Oh! Oh! I’ve thought about this!
It would make more sense to build habitat craters, dug deep enough into the ground that the surface air pressure would be at a level tolerable to humans (even if the atmosphere mixture was bad, being able to simply wear a respirator instead of an entire suit would be huge).
I did some math once, on Mars a crater several miles deep would have a pressure similar to Earth’s surface.
I think the Moon was like 40 miles or something, which at that point would probably run into other problems that I am not smart enough to worry about lol
That sounds like a really cool Sci Fi concept!
Like the inverse of doing Floating airship cities on Venus where the altitude 's atmosphere is earth equivalent
Edit: equivalent pressure wise, not necessarily component wise
Craters also have the added benefit of sheltering the occupants from radiation and falling debris that the non-existent atmosphere couldn’t protect from
Awesome answer but could you still answer the question for those still curious?
Well the craters could be domed off to maintain a healthy Earth-like atmosphere, and because the pressure is maintained by the depth of the crater the dome itself wouldn’t actually have to hold the air pressure in against a low pressure environment.
Also, presumably the reason a habitat would be planet-side is to take advantage of mineral resources, so a lot of digging will happen anyway.
You won’t even need to dig the hole! If you do this before much other habitations on the planet, you could precisely direct astroids to impact the same place to dig the whole for you. I think Cody’s Lab did a video about it, but I can’t find it right now.
Good odds there’s already a bunch of craters too, one of them will fit the bill
Getting closer to the core also means you get free heating.
Weren’t they doing this in The Expanse?
The low-gravity planets/moons we have access to have rather harsh radiation environments, too, so neither. Dig into the ground. You would put a bunker or dome up on the surface for observations and airlocks, but it’d be foolish to live that exposed on a surface without a deep well of atmosphere & Van Allen belts.
Renounce the sky; become mole people.
Just more proof that dwarves are the best humanoids.
Now I know next to nothing about it, but listening to the Art Bell Tape Vault and other alien/conspiracy theory/etc podcasts I know that one of the big theories popular amongst some in the UFO community is that the intelligence behind UFOs is some kind of breakaway civilization that survived one of the last cataclysms on Earth and kept advancing.
Low gravity planets are probably small planets with a low escape velocity, so they probably can’t hold a thick atmosphere. Domes are better at maintaining internal pressure.
Is gravity related to planet size? Wouldn’t density matter more?
If you take two planets of the same density, but one with a radius that’s twice as large, the mass and volume is going to be 8 times higher (2³), while the radius is only going to be twice as high.
The gravitational field is inversely proportional to the distance squared…
But escape velocity is only inversely proportional to the distance… This means that if you made a really dense, small planet where the surface gravity is identical to earth, it would still have a much lower escape velocity, so the gases are going to be likely to escape due to atmospheric escape; when a molecule is moving at a higher velocity than the escape velocity of the planet.
Thus, a smaller planet with the same surface gravity would lose it’s atmosphere due to atmospheric escape at a much higher rate than a larger planet.
You can take it the other way, and have a hypothetical megaplanet that has a lower density, but because of it’s enormous size, it still has an earth-like surface gravity, but it’s escape velocity could be so high that a hypothetical civilisation could be stuck there and might never be able to escape their planet’s gravitational binding energy, thus never becoming an interstellar civilization. In theory, a large enough black hole could have an event horizon where the acceleration is the same as on our planet’s surface, but the escape velocity would literally be the speed of light and people would never be able to leave.
First of all, domes in general aren’t a great idea except for maybe greenhouses - at least on planets in our system. NASA and ESA have done some cool concept experiments as to what pressurized architecture could look like, and it’s a lot more like a cross between a space station module and Earth architecture.
Second - assuming we’ve adapted/evolved to the low gravity, skyscrapers are probably the way to go. That said, if we’ve adapted that heavily we probably have similar adaptations to the atmosphere etc. - in which case architecture would probably be similar to Earth architecture, but able to build higher assuming the same materials.
But if we were trying to colonize a low-gravity world, we’d have to use an orbital station with centripetal-force “gravity” and only research stations on the surface, with a science crew rotation every 6-12 ish months to prevent bone loss.
This is actually the plan for the Moon and then Mars - use Gateway as a station to resupply and host crew rotations for Moon and Mars missions, and eventually to support long-term habitation. But until such a station exists, Lunar Gateway will be used for a waystation for crew rotations between the Moon and Earth.
