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Considering the:

  • required reflectivity and insulation from heat from a star,
  • heat dissipation capability (radiators, other methods),
  • general conductivity of the skin,

of a modern spacecraft e.g. ISS, other planned craft, how well would a life support system designed for a space craft operate on a planet? I'm mainly considering extreme Earth conditions e.g. polar environment or extreme desert heat.

For example, would a system perform better due to the temperatures being less extreme in such conditions, or would they perform worse due to reduced heat dissipation capability and the presence of thermal conductivity through skin contact with air/land?

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  • $\begingroup$ Sorry, I was just thinking regarding the main points that I mentioned. $\endgroup$ Jun 25, 2023 at 8:53
  • $\begingroup$ I'm wondering why this question isn't getting more answers... surely it's simple enough? $\endgroup$ Jun 26, 2023 at 8:59

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Environmental conditions in space are extremely unlike environmental conditions on Earth, or on any planet with a significant atmosphere.

First, let us consider the small issue of gravitation, which may or may not have been taken into account when designing the spacecraft. For example, a spacecraft such as the ISS, which was always intended to operate on orbit and only on orbit, simply does not have the structural strength to sustain its own weight on the surface of Earth. But let's put this aside, because a spacecraft can be designed to be strong enough to operate on the surface of a planet.

Second, vacuum is a most excellent thermal insulator. Spacecraft designed to operate on Earth orbit, where the sun provides one and a half kilowatts of energy per square meter of spacecraft, need to employ ginormous radiators to avoid roasting the crew; in the vacuum of space, heat can only be dissipated by radiating it away as thermal infrared. The entire cooling subsystem would be completely useless on the surface of Earth, where we can use a much smaller radiator to dump excess heat into the atmosphere using convective cooling.

On the other hand, heating up the spacecraft is much less of an issue in the vacuum of space, where the surrounding environment is a thermal insulator, than in such nice places as the Antarctic or the deep ocean, where the surrounding environment is eager to suck off all the heat.

Overall, the basic idea is that life support systems are designed for the environment where they are intended to operate, and will function poorly if at all in a massively different environment. The life support system of a nuclear-powered submarine, which is perfectly able to keep a hundred people alive and well hundreds of meters under water for many months, would not works at all in space. The life support system of ISS, which is perfectly able to keep the crew alive and well for many months in space, would not work at all under water; on the surface, for example in the Sahara, it might work for some time, but it would be the wrong solution, because a simpler system would be sufficient.

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Yes and No.

What do I mean? Well it depends on your definition of Practical.

Would a system designed for the hostility of Space work on a planet? In the majority of cases, yes.

In that sense, it's Practical.

However, if we consider the additional challenges of Space that don't exist on a planet and that the system is having to expend extra resources or is requiring additional space for the modules that are now providing superfluous functionality - then it that sense, No, it's not Practical.

If it's a choice between jury-rigging a Space system onto a planet, because that's your only option (as far as the story goes) then, yeah, it's Practical.

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  • $\begingroup$ In short, it is usable, but a bit of an overkill $\endgroup$
    – Negdo
    Jun 26, 2023 at 9:31
  • $\begingroup$ Not all extremes on earth... Space Ships make poor submarines and vice versa. But most terrestrial extremes (hottest atmospheric temperatures, coldest atmospheric temperatures.) Most habitat spaces are designed on earth to begin with, after all. $\endgroup$
    – hszmv
    Jun 26, 2023 at 18:15
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Let's consider a few things.

  1. Life support means lights. Those are useful on the surface.

  2. Life support means toilets and wastewater disposal. Those are designed for zero-G, not a gravity well, so they're unlikely to work. If they do work, they'll be uncomfortable if not impractical.

  3. Space stations have heaters, not cooling systems, which means they're OK for cold areas (arctic) but not hot areas (equator). Rough guess? Use the Tropics of Cancer and Capricorn as "useful outside but not inside" limits.

@AlexP correctly points out that the ISS has massive heat radiators. However, those radiators are designed for zero-G and not a gravity well with weather. Let's ignore all that. Those radiators will work best in cold weather, so my assertion about the tropics IMO still stands.

  1. Space stations are designed to keep pressure in, not out, so they might have trouble with hull integrity. Usually the pressure inside and outside a construction on the surface is identical(ish), so no problem. It's when a storm blows in you might have trouble.

  2. Worse, space stations are designed for zero-G, not surface gravity. It may be true that a particular orientation of the habitat could result in the structure not collapsing, but you're still going to run into the fact that the placement of beds, tables, cabinets, etc., expect zero-G. Regardless the orientation, there's substantial portions of the station that would be all-but (if not completely) useless.

  3. Whatever shielding is used to keep radiation away from astronauts in orbit is pretty much dead weight onthe surface, unless you're planning to use this in the wake of a nuclear explosion.

  4. Lifesupport for a space station like the ISS have limited storage for food — and what storage it has is primarily for space-based supplies. Fresh food storage is very limited. Bread other than tortillas are verboten. Said another way, using a space station on the surface will require very regular food and maintenance deliveries or access to food outside and a fire pit (since NASA no likey fire in their stuff).

Conclusion

  • Believable? given the right story considerations.
  • Practical? probably not.
  • Long-term? No.
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  • $\begingroup$ Hmmm, as far as I know cooling the ISS is a real problem, whereas heating it up is non-issue. It is easy to heat up the interior of the ISS -- the thousands of watts of thermal waste power generated by the crew and the machinery are more than enough. On the other hand, rejecting those thousands of watts so that they don't accumulate is a real challenge. (The fanfold-like structures are biggg radiators.) $\endgroup$
    – AlexP
    Jun 26, 2023 at 20:25
  • $\begingroup$ @AlexP That's a good point... How effective would those massive radiators be in an atmosphere? Other than they'd be a pain to keep in place undamaged. $\endgroup$
    – JBH
    Jun 26, 2023 at 20:31
  • $\begingroup$ They would be completely ineffective, because they would collapse under their own weight, just like most of the rest of the ISS. If propped up somehow (and arranged so that they don't face the ground) they would probably work fine, provided the pumps which circulate the coolant are beefed up to deal with operating at 1 g instead of 0 g. On the other hand, they would be utterly completely useless, because using air cooling (like an ordinary car radiator) would be about a thousand times easier. $\endgroup$
    – AlexP
    Jun 26, 2023 at 20:35
  • $\begingroup$ @AlexP Would you submit an answer expanding on your point? I think that's more what I'm looking for. JBH, thank you; would you be able to add anything about heat insulation and conductivity of the air/land? $\endgroup$ Jun 26, 2023 at 20:56
  • $\begingroup$ @AhmedTawfik Insulation is insulation. We use it in houses and spacecraft. Off-hand, I don't see how that's particularly relevant other than on a space station it's designed with the assumption that outside is always colder than inside. As for air/land conductivity - why are you asking about that? Spacecraft are designed like automobiles, to be electrically independent of their surroundings. $\endgroup$
    – JBH
    Jun 26, 2023 at 22:55
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Power could be an issue. The solar panels the ISS uses are calibrated for vacuum, which means they might not deliver enough power in atmo. Especially if they got dusty.

Heat might also be an issue. Vacuum's pretty insulative, so if the temperature outside is uncomfortable, the system might not be able to dump or retain heat as needed.

Those are the only problems I'd expect. Certainly both solvable with effort.

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