4 ms·

I guess there are a lot details not explained in the article and much of them have come up in the research. I would have liked a discussion over how this stuff

I guess there are a lot details not explained in the article and much of them have come up in the research. I would have liked a discussion over how this stuff could be produced on Mars, because no self-respecting rocket engineer would allow transplanetary shipping of a material largely composed of air.

russdill 7y ago
The primary components of Mars's crust are silicon and oxygen. The components of Silica Aerogel are .... silicon and oxygen.
- bayesian_horse 7y ago
  Thank you, I didn't know that. Though the next question is how much energy you need to part the silicon and the oxygen and bring them back together to form the aerogel.
  - jacobush 7y ago
    One nice thing which didn't automatically occur to me, is that a nuclear fission reactor on Mars would be comparatively cheap to build. You don't need any radiation shielding at all. Just walk away and turn it on. Have it produce methane and oxygen or electricity or both.
    - bayesian_horse 7y ago
      That would require really good automation. I think most nuclear reactors still require a lot of manual labor relatively close by. But yes, some kind of fission or fusion reactor would be on a colonization plan, if it is easier/cheaper than solar. One problem though would be getting fissile material. You can probably find some on Mars or its moons or some asteroids, but it would require lots of heavy industry to get enough of it for reactors. Bringing significant amounts of nuclear fuel from Earth would be really unpopular, what with the risk of rockets blowing up. That risk or fear is also what prohibits the use of nuclear propulsion for space travel...
      - jacobush 7y ago
        Yeah... politically it would be hard, I agree. But I don't think it would be a show stopper technically to bring fissile material from earth. For one, automated nuclear power plants are being designed for use on here on Earth. The fissile material itself does not weigh very much. It's also not (very) radioactive until you start the process. The bulk mass of a (normal) reactor is shielding and cooling plumbing. You don't need any shielding on Mars, and cooling could maybe (probably?) be some kind of radiator/convector to the surrounding air. Maybe you could even crack the CO2 with the heat directly? Fusion needs a lot plumbing and containment. Fission is just basically a pile of fissile material in proximity. Not very hard if you can skip on all the protection.
        stefco_ 7y ago
        You still need a heat sink of some sort to extract usable energy from any reactor, nuclear or otherwise; this is a universal property of engines [1]. Radiators are very inefficient for this and would be far heavier than the equivalent water cooling method. Same for air-cooling (especially in mars's thinner atmosphere). The cooling systems are not just there to prevent meltdowns; you need heat to flow, in large quantities, from a hot place to a cool place in order to extract energy. You're right that, if you could find some useful endothermic reaction like vaporizing CO2, you could use it as a heat sink. The problem is that distributing heat to arbitrary places in the martian ground (remember, this CO2 is not magically flowing to you) requires an even more complex heat exchanger than that used by a simple earth-based reactor. Not to mention that having no shielding would be hell for your robots; radiation hardening of automated systems remains non-trivial. But the fundamental thermodynamics strike me as harder. Maybe there are niches where this would make sense, but the thermodynamics is the elephant in the room. [1] https://en.wikipedia.org/wiki/Thermal_efficiency https://en.wikipedia.org/wiki/Thermal_efficiency
        jacobush 7y ago
        Actually, the CO2 is flowing, it's in the atmosphere. :) But maybe it's not enough.
memorysafety 7y ago
If you ever heard of "liquid glass", or silica glue -- it's the same kind of material as in airogel, a mix of (hydrated) silicate minerals. The main trick in making aerogel is drying it out, in a way when the liquid doesn't collapse the porous structure by its surface tension. Peeps on youtube usually do this through a "supercritical CO₂" process -- which basically avoids having any liquid surface. That said, manufacturing aerogel on Mars seems way more feasible than transporting it.

russdill 7y ago

The primary components of Mars's crust are silicon and oxygen. The components of Silica Aerogel are .... silicon and oxygen.

bayesian_horse 7y ago
Thank you, I didn't know that. Though the next question is how much energy you need to part the silicon and the oxygen and bring them back together to form the aerogel.
- jacobush 7y ago
  One nice thing which didn't automatically occur to me, is that a nuclear fission reactor on Mars would be comparatively cheap to build. You don't need any radiation shielding at all. Just walk away and turn it on. Have it produce methane and oxygen or electricity or both.
  - bayesian_horse 7y ago
    That would require really good automation. I think most nuclear reactors still require a lot of manual labor relatively close by. But yes, some kind of fission or fusion reactor would be on a colonization plan, if it is easier/cheaper than solar. One problem though would be getting fissile material. You can probably find some on Mars or its moons or some asteroids, but it would require lots of heavy industry to get enough of it for reactors. Bringing significant amounts of nuclear fuel from Earth would be really unpopular, what with the risk of rockets blowing up. That risk or fear is also what prohibits the use of nuclear propulsion for space travel...
    - jacobush 7y ago
      Yeah... politically it would be hard, I agree. But I don't think it would be a show stopper technically to bring fissile material from earth. For one, automated nuclear power plants are being designed for use on here on Earth. The fissile material itself does not weigh very much. It's also not (very) radioactive until you start the process. The bulk mass of a (normal) reactor is shielding and cooling plumbing. You don't need any shielding on Mars, and cooling could maybe (probably?) be some kind of radiator/convector to the surrounding air. Maybe you could even crack the CO2 with the heat directly? Fusion needs a lot plumbing and containment. Fission is just basically a pile of fissile material in proximity. Not very hard if you can skip on all the protection.
      - stefco_ 7y ago
        You still need a heat sink of some sort to extract usable energy from any reactor, nuclear or otherwise; this is a universal property of engines [1]. Radiators are very inefficient for this and would be far heavier than the equivalent water cooling method. Same for air-cooling (especially in mars's thinner atmosphere). The cooling systems are not just there to prevent meltdowns; you need heat to flow, in large quantities, from a hot place to a cool place in order to extract energy. You're right that, if you could find some useful endothermic reaction like vaporizing CO2, you could use it as a heat sink. The problem is that distributing heat to arbitrary places in the martian ground (remember, this CO2 is not magically flowing to you) requires an even more complex heat exchanger than that used by a simple earth-based reactor. Not to mention that having no shielding would be hell for your robots; radiation hardening of automated systems remains non-trivial. But the fundamental thermodynamics strike me as harder. Maybe there are niches where this would make sense, but the thermodynamics is the elephant in the room. [1] https://en.wikipedia.org/wiki/Thermal_efficiency https://en.wikipedia.org/wiki/Thermal_efficiency
        jacobush 7y ago
        Actually, the CO2 is flowing, it's in the atmosphere. :) But maybe it's not enough.

memorysafety 7y ago

If you ever heard of "liquid glass", or silica glue -- it's the same kind of material as in airogel, a mix of (hydrated) silicate minerals. The main trick in making aerogel is drying it out, in a way when the liquid doesn't collapse the porous structure by its surface tension. Peeps on youtube usually do this through a "supercritical CO₂" process -- which basically avoids having any liquid surface. That said, manufacturing aerogel on Mars seems way more feasible than transporting it.