First, yes I was inspired by this question: "How do you check if a room behind a door aboard a spaceship has an atmosphere/pressure?"

I wanted to take the scenario further, instead of asking how the ship could be designed to handle this I want to know how a survivor could work their way through this.

Say you are on board a large space craft and it was damaged by a meteor. All the power is out and all bulkheads are closed and you need to get to the bridge.

The ship wasn't engineered to provide any kind of instrumentation to solve this problem under these circumstances (the computer does the checking).

How can one survivor using what he has around him check if the door has pressure or not behind it.

  • he can't use a battery to power the sensors
  • no magic tricorder hand sensor to do it for him
  • you are welcome to imagine any materials that could reasonably be present in this situation. The scale and purpose of this ship will remain unspecified (though more general solutions would be appreciated)

Edit People seem to need a scenario:

To reduce construction costs we, FUBAR corp, fitted our newest commercial transport ship with the latest economical emergency pressure seal doors. They feature top of the line integrated pressure sensors that constantly monitor and report to the ship's computer. We removed costly antiquated redundant mechanisms with our new distributed multifunctional failsafe autonomous safety system built into every door. Each doors micro computer can handle safety and security locking procedures independent of ships central computer. In the case of power outages our new doors each utilize the latest tritium backup battery capable of performing for weeks without recharging. Our doors can even serve as a passive comm system in emergency situations.

And there's more, our improved luxury restrooms .......

Surprise the backup batteries were all defective because they cut costs and went with the cheapest distributor or no one realized they fail when exposed to certain frequencies of radiation.

  • $\begingroup$ When you say "the computer does the checking" and that the ship doesn't provide instruments I'm assuming you just mean they aren't readily available since the computer also needs these instruments if it is to check anything. $\endgroup$ – Ludo Oct 25 '17 at 22:50
  • 1
    $\begingroup$ @anon - airplane doors are not designed to be open at altitude. And it's physically very difficult, if not impossible to do so. But, if you want to build a design flaw into your scenario, you certainly has the right to do it. $\endgroup$ – Alexander Oct 25 '17 at 23:05
  • 1
    $\begingroup$ Its not a built in flaw, its the absence of forward thinking, kind of like the bulkheads on the titanic. $\endgroup$ – anon Oct 25 '17 at 23:09
  • 1
    $\begingroup$ @anon - this looks to me like a bigger design flow than Titanic's. At least those bulkheads should have worked in many other disaster scenarios. $\endgroup$ – Alexander Oct 25 '17 at 23:22
  • 1
    $\begingroup$ @anon - the doors will have pressure locks. Upon unlocking it, the air either start slowly seeping, if the door is designed for opening, or user just won't be physically able to open the door if it is not designed for opening and there is high pressure gradient. It's never going to be "Unlock, and it'll fly open". $\endgroup$ – Alexander Oct 26 '17 at 0:56

No material is perfectly rigid. For example, a vacuum will cause the door to slightly bulge toward the vacuum. The cheaper the door, the more it will bulge. Therefore:

  • Micrometer Starting with a door that has correct pressure on both sides, measure two lines. One from the hinge toward the center and the other from the latch toward the center. Lines should end at the furthest points the micrometer can measure. Do the same thing on the test door. The micrometer will measure a shorter distance on a door blocking a vacuum.

  • A staight-edge For cheap doors a yard stick will do. Assuming (and it might be a whomping big assumption) that the doors are flat, a yardstick can be placed against a cheap door and space will exist between the yardstick and the door blocking a vacuum.

  • Fluid test All materials under stress vibrate. Assuming (yup, another whomping assumption) that the ship isn't shaking something awful, a cup of water could be held against the door and the water observed. Ripples=vacuum.

  • Temperature A door blocking a vacuum will not have a heated atmosphere behind it. It will be colder than doors blocking atmosphere (could be spoofed if the heaters are down).

  • Brute Strength Assuming (yeah, yeah, yeah) the door opens into the room with atmosphere, simply try to open it. You'd be surprised how much force a full atmosphere holds against an object. The door will be very hard to open. If you do happen to crack it, the force of rushing air will likely pull it out of your hands and reseal it.

