So, you went to space and left the door open?
As discussed in my last post, this table is a “missing sidebar” describing what happens to things on spaceships after they are exposed to a hard vacuum. This was fun to research and I definitely found some surprising things.
Note that even though this is for a futuristic campaign (the Deeps of Lyrae setting) obviously I was not able to research the effects of vacuum on futuristic technology (e.g., that found in GURPS Ultra Tech). But I think you can extrapolate from here. Some discussion of the plausibility of all this is in my last post.
This table was written for the Deeps of Lyrae setting. That’s TL 11^ and has artificial gravity and routine space travel (as it is a Traveller variant). That is important to understand some of the items below.
Foreshadowing: I saved the most interesting thing for last. It is very cool.
Hard Vacuum Effects
- If the vacuum can get to them, liquids instantly evaporate. e.g., in a glass of water effectively the water disappears.
- Thin plastic bottles containing soda, water, or cleaning supplies may explode, tear open, or remain intact. It is likely that thin plastic containers will deform in shape (getting larger).
- If the decompression was explosive, I’d expect refrigerators and freezers are thrown open, spewing their contents across the room.
- Thin plastic bags of food in Paper/Cardboard boxes, such as crackers and cereals: Explode.
- Food containing moisture is turned into a crumbly dust.
- You might think vacuum-packed items would be safe, but not. Since vacuum–packing does not actually remove all of the air from a package (just most of it), a vacuum-packed foil package of ground coffee will inflate, deform, and explode – spraying ground coffee around the room.
- Tupperware can pop open or slightly deform, or it may be unharmed.
- Surprisingly (to me): If they are not thrown out of a refrigerator (or off of a high shelf) and onto the floor because of the escaping air of decompression, eggs will survive hard vacuum with no trouble.
- Fresh food, especially fruits and vegetables, explodes and turn to dust. No more strawberries on the Serenity. 😦
- Things like plastic toothpaste tubes and shampoo bottles may survive unharmed. If the cap was left open (or cracked), their contents will not.
- Glass Containers:
- Some glass containers may be totally unaffected: Vacuum tubes used in early electronics and early light bulbs were glass chambers built to survive vacuum. Or picture a sturdy thick-walled jelly container with a clamp lid or a heavy glass canning jar… you will still have jam. But if there are flaws in the glass even a thick container may shatter.
- As an aside, this means I think the GURPS rule I mentioned in my last post–one of the few pieces of guidance about equipment and vacuum that we receive–is actually wrong. It states that a wine bottle would be destroyed but as long as the cork was solidly in there and the bottle was thick I think it would actually be fine.
- Metal Containers:
- A metal can of food (or soda or beer, for that matter) will likely be unaffected by vacuum. (In the longer term, the dehydration of glue may cause the label to fall off.)
- Living Creatures (other than humans):
- I realize living creatures are not usually “equipment,” but this seems to go here. Maybe we are talking about trained bomb-sniffing service dogs.
- GURPS rules handles damage to human bodies, but what about other bodies? Almost all insects and animals will not survive vacuum (and die in a dreadful way), as per the GURPS rules for people.
- On the plus side, you might think hard vacuum will at least de-louse your ship, but there are a few exceptions. Most creatures have their bodily fluids sucked out, and their body then crumples inwards. But ticks, dragonfly nymphs, and dormant tardigrades can survive hard vacuum without problems. Whoa.
- Hydroponics or Farming Operations:
- …are destroyed. See The Martian.
- I think this has to be bad as I imagine there is some moisture in the fibers of clothing, but I can’t find any sources that have addressed what happens to the contents of your dresser if your stateroom gets a hard vacuum. The Goddard Space Flight Center said in 1969 that “degradation occurs in an unpredictable manner” and that organic materials are the least likely to survive unharmed. So: people who dress in fashions from the 1970s would be better off? (More polyester?)
- If they work in the way present-day computers do, they will stop working in a few seconds when convection and conduction stop as they can no longer shed heat. The motherboard will detect that the temperature is too hot to safely operate and the computer will shut down. However, when air is returned they can be started again and could be undamaged. (But see wiring, below.)
- The insulation on wires. Couldn’t find much on this. It will outgas but…? Does this matter? An open question.
- There is no way to remove heat from electrical wiring due to the loss of convection. This could be a serious problem.
- …will fail as they will either lose their lubricating properties, or they will outgas unwanted materials into machinery, or both.
- …will fail as they immediately dry up. Imagine all of the door numbers and signs falling off the wall. Well, if you still have gravity.
- Books and papers:
- If books and papers made from trees are still used in the future, that’s a problem in vacuum. Even “dry” paper is up to 10% water. However I’m not sure what will happen to them. I know it will be bad.
- Mechanical Watches:
- Another surprising find for me. It’s likely no problem. It was common for Apollo astronauts to wear an Omega watch on the outside of their spacesuit, during the moon walks, so that they could use the stopwatch feature to time activities
- Suction Cups:
- …fall off.
