6 ms·

There is the small detail of heating the regolith to 1400c. It's not very clear where that energy comes from (at least not at scale). Burning fuels seems to be

There is the small detail of heating the regolith to 1400c. It's not very clear where that energy comes from (at least not at scale). Burning fuels seems to be out. So I guess nuclear or solar? Mars solar is weaker than earth, but I guess let's of panels plus lots of batteries could work. Sorta. Not sure it produces "tons" of material very quickly. Nuclear is the other option. But would rely on fuel from earth. Not to mention that building a reactor big enough to sustain a colony, plus industry, would be challenging. And of course landing fresh uranium on Mars would be risky. (It's heavy, and any accident would render a chunk of Mars radioactive for quite some time.) Oh, and the reactor would need to be air-cooled not water-cooled. But, I guess, yay regolith?

strken 1y ago
Can't you eventually mine and enrich uranium on Mars itself?
- bruce511 1y ago
  It's possible, although unlikely, that there are mineable deposits of uranium on Mars. There are trace amounts, but its unlikely that minable deposits formed.
  - chii 1y ago
    why is there unlikely to be mine-able uranium deposits? It's not like there's some geological process on mars that strips it away (presumably).
    - MangoToupe 1y ago
      I think the implication is that uranium likely exists in low density and cannot be easily extracted without a great deal of chemical processing and disposal of waste product (rather than deposits of uranium a la natural reactors: https://en.m.wikipedia.org/wiki/Natural_nuclear_fission_reactor https://en.m.wikipedia.org/wiki/Natural_nuclear_fission_reac...)
    - strken 1y ago
      I'm not an expert, but I was under the impression that while water is often involved in forming deposits of uranium ores, they can also form because of volcanic activity alone. Maybe bruce511 thinks such deposits are likely to be rare, or maybe I'm wrong.
    - throwup238 1y ago
      The geological processes, which Mars lacks, are supposed to concentrate uranium, not strip it away. The actual geochemical explanation is complicated but long story short Mars is a geologically dead planet without much water that doesn’t like to form rock that can hold uranium ore. Uranium concentrates in felsic (high silica) rock which forms under crustal recycling on Earth - the heat at the interface between the crust and mantle allows the Fe-Mg to strip away. Water dissolving uranium then injects into the felsic rock, the uranium precipitates out, and the rock later gets pushed up higher into the crust. Mars has neither the active geology nor seemingly enough water to allow much felsic rock to form. Satellite surveys show the surface is covered with mostly basaltic rock (low silica, high Fe-Mg) with very small pockets of felsic. The processes that form these pockets are largely unlike those formed on Earth and don’t have the same geochemistry, especially without ample water.
      - HPsquared 1y ago
        It's amazing how many natural processes we have on Earth that work in our favour.
      - pomian 1y ago
        I just replaced my screen background with a photo from Mars with a big granitic(?)/ granodiorite(?) Boulder, surrounded by volcanic rocks. It is an amazing quandary! Fun to look at, and think - ok, how was this made!? To simplify: the Boulder: is a white rock with black crystals, whereas all the surrounding rocks are dark grey or black(look like lava.) The Boulder is somewhat round(let's say 1 meter across +-100%), has been broken at some of the edges, and rounded at others. How was it broken? Rounded, and the fact it isn't in the Chevy place judging by the surrounding rocks, HOW, did it get there? So we are looking at various igneous processes at work here. Deep and surface. Plus, transport, by water? Ice? Liquid CO2? Unknown. https://www.goodnewsnetwork.org/wp-content/uploads/2024/06/Perseverance-rover-spies-white-rock-Atoko-Point-on-Mars-boulder-field-NASA-Western-Washington-University.jpg https://www.goodnewsnetwork.org/wp-content/uploads/2024/06/P...
owenversteeg 1y ago
Nuclear and solar are actually pretty competitive here at MW scale, optimistic projections for both are in the ballpark of 100 tons per MW including associated power electronics. That's to say, if Starship continues on the trajectory it's on, putting aside a few MW on Mars to operate a smelter is within the realm of possibility. On a larger scale (GW) the answer is likely nuclear, unless we can come up with a realistic way to produce solar panels on Mars. Mass-wise, nuclear scales very well, but solar is nearly linear. There's also some possibility we come up with a creative way to produce methane or another fuel.
- bruce511 1y ago
  Solar is likely what will power anything we put there, in the short term at least. But Mars only gets 43% of the solar energy that earth gets. So you need at least twice the panels. Not to mention the batteries. This is fine for "residential", but perhaps not suited to industrial scale. Yes, I expect nuclear is the best choice of a list of 1, but it will be substantially harder to build one on Mars than here. For starters the lack of water, and the lack of atmosphere density would result in substantial cooling challenges. However you slice it, energy on Mars is completely dependent on earth. Panels, batteries, uranium- none of it can be made on Mars, and all have "short" lifespans.
  - chii 1y ago
    > the lack of atmosphere density would result in substantial cooling challenges. heat exchange(s) such that the human settlement(s) are warmed by this "waste" heat? Mars is cold, and likely need to have many pipes to generate heat for human settlement, so why not build it in via this need?
    - bruce511 1y ago
      Sure, Mars is really cold, so it's natural that this waste heat would be used constructively. There are communities in the Artic circle that do this. But that's not really the challenge I was referring to. The problem is less "where should the heat go" and more the medium of transport. A closed cycle, pressurized water cooling would likely be used. That has it's own problems, but there's no local water source, and steam , while a possibility, has even more challenges. Indeed current nuclear uses a steam-turbine cycle for actual generation, and that likely wouldn't work on Mars either. So the nuclear reactor there would be novel in lots of ways. Ultimately though it will generate more waste heat than a colony can use, and getting rid of the rest in a thin Martian atmosphere (that's also dusty) will be difficult.