  • 1
    $\begingroup$ For your fluid test, how would you know if the stress comes from having pressure or not having pressure? Either could put stress on the system, and that's not even including the fact that the walls are interconnected even if the rooms are separate. Would you not see ripples if the room below you was vacuum but not the room in front of you? $\endgroup$ – Flater Oct 26 '17 at 12:45
  • $\begingroup$ You can make assumptions about the door, as long as they don't explicitly involve mechanics for pressure testing. You made some good points though I think brute strength is wrong as it would be easier to open in to a vacuum than harder. $\endgroup$ – anon Oct 26 '17 at 13:22
  • $\begingroup$ @anon, my brute strength test has the door opening into the room with atmosphere. You couldn't stop the door from opening into the vacuum. $\endgroup$ – JBH Oct 26 '17 at 14:56
  • $\begingroup$ @Flater, that's a good point, but the structure around a door (any door, really, even in your house), is usually quite a bit better built than, for example, a wall. Consequently, you're correct that if you tested the wall it would probably vibrate even more than a door would, but the framing around the door would isolate the door from the wall... and the requested test was for the door, after all. $\endgroup$ – JBH Oct 26 '17 at 14:57
  • $\begingroup$ @JBH: The average house door is not airtight. Logically, a spaceship door is airtight (otherwise the question itself is moot, air would be leaking everywhere), which means that the door fully touches the wall in order to create a hard seal. Hard seal = physically fully connected by a rigid body. Unless you're using an airtight membrane instead of a rigid wall;, but then the question becomes moot again because the membrane would change shape (flex) based on differences in pressure on either side of the wall (thus making it unnecessary to test any further). $\endgroup$ – Flater Oct 26 '17 at 15:01

"Built in pressure checkers: ears."

If you have been scuba diving, or been around tanks of pressurized gas, you will note that the ring they make when tapped (or dropped) changes depending on how much pressure remains inside.

https://www.youtube.com/watch?v=WbOXM8cPFEM scuba tanks

In this video he demonstrates the principle. Higher pressure = higher pitched ring. Lower pressure = lower pitched ring. I had a scheme to hang tanks in a row according to pressure and play them with mallets.

You could do that on your ship. You could also use the principle to test your doors. Ideally, find a door which you know connects pressurized rooms and which is similar to the door you are unsure about. Tap the known door to determine the pitch it makes. If you can find several that would be ideal - hopefully this cut rate ship you are in is made from standardized parts to make repair easy.

Now the door in question. If the sound it makes when tapped (or struck) is the same as that made by doors with pressure on each side, it likely has pressure on each side also. If it makes a lower sound then it has less pressure on the far side.

  • $\begingroup$ I actually thought of this too though I was unsatisfied with the fact that what if the person never bothered to learn what sound a pressurized bulkhead makes then this wouldn't help him here. If you think about it how many people go around knocking on things just to remember what they sound like. But it is an ok answer. $\endgroup$ – anon Oct 25 '17 at 23:07
  • $\begingroup$ The idea is that he might learn right then. If he knows low pressure makes a lower tone than high pressure and he has one (or more) similar doors (or bulkheads) with known pressure characteristics, he could deduce the mystery door once he determines the tone qualities of the known doors / bulkheads. $\endgroup$ – Willk Oct 25 '17 at 23:43
  • $\begingroup$ I get that, though that requires there to be more than one door and that at least one of the doors sounds different. its certainly plausible But im still hoping for a fun macguyvered solution $\endgroup$ – anon Oct 25 '17 at 23:46
  • $\begingroup$ Scuba tanks have a (mostly) standardized size. Spaceship corridors likely exist in many variations as to thickness of the wall, the material used, and the width/height/shape of the corridor. All of these influence the sound that you would get from knocking. This system would only work if the person has experience with the knocking sound of a similar wall+door+corridor. $\endgroup$ – Flater Oct 26 '17 at 15:05
  • $\begingroup$ @Flater which was my objection to this. However its not unrealistic. In the very least all the internal emergency pressure doors would likely be standardized on a ship model. Simply because a pressure door is costly enough to make no sense in not making that cost effective through standardization. It is possible that there could be some odd doors like for service hatches but in general all the internal doors on a ship would likely be the same. $\endgroup$ – anon Oct 26 '17 at 17:26

Other authors have tackled this exact same topic, and the answer is that a manual instrument panel is usually built into the frame/door such that these sort of checks can be performed, and the door cranked open manually.

