Just to add to the other answers, the only place you could build something like this outside of Earth, with no radiation problems and simple construction, is in the upper atmosphere of Venus at the cloud tops. Because the Venus atmosphere above you would be comparable in thickness to Earth's. Will We Build Colonies That Float Over Venus Like Buckminster Fuller's "Cloud Nine"?
The Earth's atmosphere is 1.225 kg/m3. So to have the ten tons of Earth atmosphere above you for radiation shielding, in a domed enclosure, if you just do it with air, you need about 8 km of atmosphere above you. There I'm just assuming uniform density in a pressurized dome - of course it would be somewhat less dense at the top. But reasonable first estimate.
It would be quite a challenge probably to build a dome that has ten tons of material per square meter, though in principle it should work, held up by the pressure of the air beneath it. For the Stanford Torus and other such designs they talk about 4.5 tons per square meter shielding, as adequate but that also would be a major engineering challenge I'd have thought, for a transparent city dome.
If you do it just using atmosphere, that reduces it to less than 3.7 km of atmosphere, to have enough shielding to be equivalent to the recommendation for a Stanford Torus.
For a garden though, farms and such like, largely tended by machines perhaps, hydroponics and so on, you wouldn't need it to be shielded in that way.
Also for short term visitors. But for long term residents, especially living there from childhood it seems a significant issue. Who wants to significantly increase their chance of getting a cancer that would cut your life short by a decade or more?
The Caldera of Olympus Mons is deep enough to provide significant shielding from cosmic radiation if it was covered over and the residents lived at the bottom of it. Especially since the dome would arch above it.
I'm interested in it for planetary protection reasons - since the air is so thin at the top of Olympus Mons and it gets much less dust - is it a place where humans could land on Mars without risking irreversibly introducing Earth life to the planet?
I don't see how that is possible with present day technology - especially since a crashed spacecraft could easily miss its destination - and also very hard to land there with present day technology - but might it be in the future? Maybe also with new understanding of conditions on Mars? Could it somehow be contained and separated from the rest of Mars? Does it matter that it is still active on geological timescales?
Olympus Mons is 24 km above the surrounding surface. The caldera is up to 3.2 km deep so deep enough to be protected, indeed since the dome would surely rise well above the surface, well protected.
It's 90 km long by 60 km wide. Olympus Mons Caldera
Newton (lunar crater) on the Moon is even deeper, while still not that huge (not either hundreds, or thousands of kilometers in diameter), over 6 km deep, diameter of 79 km. And it's near(ish) to the lunar south pole with its ice. Perhaps this might be a location for some future domed city on the Moon? Newton Crater on Google Moon
And there are many other smaller craters on the Moon that would surely give substantial protection from atmosphere.
Of course - that's a lot of mass of atmosphere too. Same problem as for the O'Neil Cylinder - that nitrogen particularly is in rather short supply in the inner solar system.
So it seems a waste to use it just for radiation shielding. Probably better to go for the very thick plastic option, or even water if you can find a way to use that - water much more abundant than nitrogen. Maybe in the form of clear ice? Like an Ice hotel?
Icehotel (Jukkasjärvi) melting, photo Laplandish
File:Coming icehotel.jpg 'Coming out' Art suite in ICEHOTEL Jukkasjärvi, Sweden, 2008. Made by Maurizio Perron. photo by
Laplandish
Ice would not be stable on the Moon, it would evaporate quickly in the vacuum. But cover it on the outside with a thin layer of plastic, same on inside perhaps too, to help keep it cold, and it might be a useful building material for a transparent dome / greenhouse?
WHY DOMES?
They have to build spherical or locally spherical structures in space - at best - tubes with rounded ends, or toruses or some such. The reason is the ten tons per square meter outwards pressure from the air inside the habitat.
If you build on a surface, then it can be a section of a sphere, because you have solid rock to anchor it to around the edges of the habitat.
When you see an artist's impression of a rectangular greenhouse on Mars - as you do sometimes - my first question is - how does this avoid exploding outwards? Even a greenhouse at ten percent of Earth's pressure, enough so that a human can survive for a while with just an oxygen mask rather than a full pressure suit inside - will have one ton per square meter outwards pressure. You can only have rectangular habitats if there is a vacuum or near vacuum inside.
You could have rectangular habitats with spherical or tube shaped etc living quarters inside them.
METEORITE PROTECTION
On the other hand - you can protect against micrometeorites with whipple shields, whichcan be transparent - multi layers of thin material to cause micrometeorites to fragment before they hit the main part of the habitat - this is how the ISS is protected for instance. And not quite like a balloon - the fabric can be made rip-stop, a large meteorite then would make a big hole, but it wouldn't immediately tear part, and then you put a patch in place quickly if something does get through. And have shelters inside which the people can rush to in an emergency, which would be very rare indeed.
An ice dome with the ice meters thick would probably be quite well protected - you would heal any breach - first with a patch on the inside to stop the air rushing out - then you patch it on the outside too, and pour water into the gap and let it freeze.
You can use similar ideas for settlements in space, then you can maneuver the settlement itself to avoid a large meteorite and divert smaller ones.
LUNAR CAVES
But safest of all probably is to live in a cave, like the lunar caves. These may be large enough to include entire cities inside them.
Lava tubes safe enough for Moon base - BBC News
See also my new Case For Moon - Open Ended Positive Future For Humans Based On Planetary Protection - Executive Summary
and in much more detail:
About the Author