stevage 1y ago
Could always build a helioplex - a gigantic solar concentrator.
metalman 1y ago
cooling can be done with radiators pointed north, into the permanently black sky,with essentialy no convective heat gain or loss, build for noon in mid summer, and forget about it lots of things work on mars that dont work here, Thin film prevoskerite solar ,which is sensitive to water and oxygen and therefor difficult here, can be sprayed on whatever is handy on mars(oversimplification, but), and the same goes for a smelter that is electric, where one of the byproducts is oxygen driven off, hand that, and that high quality metal and castings will be possible as the lack of atmospheric oxygen and low pressure will de gass metals, also metals wont corode after bieng made. given the very low night time temperatures, it should be quite easy to liquify martian "air" and use it for day time cooling where needed and also the exraction of trace gasses other than CO², which is the bulk. none of that maters without a good supply of water to crack for fuel and air and general living, and as there is a whole world to work with, it is likely that there are a few areas that will have a fortuitous convergence of ALL the things possible, in one spot, kind of like early settlers finding a stand of trees, felled by beavers, bark stripped and pre notched for assembly into a cabin, next to a pond with fish and medows all around to put things in perspective pure gold would be good for use as sheet metal, as it's ductility and ease of refinement would make it the cheapest alternative it's doable, but only just, and only if we get our shit together and decide that an impossible, ultra long term project to become an interplanitary species is a better way to use our excess capacity than whatever the fuck it is we are doing now
HPsquared 1y ago
Cooling a large nuclear power reactor would be a challenge on Mars. Probably you'd want something compact that runs at high temperature, like a molten salt design, to make heat rejection easier. Edit: side benefit would be you could use the heat directly for processes like this metallurgy thing.
- ainiriand 1y ago
  Cooling is should not be an issue, considering it goes to ~-80C at night, we only need a smart way of harnessing that difference.
  - IsTom 1y ago
    Mars atmosphere is so thin that it won't really help to cool down a reactor.
  - fuoqi 1y ago
    No, it absolutely will be an issue. You need to dispose of ~100 MW of heat energy. Simply dumping it into ground will quickly heat it up, you can't rely on water evaporation for obvious reasons, same goes for convection because of the thin atmosphere. So your only option is radiative cooling, either by using ground or dedicated radiators. But because it's relatively inefficient, you will need a lot of area and materials for it.
    - HPsquared 1y ago
      High-temperature reactor designs are essential. Radiative heat transfer scales with temperature to the fourth power. So if you reject 100 MW of waste heat at, say, 400°C (750°F), a radiative heat transfer area of 10,000 m^2 (i.e. 100m x 100m square) would be sufficient. That's quite big and hot, but 100 MW is a lot! Radiative heat rejection at 100°C would require 10x as much area.
      - fuoqi 1y ago
        Disposing heat at a higher temperature would also mean that you need to dispose of more heat (~2x in the case of 400°C vs sub-100°C) and losing energy which could've been used for useful work such as generating electricity. It may be reasonable to do at early stages, but after the colony is able to produce metals in situ it would be better to build more radiators. Especially considering that you also need to dispose latent heat from other sources.
fuoqi 1y ago
>It's heavy, and any accident would render a chunk of Mars radioactive for quite some time. Do you think that nuclear fuel is some kind of green glowing stuff like in Simpsons? New nuclear pellets is just a bunch of uranium dioxide, which is mildly alpha radioactive. In other words, as long as you are not inhaling its dust, it's more or less safe to handle even with bare hands. Even the worst possible kind of accident is likely to be absolutely irrelevant from the radiation safety point of view considering high levels of natural solar radiation on the surface of Mars.
- moralestapia 1y ago
  Heating stuff to 1,400C is also a solved problem, but he seems to be unaware of that as well. The guy's clearly not the sharpest tool for this ...
kaliqt 1y ago
Small reactors have been done by NASA, among many other organizations, for decades. Also uranium is not as radioactive or lethal as you'd think in this case. It can be sent there safely and without issue. Also reactors can be MSR (molten salt reactor) greatly reducing water needs.
jerf 1y ago
"It's heavy, and any accident would render a chunk of Mars radioactive for quite some time." If you model the rest of the universe out of Earth's highly protective environment as "already being the result of a major nuclear accident", you're not actually that far off. The people evacuated from Chernobyl received about 33 milli-Sieverts of radiation [1]. The surface of the moon gets about 60 micro-Sieverts of radiation per hour[2]... or, in other words, being on the surface of the moon for 20 days is the rough equivalent of experiencing one Chernobyl disaster. This is just a rough estimate for intuition purposes, it's not exactly the same radiation in both cases, but it's close enough to make the point. This page [3] says the surface of Mars is about .7 milli-Sieverts of radiation per day, for about 30 micro-Sieverts per hour (to use the same units as the moon above), which is about right for the inverse-square and slows the exposure to one Chernobyl per 40 days. And by universal standards, that's still rather low radiation. There's entire galactic clusters with the central blackholes blasting sterilizing amounts of radiation out into their entire cluster. Earth is fairly special; a good reason not to mess it up. The "jump to Mars plan" is perhaps not impossible but it's really, really, really hard. [1]: https://nuclear-energy.net/nuclear-accidents/chernobyl/chernobyl-radiation https://nuclear-energy.net/nuclear-accidents/chernobyl/chern... [2]: https://www.space.com/moon-radiation-dose-for-astronauts-measured https://www.space.com/moon-radiation-dose-for-astronauts-mea... [3]: https://spacemath.gsfc.nasa.gov/planets/10Page74.pdf https://spacemath.gsfc.nasa.gov/planets/10Page74.pdf
LargoLasskhyfv 1y ago
I've read some parts of Mars are full of Thorium, sometimes, somewhere. Calls for in-situ-utilization, doesn't it?

