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Assume I have a human colony on The Moon. A meteor fragment gets by the defense system and smashes into a portion of the dome, let's say the hole is 1 meter in diameter, it's big.

Safety measures come into play and the section is sealed off. So only the one section is experiencing decompression. But the hole is large, so air is escaping fast.

Two questions.

1) Would the rush of air further damage the hole, assuming reasonable precautions against this were made? Whether it's multiple layers or whatever.

2) The main question though - would this incident ever cause the habitat section to explode?

I am writing a novella where there is a ticking time element. Certainly part of this is that the air is going for the people there. It would be nice to have the extra dram of further structural damage/danger imminent from the hole - but I don't want to introduce that if that really wouldn't happen.

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    $\begingroup$ A deflating balloon can still be popped...but it's more difficult and much less exciting than a fully-inflated balloon. Technobabble to the rescue: The outrushing air snarfed the gribbles, so the plasma floobs will explode, quite spectacularly! $\endgroup$ – user535733 Jan 6 at 17:54
  • $\begingroup$ Depends on the design of the dome. If it were me, I'd back up the main rigid dome with auto-patching metamaterials. Hole forms, breaking 'skin' on material pods; material flows out & hardens, filling the hole. $\endgroup$ – Carl Witthoft Jan 6 at 18:39
  • $\begingroup$ Also depends on the design of the plasma floobs. $\endgroup$ – pants Jan 6 at 19:17
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    $\begingroup$ @CarlWitthoft In the original Gundam Series they used a system, which crated huge, sticky "chewing-gum" bubbles to fix leaks. They would be deployed and, due to their mass to surface area ratio, be blown into the breach quickly. $\endgroup$ – TheDyingOfLight Jan 6 at 23:19
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    $\begingroup$ @TheDyingOfLight Which is a very good way to do it--leak-pluggers that can be tossed in the direction of the leak quickly. For a big enough habitat they might even be rocket-boosted. $\endgroup$ – Loren Pechtel Jan 7 at 0:44
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A 1 meter hole in a dome's superstructure is likely to severely damage something else below it. If you need an "its gonna blow in 5 minutes!" story element, have the impact cause fires that are threatening the Fuel or Oxygen storage.

Use the loss of pressurization and escaping atmosphere as something that hinders the efforts to repair the damage.

Here are some quick estimates so you can get an idea what this looks like:

Assuming a 20 meter radius dome (approx 132 feet wide) with a 1 meter hole and a shell that's 0.5 meters thick and is pressurized at 1 atm. According to this site's tool - https://www.copely.com/tools/flow-rate-calculator/ - The flow rate will be about 10,000,000 liters per minute.

The volume of your hemisphere will be around 16 million liters. Assuming the pressure stays the same in the dome, its will vent all 16 million liters in around 2 minutes - updated figures.

Realistically you will lose pressure as the air vents from the dome, so it will take longer. At half pressure the flow rate is still about 500,000 liters per minute though, so it doesn't slow down that much.

You can keep the pressure in the dome "stable" by having an oxygen leak fueling a raging fire, creating smoke and CO2 that replaces the previously breathable air.

If you don't do something like that and allow the pressure to decrease and air to vent, your dome will have LESS of a chance of exploding since fire needs oxygen to burn.

Another consideration is that the dome might rely on the air pressure inside to keep it up supported. Removing the air might cause the ceiling to collapse, but not explode outwards, it will implode inwards.

In regards to point 1) yeah the flowing air can cause more damage, but likely only to the immediate area surrounding the impact. You could have a meteor punch only a small hole at first, but the damage to the surrounding material causes it to grow as air rushes out, settling at your 1m diameter.