Space engineering is about to become a very high demand field, on the absolute frontier of human exploration…
It depends on whether you need to contain atmosphere.
Kim Stanley Robinson’s Mars Trilogy goes into exquisite detail about the tradeoffs between different construction methods on Mars and other worlds in our solar system.
Habitat zorbs that bounce around the planet.
I love this image. Solarpunk future where THIS is society!
I read the closest we could likely get to this, in a sci-fi story years back. A habitat on Mercury. It sat on a rail that circumnavigated the planet. The heat of the sun caused the rails to expand, pushing the city forward. This kept it in the most habitable zone, as the planet turned (Mercury has a day longer than its year).
Not quite a zorb, but definitely a clear dome rolling around the planet.
Was that Saturn’s Children by Charles Stross?
That sounds about right. I read far too much sci-fi, and lose track of what is from what book. 😁
Care to recommend something ?
The only reasons skyscrapers exist is due to a lack of available footprint. If you’re settling a new planet just build out single story shit as far as the eye can see.
Lack of space might be a reason why they exist but it’s not the only reason they might be preferable.
How are we feeding people on this planet and what are people doing with their days? If we’re trucking in supplies and everyone is working at MegaCorp, you need skyscrapers. Spread out domes are needed if you’re relying on self-sufficient kitchen gardens and the main purpose of the inhabitants is simply to survive there.
And then call it “suburbs”!
A fascinating alternative is “a pressurized ETFE membrane… periodically anchored to the ground by steel cables.”
In plain language: Fiber-reinforced rip-stop ETFE (a thin, strong, light, transparent material used for yacht sails) is used to make a roof and walls with the area under it pressurized and anchored using very tall cables, hundreds of meters high or more, to create a sky. The covered area is huge, the size of a city, compartmentalized for redundancy. People are able to go about their daily lives without use of space suits and it doesn’t feel like you are “inside”.
Okay but what are we gonna do if some giant space cat decides to claw the barrier? I’ve always wondered what the inside of a air mattress is like.
Great link
It depends on the planet. Unless the planet was earthlike to some degree I would suppose MOST habitats would be underground.
Between this and the vegan fly trap, some good questions hah
You could do what they do in The Expanse. Spin the planet fast enough that you have artificial gravity, and build upside-down housing as you now fall away from the center.
Wouldn’t that also make the surface gravity negative and rip the planet apart?
Yeah, probably? I haven’t read the books, but I guess they have explanations of how they strengthen it.
I vote for blocks of bouncy castles several storeys high. No need for elevators.
I’m not sure about this, but I guess it depends on atmosphere. If The atmospheric pressure is weak, which is very likely for a low gravity planet, I’d guess domes would be better due to making a much more efficient pressure vessel than rectangles. If The planet does have a relatively high atmospheric pressure, traditionally shaped buildings are probably cheaper to make than domes.
I don’t think the skyscraper would be rectangular but likely more circular which would make them extremely strong. Our current technologies could easily build them and with compartments, they would be relatively safe. Building them would be quite difficult.
A comparable dome on the other hand would be subject to incredible forces if it was to be a single unit but hold that of a skyscraper. A dome of say 1000 foot diameter, would experience some 2 billion pounds of force at sea level atmosphere. It scales up bad and for anything large it is not practical nor do we have the technology or materials. Small domes on the other hand are quite practical and make a great deal of sense and we could build that.
In reality, a skyscraper would just be a tube with a pressure dome on top.
But they don’t really need to be that strong unless there’s expected impact.
Like lighthouses are circular to be strong because they need to take the ocean pounding.
Rectangles are nice because you can subdivide them into smaller rectangles and doing construction with a bunch of right angles lets you use lots of modular pieces (picture yourself at Lowes in the building materials section: everything’s a rectangle).
The larger the dome the exponential the forces become. A thousand foot dome has 2 billion pounds of force acting on it. We don’t have materials to handle those kinds of forces.
Still domes. One reason for domes is that it helps with holding pressure, which wouldn’t be a problem on an ideal planet. The other reason is that domes have low surface area, which means there’s less weight to bring to the planet from earth.
If domes are built, I don’t see then being built like those we typically see on Earth. Instead, I expect there to be layers of pressure sealing to prevent the escape of air. If you are going to put in several layers anyway, why not make the dome structure habitable.