strken 1y ago

Can't you eventually mine and enrich uranium on Mars itself?

bruce511 1y ago
It's possible, although unlikely, that there are mineable deposits of uranium on Mars. There are trace amounts, but its unlikely that minable deposits formed.
- chii 1y ago
  why is there unlikely to be mine-able uranium deposits? It's not like there's some geological process on mars that strips it away (presumably).
  - MangoToupe 1y ago
    I think the implication is that uranium likely exists in low density and cannot be easily extracted without a great deal of chemical processing and disposal of waste product (rather than deposits of uranium a la natural reactors: https://en.m.wikipedia.org/wiki/Natural_nuclear_fission_reactor https://en.m.wikipedia.org/wiki/Natural_nuclear_fission_reac...)
  - strken 1y ago
    I'm not an expert, but I was under the impression that while water is often involved in forming deposits of uranium ores, they can also form because of volcanic activity alone. Maybe bruce511 thinks such deposits are likely to be rare, or maybe I'm wrong.
  - throwup238 1y ago
    The geological processes, which Mars lacks, are supposed to concentrate uranium, not strip it away. The actual geochemical explanation is complicated but long story short Mars is a geologically dead planet without much water that doesn’t like to form rock that can hold uranium ore. Uranium concentrates in felsic (high silica) rock which forms under crustal recycling on Earth - the heat at the interface between the crust and mantle allows the Fe-Mg to strip away. Water dissolving uranium then injects into the felsic rock, the uranium precipitates out, and the rock later gets pushed up higher into the crust. Mars has neither the active geology nor seemingly enough water to allow much felsic rock to form. Satellite surveys show the surface is covered with mostly basaltic rock (low silica, high Fe-Mg) with very small pockets of felsic. The processes that form these pockets are largely unlike those formed on Earth and don’t have the same geochemistry, especially without ample water.
    - HPsquared 1y ago
      It's amazing how many natural processes we have on Earth that work in our favour.
    - pomian 1y ago
      I just replaced my screen background with a photo from Mars with a big granitic(?)/ granodiorite(?) Boulder, surrounded by volcanic rocks. It is an amazing quandary! Fun to look at, and think - ok, how was this made!? To simplify: the Boulder: is a white rock with black crystals, whereas all the surrounding rocks are dark grey or black(look like lava.) The Boulder is somewhat round(let's say 1 meter across +-100%), has been broken at some of the edges, and rounded at others. How was it broken? Rounded, and the fact it isn't in the Chevy place judging by the surrounding rocks, HOW, did it get there? So we are looking at various igneous processes at work here. Deep and surface. Plus, transport, by water? Ice? Liquid CO2? Unknown. https://www.goodnewsnetwork.org/wp-content/uploads/2024/06/Perseverance-rover-spies-white-rock-Atoko-Point-on-Mars-boulder-field-NASA-Western-Washington-University.jpg https://www.goodnewsnetwork.org/wp-content/uploads/2024/06/P...