The outer hatch undogged and Dana entered what was clearly an airlock. She cycled the door then checked the telltales.
"Uh . . ." she said. "The other side of this is vacuum?"
There was a banging on the bulkhead and the light cycled to green.
"Try it now."

The hatch opened outward. If it was really vacuum, she was about to do a Dutchman without a spacesuit. She thought about that for a second. This was just another test. She was good at tests.

Beneath the main airlock control panel is the manual testing system. Manual tests of atmosphere integrity may be obtained . . .

Thank God she hadn't slept through that class. She opened up the access panel and twisted the knob. Air immediately started sucking out. She quickly closed the test knob. Asking another question was out. There was no way they were just going to kill an arriving noob. Somebody was playing silly buggers.
She put her ear to the steel bulkhead. Faintly, she could hear something that sounded very much like a small motor.

"Tell you what," she said. "I'll open the hatch if the joker with the vacuum cleaner will shut it off."

The hatch cycled from the other side and a tall Coxswain's Mate First Class grinned at her.

"Welcome, junior space eagle," the CM1 said. "Come in! Come in!"

- Citadel, by John Ringo

Otherwise there is no way for you to check except to open the door and take a deep breath.

Automation really can reach a point where it does more harm than good, such as having an AI perform all these functions, thus having a single point of failure for a lot of very critical ship-board functions.

It would be deadly design flaw for a space ship.

  • 1
    $\begingroup$ "The ship wasn't engineered to provide any kind of instrumentation to solve this problem under these circumstances (the computer does the checking). " - this includes the test valve which was the answer to the related question $\endgroup$ – anon Oct 25 '17 at 23:13
  • $\begingroup$ @anon - I didn't read the other question. What I am saying, however, is that such systems would be built into any door, even if the ship had been intended to be automated. $\endgroup$ – AndreiROM Oct 25 '17 at 23:14
  • $\begingroup$ the pressure valve is instrumentation explicitly engineered to check the pressure in the absence of electric censors and perhaps this is an alien ship and they don't believe in the same level of redundancies as us. $\endgroup$ – anon Oct 25 '17 at 23:20
  • $\begingroup$ @anon - yea, but I went and got the quote and everything, so I think I'll just leave it up :-P $\endgroup$ – AndreiROM Oct 25 '17 at 23:42
  • $\begingroup$ I appreciate the effort, Im just trying to focus on how a person could solve this. $\endgroup$ – anon Oct 26 '17 at 13:29

The survivor should be able to just use his eyes after a short period of time as any doors with a vacuum behind them would have condensed frost on them from the water vapour in the air freezing when it made contact to the doors.

Even if the heating in the ship was damaged the temperature variance between the vacuum of space and that which would allow the survivor to still be able to physically move around etc. is significant enough for water vapour to freeze on contact.

  • $\begingroup$ Welcome to WorldBuilding! Interesting answer. If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Secespitus Nov 3 '17 at 10:39

Doors can be hinged or sliding. A sliding door would work much like a gate valve -- somewhat wedge shaped to make a jam seal. Put normal pressure on one side of it, and you have tons of pressure jamming the door against it's seal.

A hinged door is similar. If it opens toward you, it has your room pressure pushing it closed. If it opens away from you, then that pressure is on the dogs that pin the door closed.

So, to answer the question: You try to open the door. If you can open it, the pressures are equal on both sides. If you can't then you are stuck.

  • $\begingroup$ Though I didn't explicitly rule out engineering the door to not open when exposed to a vaccum, it sort of defeats the expressed spirit of the question. $\endgroup$ – anon Oct 26 '17 at 13:27
  • $\begingroup$ I think it would difficult to engineer a door to open under a significant pressure differential. This would be the default. Designing a big door to be pressure tight in both directions is tough. The simplest such door used on board ships has a central wheel that turn it a quarter turn shoves 6-8 tapered bars over the door jam pulling the door tight against it's seal. Yeah, if you had these greased, or used teflon siders you might still be able to open it with full pressure against it, but it would be an easy design to make it is so that the seal compression interfered with dog movement. $\endgroup$ – Sherwood Botsford Oct 27 '17 at 14:25
  • $\begingroup$ You don't think they could make slidey pocket doors capable of supporting a pressure seal? $\endgroup$ – anon Oct 27 '17 at 14:32
  • $\begingroup$ I don't think it would slide when pressurized, without a whole lot of detailed design work. That is it would take deliberate effort to design one that could be opened. An example of this would be the penstock valves at a dam. $\endgroup$ – Sherwood Botsford Oct 27 '17 at 20:53
  • $\begingroup$ The scenario could be written to avoid this option. If the protagonist has to basically destroy the doors to get through them he has to be absolutely certain before trying to 'open' the door. e.g. maybe he can remove the entire door unit from the ship's frame $\endgroup$ – JeffUK May 9 '18 at 22:55

It is highly unlikely that there would be a door that can be opened into a vacuum.