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  • $\begingroup$ A structure that requires atmosphere to stay erect is a chicken and egg problem. How was it constructed without the atmosphere inside and how did the atmosphere stay inside if it wasn't constructed? If it was built on scaffolding, why not just keep it in place? If the structure is just a giant balloon, wouldn't a strategically placed 2x4 keep it up? Why wasn't one put in place after inflation? $\endgroup$ – Muuski Jan 6 at 20:41
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    $\begingroup$ @Muuski: Inflate a mylar balloon, then put a hardier structure (one that can resist lunar regolith for more than a few weeks) on top of it. $\endgroup$ – Ghedipunk Jan 6 at 21:16
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    $\begingroup$ Like @Ghedipunk said, you could have an inflatable structure, put up a bunch of supports inside, pressurize it, and then cover it with a concrete made from regolith. Now you have a strong free standing dome that can support itself without internal supports, and it blocks radiation. It might not need the atmospheric pressure to stay up, but the damage from a large enough impact might weaken it to the point of eventual collapse in its absence. $\endgroup$ – abestrange Jan 6 at 23:01
  • $\begingroup$ The referenced calculator is for the liquid flow. For gasses, we must use a different one like this: Air Flow Rate through an Orifice $\endgroup$ – Alexander Jan 6 at 23:06
  • $\begingroup$ @Alexander Good catch, using the figures from that, a 1m diameter hole, 72°F, 1 atm inside, 0.01 atm outside, and discharge coefficient of 1 has a 10,000,000 liter/min discharge rate. That gives you a bit more than a minute and a half to get to safety. $\endgroup$ – abestrange Jan 6 at 23:35
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The structure wouldn't explode, but it may fall on the colonists.

Under normal operation, the colony hab dome expects 1 atm of air pressure inside, and nearly no pressure outside. This is a dramatic difference in air pressure, and the dome is a large, complex structure made from the lightest high-tension materials possible: A vast network of cabling that holds in place the air-tight panels, and keeps the panels under enough pressure so that they don't fly apart from the pressure on the inside.

The dome structure needs to be lightweight, because its material was shipped from Earth... The moon doesn't (yet, and may never) have the industry to create these cables and panels from resources found on the surface or available to be mined. Every ounce of material launched to the moon costs far more in fuel costs than it costs in manufacturing costs.

Even though the dome is lightweight by structural standards, if it lands on a human, that human will still be squished, even in the 1/6th gravity of the moon.

Such a structure would still fail catastrophically, though it wouldn't explode per-se. As the structure starts to buckle, it will make a horrendous amount of sound... and fortunately for the drama, it would start buckling long before too much air has escaped to make audible noise, so the colonists will hear their doom coming.

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  • $\begingroup$ This brings to mind an interesting design I've seen for a cover for a lunar city in a crater--cover it with a membrane, water and another space-hardy membrane. You don't need great strength even to span miles as the primary support comes from the air pressure vs a matching weight of water. Woe if something big enough to puncture the inner membrane hits, though! $\endgroup$ – Loren Pechtel Jan 7 at 0:43
  • $\begingroup$ Some parts could also fly off into space with the air rushing out (depending on how light the parts are and how fast the air is rushing out) so it could technically explode as a non-combustion explosion. $\endgroup$ – John Hamilton Jan 7 at 7:09
  • $\begingroup$ @JohnHamilton, indeed, I'd imagine it to be, if you have a bed sheet with a large bubble of air under it, then jump on that bubble, the air will rush out the sides. I'd be more worried about the structure falling on me, than that outrush of air, though. $\endgroup$ – Ghedipunk Jan 7 at 16:17
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No. But you can construct a scenario where it might.

Good design practice would likely be to build a series of double-walled bubbles, airlocked together, and maybe have some sort of active sealer that “clots” when exposed to air. A really cool looking alternative would be to have a big atrium/mezzanine with a giant glasslike wall. If artificial sapphire (or whatever other unobtanium) can be grown into arbitrary shapes, it can be an expensive, safer alternative to the material elsewhere (the bubbles get punctured by meteorites as small as 1kg, which is rare but causes constant maintenance while the dome is unaffected by anything up to 100kg, which doesn’t come up, etc with the handwaving).

Then the one-in-a-million meteorite punches through the dome. Someone slaps a patch on it, so it’s leaking slowly. But, oh no! Now that the dome structure has been compromised, cracks are slowly propagating. The bubbles are all sealed off from the mezzanine, and opening the air locks will send a pressure wave in, which could punch the glass out.

If you really want an explosion, you need to compensate for having a leakier pressure vessel by turning the oxygen mix much purer. Near-pure O2 gives you all the excuse you need for a real explosion.

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