owenversteeg 1y ago

Nuclear and solar are actually pretty competitive here at MW scale, optimistic projections for both are in the ballpark of 100 tons per MW including associated power electronics. That's to say, if Starship continues on the trajectory it's on, putting aside a few MW on Mars to operate a smelter is within the realm of possibility. On a larger scale (GW) the answer is likely nuclear, unless we can come up with a realistic way to produce solar panels on Mars. Mass-wise, nuclear scales very well, but solar is nearly linear. There's also some possibility we come up with a creative way to produce methane or another fuel.

bruce511 1y ago
Solar is likely what will power anything we put there, in the short term at least. But Mars only gets 43% of the solar energy that earth gets. So you need at least twice the panels. Not to mention the batteries. This is fine for "residential", but perhaps not suited to industrial scale. Yes, I expect nuclear is the best choice of a list of 1, but it will be substantially harder to build one on Mars than here. For starters the lack of water, and the lack of atmosphere density would result in substantial cooling challenges. However you slice it, energy on Mars is completely dependent on earth. Panels, batteries, uranium- none of it can be made on Mars, and all have "short" lifespans.
- chii 1y ago
  > the lack of atmosphere density would result in substantial cooling challenges. heat exchange(s) such that the human settlement(s) are warmed by this "waste" heat? Mars is cold, and likely need to have many pipes to generate heat for human settlement, so why not build it in via this need?
  - bruce511 1y ago
    Sure, Mars is really cold, so it's natural that this waste heat would be used constructively. There are communities in the Artic circle that do this. But that's not really the challenge I was referring to. The problem is less "where should the heat go" and more the medium of transport. A closed cycle, pressurized water cooling would likely be used. That has it's own problems, but there's no local water source, and steam , while a possibility, has even more challenges. Indeed current nuclear uses a steam-turbine cycle for actual generation, and that likely wouldn't work on Mars either. So the nuclear reactor there would be novel in lots of ways. Ultimately though it will generate more waste heat than a colony can use, and getting rid of the rest in a thin Martian atmosphere (that's also dusty) will be difficult.

stevage 1y ago

Could always build a helioplex - a gigantic solar concentrator.

metalman 1y ago

cooling can be done with radiators pointed north, into the permanently black sky,with essentialy no convective heat gain or loss, build for noon in mid summer, and forget about it lots of things work on mars that dont work here, Thin film prevoskerite solar ,which is sensitive to water and oxygen and therefor difficult here, can be sprayed on whatever is handy on mars(oversimplification, but), and the same goes for a smelter that is electric, where one of the byproducts is oxygen driven off, hand that, and that high quality metal and castings will be possible as the lack of atmospheric oxygen and low pressure will de gass metals, also metals wont corode after bieng made. given the very low night time temperatures, it should be quite easy to liquify martian "air" and use it for day time cooling where needed and also the exraction of trace gasses other than CO², which is the bulk. none of that maters without a good supply of water to crack for fuel and air and general living, and as there is a whole world to work with, it is likely that there are a few areas that will have a fortuitous convergence of ALL the things possible, in one spot, kind of like early settlers finding a stand of trees, felled by beavers, bark stripped and pre notched for assembly into a cabin, next to a pond with fish and medows all around to put things in perspective pure gold would be good for use as sheet metal, as it's ductility and ease of refinement would make it the cheapest alternative it's doable, but only just, and only if we get our shit together and decide that an impossible, ultra long term project to become an interplanitary species is a better way to use our excess capacity than whatever the fuck it is we are doing now