Any spaceship door can generally be categorized as:

  1. Door that opens into space;
  2. Door that faces space, but should never ever be opened when in space;
  3. Door that opens into the inside of spaceship, but can serve as airtight barrier in case of emergency.

If you think of any of these types of doors and their purpose, it is only logical that every type of door would be equipped either with a slow-release valve or a pressure indicator, or maybe even a locking mechanism that won't allow to open doors into vacuum.

  • $\begingroup$ People seem to need a scenario: 'to save on construction costs We fitted our commercial transport ship with the latest economical emergency pressure seal doors. They feature top of the line integrated pressure sensors that constantly monitor and report to the ship computer. To save costs of unnecessary components we added a backup battery built into the door to keep the sensor powered in case of outages." Surprise the batteries were defective because they went with the cheapest distributor. $\endgroup$ – anon Oct 25 '17 at 23:44
  • $\begingroup$ All right, all right, I can live with faulty pressure indicators, as long as they were not intended to be faulty :) $\endgroup$ – Alexander Oct 25 '17 at 23:56

You're in a spaceship (presumably IN space at the time) and the craft gets struck by a meteor resulting in a complete loss of power throughout the ship.

Presumably this means that any form of artificial gravity has stopped working so you're now floating about.

And the life-support systems have just switched off.

I'd say this might necessitate the need to find a suit and get in it - hampered by the lack of gravity. Once in the suit, it kinda becomes academic if you open a door to the vacuum of space - other than the fact that there would be a sudden depressurisation. Knowing this fact, the survivor could anchor themselves to something first before opening the door/hatch.

Although a further thought occurs. If the craft had been designed by people that have placed all the responsibility for such safety measures in the hands of the ship's computer without the forward thinking of placing visual gauges and such, have the designers even put manual release mechanisms on the doors? Given that there's no power and doors/hatches presumably lock in the event of a power failure your survivor might need a way to burn through the doors???

But if there IS a way to manually open a hatch or door and there is no visual way to tell if the compartment beyond is pressurised or not and your survivor is on a ship that clearly puts crew and passenger safety as an afterthought (there might not be any emergency suits or, to put it in there with your Titanic analogy, there might not be ENOUGH suits) AND if the survivor has no choice but to open the door... I'd say they better cross their fingers, say a prayer and hope for the best.

Or sit tight and wait for damage control parties to do their job.

FUBAR Corporation... a subsidiary of ACME Enterprises...


Put your ear to the door and tap. If you hear anything there is an atmosphere on the other side of the door.


Let's use 'things we know are on the International Space Station' to determine whether or not something is likely to be on-board.

First, take a leak-repair kit from the emergency station. If sections can be sealed off, then even the cheapest of ship builders would put a leak repair kit in each section. (see the ISS Leak Detection manual https://caneus.org/fbw/downloads/2007/GravesBriefing.pdf)

Secondly, take out your Space Ship Toolbox and grab your drill.. uh oh, this is where we hit a snag. It seems that we don't have a great selection of things-for-making-holes-in-things. Not surprising in an environment where 'holes-in-things' can kill you.

Plan B, the medical kit, no help there either unless you want to cut a hole in the door with a scalpel (no dental drill for instance)

Plan C, Look again at the tools, there must be one you missed. Aha! "Draw 5 - Screw Extractor Kit" hidden in there will almost certainly be a set of drill bits.

Now, you just need to set to the nearest door* with the smallest drill bit you have and drill a hole somewhere where it will be easy to patch. The state of the atmosphere (or lack thereof) in the adjoining compartment will become immediately apparent. If it starts sucking, stick a patch on it and move on. If not, you have a winner!

Just make sure you shove something through the hole and that it actually comes out the other side; the door is likely to be double-skinned at least.

(*or use @JBH's post to guide you to a good candidate)


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.