in quantities large enough to allow wasting it in construction materials, instead of using it only for making precious food and drinking water, for making water and acids used in certain chemical processes, for certain plastic materials used in small quantities and for fuel, is a completely impractical idea (this being a polite way of not calling such a solution for making construction materials on Moon as completely stupid). Hydrogen, nitrogen, carbon and sulfur will be the most expensive materials on the Moon, so they will be reserved for things where they are irreplaceable, not for construction materials, which are needed in huge quantities in comparison to the materials needed for any other application, so they must be made from the most abundant materials that can be found around.
- zardo 4y ago
  Isn't the moon going to be lacking in all sorts of minerals and ores that form in contact with a water?
nonameiguess 4y ago
Well, there is nothing organic on the moon, so you can't build with wood, don't have the oil and tar used in material like asphalt and roofing bases. There also isn't any oxygen for producing the fire that would be needed for smelting and what not. You need water for concrete. There is water on the moon, but it's not flowing or nearly as accessible as the water on Earth. It's largely bound up in ice at the poles. The moon is also lacking minerals that contain water as part of their own structure, like clay, which is a common construction material.
- djexjms 4y ago
  It is an interesting design problem for sure. I'm not expert on this stuff, but the first thing that comes to mind is gravel roads. Plenty of moon rocks would be available to be crushed into gravel. You might not even have to do that. Robots might be able to rake up enough material of suitable size. Once you have your gravel, use robots to make a path and compact the regolith. Put down the gravel over the compacted regolith, and there's your road. I have no idea if that would actually work or not, but it's interesting to think about.
  - polishdude20 4y ago
    Yeah and to compact it, you need more mass than on earth because gravity is lower. Or you somehow compact it between two pistons that can provide lots of force and not be limited by gravity.
    - Loughla 4y ago
      >Or you somehow compact it between two pistons that can provide lots of force and not be limited by gravity. I feel like maybe I'm missing something, but isn't this just a compactor? What am I missing? Does hydraulic pressure need gravity?
      - avmich 4y ago
        > Does hydraulic pressure need gravity? If your compaction includes application of force vertically, top down, you need something opposing that force. On the Earth it's usually gravity, and on the Moon it could be the same, just the gravity on the Moon is ~1/6 the Earth one.
balaji1 4y ago
IIUC you refer to "flying debris" from outer space hitting the surface of the moon. But the local lunar dust itself is a big challenge to be addressed for future moon mission EVAs: https://www.youtube.com/watch?v=0k9wIsKKgqo https://www.youtube.com/watch?v=0k9wIsKKgqo This dust would probably be a physical challenge to equipment used to build infra.

by aynyc 4y ago

vkou 4y ago

> What can we get from the moon Similar to what we can get from the Earth (The mineral composition of the two bodies is similar), with the key difference being that terrestrial construction sites don't turn undifferentiated piles of rocks into buildings, doors, windows, elevators, and roadways. There's a colossal supply chain that turns those piles of rocks into usable building materials. We're likely to see moon roads sometime after we get flying cars, and economically viable fusion energy.

tyingq 4y ago
Interesting paper on making concrete on the moon: https://adsabs.harvard.edu/full/1985lbsa.conf..381L https://adsabs.harvard.edu/full/1985lbsa.conf..381L
- adrian_b 4y ago
  That paper is not careful about the meaning of the used words and it does not discuss any of the difficult parts. "Concrete" normally refers to rocks that are bound with cement, without having to use high temperature and/or pressure. The paper does not explain how such a cement could be made from lunar rocks. The Portland cement and most other usual cements, which are used on Earth, require water, which is not available in most places on the Moon. What could be done is to extract the calcium oxide (quicklime), or other similar oxides, e.g. magnesia or yttria, from the lunar rocks. Without water, these oxides cannot be used to make cement, i.e. a binder that becomes solid without applying high temperature or pressure, but due to chemical reactions at low temperature. Nevertheless, these oxides can be used as binders in making ceramics, by sintering at a high temperature and moderate pressure, like making bricks on Earth. Thus one can make ceramics or glass on the Moon, which should be the cheapest materials, but not cement or concrete. There is no chance of making a building by pouring concrete, like on Earth. It should be possible to make a building from bricks, which might have shapes holding them together, but which must also use some metal parts, e.g. bolts or rivets, to ensure that they stay in place, in the absence of cement that could be applied like on Earth. It might be possible to seal the spaces between ceramic bricks with some kind of easily fusible glass, to make them airtight.
  - tyingq 4y ago
    There is a brief section called "Water Production".
    - adrian_b 4y ago
      That section can be safely ignored, because the proposed solution is not feasible, being based on non-lunar resources. Bringing hydrogen from Earth in quantities large enough to allow wasting it in construction materials, instead of using it only for making precious food and drinking water, for making water and acids used in certain chemical processes, for certain plastic materials used in small quantities and for fuel, is a completely impractical idea (this being a polite way of not calling such a solution for making construction materials on Moon as completely stupid). Hydrogen, nitrogen, carbon and sulfur will be the most expensive materials on the Moon, so they will be reserved for things where they are irreplaceable, not for construction materials, which are needed in huge quantities in comparison to the materials needed for any other application, so they must be made from the most abundant materials that can be found around.
zardo 4y ago
Isn't the moon going to be lacking in all sorts of minerals and ores that form in contact with a water?

nonameiguess 4y ago

Well, there is nothing organic on the moon, so you can't build with wood, don't have the oil and tar used in material like asphalt and roofing bases. There also isn't any oxygen for producing the fire that would be needed for smelting and what not. You need water for concrete. There is water on the moon, but it's not flowing or nearly as accessible as the water on Earth. It's largely bound up in ice at the poles. The moon is also lacking minerals that contain water as part of their own structure, like clay, which is a common construction material.

djexjms 4y ago
It is an interesting design problem for sure. I'm not expert on this stuff, but the first thing that comes to mind is gravel roads. Plenty of moon rocks would be available to be crushed into gravel. You might not even have to do that. Robots might be able to rake up enough material of suitable size. Once you have your gravel, use robots to make a path and compact the regolith. Put down the gravel over the compacted regolith, and there's your road. I have no idea if that would actually work or not, but it's interesting to think about.
- polishdude20 4y ago
  Yeah and to compact it, you need more mass than on earth because gravity is lower. Or you somehow compact it between two pistons that can provide lots of force and not be limited by gravity.
  - Loughla 4y ago
    >Or you somehow compact it between two pistons that can provide lots of force and not be limited by gravity. I feel like maybe I'm missing something, but isn't this just a compactor? What am I missing? Does hydraulic pressure need gravity?
    - avmich 4y ago
      > Does hydraulic pressure need gravity? If your compaction includes application of force vertically, top down, you need something opposing that force. On the Earth it's usually gravity, and on the Moon it could be the same, just the gravity on the Moon is ~1/6 the Earth one.

balaji1 4y ago

IIUC you refer to "flying debris" from outer space hitting the surface of the moon. But the local lunar dust itself is a big challenge to be addressed for future moon mission EVAs: https://www.youtube.com/watch?v=0k9wIsKKgqo https://www.youtube.com/watch?v=0k9wIsKKgqo This dust would probably be a physical challenge to equipment used to build infra.