HPsquared 1y ago

Cooling a large nuclear power reactor would be a challenge on Mars. Probably you'd want something compact that runs at high temperature, like a molten salt design, to make heat rejection easier. Edit: side benefit would be you could use the heat directly for processes like this metallurgy thing.

ainiriand 1y ago
Cooling is should not be an issue, considering it goes to ~-80C at night, we only need a smart way of harnessing that difference.
- IsTom 1y ago
  Mars atmosphere is so thin that it won't really help to cool down a reactor.
- fuoqi 1y ago
  No, it absolutely will be an issue. You need to dispose of ~100 MW of heat energy. Simply dumping it into ground will quickly heat it up, you can't rely on water evaporation for obvious reasons, same goes for convection because of the thin atmosphere. So your only option is radiative cooling, either by using ground or dedicated radiators. But because it's relatively inefficient, you will need a lot of area and materials for it.
  - HPsquared 1y ago
    High-temperature reactor designs are essential. Radiative heat transfer scales with temperature to the fourth power. So if you reject 100 MW of waste heat at, say, 400°C (750°F), a radiative heat transfer area of 10,000 m^2 (i.e. 100m x 100m square) would be sufficient. That's quite big and hot, but 100 MW is a lot! Radiative heat rejection at 100°C would require 10x as much area.
    - fuoqi 1y ago
      Disposing heat at a higher temperature would also mean that you need to dispose of more heat (~2x in the case of 400°C vs sub-100°C) and losing energy which could've been used for useful work such as generating electricity. It may be reasonable to do at early stages, but after the colony is able to produce metals in situ it would be better to build more radiators. Especially considering that you also need to dispose latent heat from other sources.

fuoqi 1y ago

>It's heavy, and any accident would render a chunk of Mars radioactive for quite some time. Do you think that nuclear fuel is some kind of green glowing stuff like in Simpsons? New nuclear pellets is just a bunch of uranium dioxide, which is mildly alpha radioactive. In other words, as long as you are not inhaling its dust, it's more or less safe to handle even with bare hands. Even the worst possible kind of accident is likely to be absolutely irrelevant from the radiation safety point of view considering high levels of natural solar radiation on the surface of Mars.

moralestapia 1y ago
Heating stuff to 1,400C is also a solved problem, but he seems to be unaware of that as well. The guy's clearly not the sharpest tool for this ...

kaliqt 1y ago

Small reactors have been done by NASA, among many other organizations, for decades. Also uranium is not as radioactive or lethal as you'd think in this case. It can be sent there safely and without issue. Also reactors can be MSR (molten salt reactor) greatly reducing water needs.

jerf 1y ago

"It's heavy, and any accident would render a chunk of Mars radioactive for quite some time." If you model the rest of the universe out of Earth's highly protective environment as "already being the result of a major nuclear accident", you're not actually that far off. The people evacuated from Chernobyl received about 33 milli-Sieverts of radiation [1]. The surface of the moon gets about 60 micro-Sieverts of radiation per hour[2]... or, in other words, being on the surface of the moon for 20 days is the rough equivalent of experiencing one Chernobyl disaster. This is just a rough estimate for intuition purposes, it's not exactly the same radiation in both cases, but it's close enough to make the point. This page [3] says the surface of Mars is about .7 milli-Sieverts of radiation per day, for about 30 micro-Sieverts per hour (to use the same units as the moon above), which is about right for the inverse-square and slows the exposure to one Chernobyl per 40 days. And by universal standards, that's still rather low radiation. There's entire galactic clusters with the central blackholes blasting sterilizing amounts of radiation out into their entire cluster. Earth is fairly special; a good reason not to mess it up. The "jump to Mars plan" is perhaps not impossible but it's really, really, really hard. [1]: https://nuclear-energy.net/nuclear-accidents/chernobyl/chernobyl-radiation https://nuclear-energy.net/nuclear-accidents/chernobyl/chern... [2]: https://www.space.com/moon-radiation-dose-for-astronauts-measured https://www.space.com/moon-radiation-dose-for-astronauts-mea... [3]: https://spacemath.gsfc.nasa.gov/planets/10Page74.pdf https://spacemath.gsfc.nasa.gov/planets/10Page74.pdf

LargoLasskhyfv 1y ago

I've read some parts of Mars are full of Thorium, sometimes, somewhere. Calls for in-situ-utilization, doesn't it?