- Plastics (and the atmosphere):
- Significant offgassing from plastics can produce toxic compounds that are still present when air is restored, but air processing systems are likely to handle this problem anyway, as normal offgassing is already a problem in recycled air systems and filters will be in place.
- There still might be a problem with unusual ship cargos, however? What if you had an entire cargo hold full of plastic? Sounds bad.
- Small Electronic Devices (powered or unpowered)
- may work fine. e.g., A cellular phone will work in a hard vacuum.
- Electric Motors (if powered):
- Motors will short out or may operate for a short time, then break.
- They may operate briefly, then overheat because of the lack of cooling air and convection, causing a component to fail at a high temperature.
- They may short out because air insulates them against arcing and when the air is removed new electrical connections can be made.
- Their components may deform or release volatile gasses that interfere with the operation of equipment.
- (See also the last entry on this table for an additional hazard.)
- Electrical Equipment: (if powered)
- Old-fashioned fuses will blow at half their rated capacity because they cannot shed heat, but modern circuit breakers depend less on air circulation and are not subject to this problem.
- Some solders are not suitable for vacuum and so soldered connections will be broken.
- All circuits will operate at higher temperatures and unprotected circuits will overheat, but cannot catch fire because of the vacuum.
- Plastic components in electrical equipment such as casings and insulation may melt, producing a new configuration of wiring and potentially electrical arcs as noted above.
- In general, if vacuum is present but power is not switched off, the equipment could stop working because of one of the above three problems. Components damaged by vacuum will need to be replaced – the system will not just start working again when air is restored and power is switched back on.
- Water will boil out of the toilets, potentially spectacularly if combined with the moving air of an uncontrolled decompression. That should be fun.
- Aside from that, pipes should hold up well. The cement used to seal connections between plastic (e.g., PVC) pipes may eventually degrade, but if the pipes are mechanically sealed, even pressed tightly into each other, this will not be much of a problem and it may take a long time to manifest. If a ship is left in a hard vacuum for years and air is restored, the plumbing may have a few new leaks.
- You could specify that the reactor keeps working as it is engineered to withstand vacuum, or you could stay that it switches to “emergency standby” that keeps the core/plasma/antimatter/whatever safe, but doesn’t do much else. If the reactor stays online and continues to power the whole ship you might run into other problems as specified above!
- Reactors are dangerous enough anyway that if used shipboard I expect they would be built with safety systems that shut down the reactor when atmospheric pressure is lost.
- Is it possible to keep running them? Not sure. The reactor core would already be sealed. But even though the core will be sealed, if the reactor isn’t shut down the supporting equipment is electrical and will overheat. In general it is subject to the problems described above.
- Bloodthirsty GMs might be interested in what happens with a system like a fusion reactor where parts need to keep running — you need an electromagnetic field to contain the plasma. Or a fission reactor that needs cooling machinery to keep running to prevent a meltdown. I imagine that whatever shutdown is engineered to accommodate the problem of decompression would handle it, otherwise a loss of atmosphere in the reactor would immediately destroy a starship and kill everyone in a gigantic explosion. (But who knows. Weirder ships have been built — see “The Case of the Sulfuric Acid Submarines” in my last post.)
- A flooded fission reactor in a nuclear submarine will be ruined forever, but a fission/fusion/anti-matter/other reactor that was safely shut down when it was subjected to vacuum will probably work again if atmosphere is restored, as it was designed to shut down.
- Metals That Touch Other Metals
- ➡ This is the coolest thing in this table, just so you know.
- Over time, in a vacuum some metals in contact with each other may adhere together if they are clean enough. This can happen if metals rub together after lubricants or contaminants evaporate away, in a process called “cold welding” or “vacuum welding.”
- Given time, metal latches, locks and fasteners may cold weld. If metal is subjected to a continuous vibration (as from a starship engine?) that increases rubbing, cold welding is more likely.
- Cold welds are strong and permanent.
- Cold welding can be fairly easily prevented (for example, by painting), so doors in a spaceship will not fuse shut… but mechanical locks might. Similarly, internal components of motors and equipment that are not designed for vacuum may not be so lucky. If the vacuum lasts a long time, many machines with metal internal components that were subjected to vibration might be ruined because parts of their insides are welded together.
- However, since this is so easily prevented (e.g., by painting) it may be that anything designed for shipboard use is already safe from a cold weld issue. Yet things brought on board that were not designed for vacuum use would still be affected.
- Important: Underline this. Put a star next to this. This problem affects machines that are turned off. It has nothing to do with electricity.
All in all, decompression sounds expensive unless you are a dragonfly nymph who wears polyester with an Omega wristwatch. And likes eating jam and eggs. In the dark.
What did I miss? What did I get wrong?
(Image credit: This is a still from the 1979 movie Moonraker. Like it? Check out “Thrown Out the Airlock” on TVtropes.com.)