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This question relates to an attack on a biological space vessel.

My vessel is a space station made from wood, with an oxygen-rich atmosphere inside it. It is under attack and the attackers have decided to "burn" through the wood and let the air inside escape.

What will happen when you heat the outer surface of the station to high temperatures in a vacuum?

also:

What method would the attackers use to heat the wood?

The attackers have very advanced but scientifically plausible technology.

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    $\begingroup$ Wood to build a space station? $\endgroup$ – L.Dutch Aug 1 '17 at 10:13
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    $\begingroup$ @L.Dutch Amish in space? pool.theinfosphere.org/images/a/a8/Amish_spaceship.png $\endgroup$ – Hyfnae Aug 1 '17 at 10:25
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    $\begingroup$ @AricFowler heating is the new cool? ;) $\endgroup$ – Erik Aug 1 '17 at 10:55
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    $\begingroup$ + for wood space station. I hope it is swanky teak and ebony, with brass fittings. $\endgroup$ – Willk Aug 1 '17 at 11:32
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    $\begingroup$ @a4android : [citation needed] $\endgroup$ – Eric Towers Aug 1 '17 at 16:48

12 Answers 12

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Charcoal

If you heat wood in the absence of oxygen you get charcoal.

Charcoal is a lightweight, black residue, consisting of carbon and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis — the heating of wood or other substances in the absence of oxygen (see char and biochar).

This will also result in a reduction in volume meaning your space station will most likely no longer be airtight as a result of surface cracking. You may well start fires on the inside once the heat penetrates to the oxygen rich interior. This would cause rapid failure of the wood/charcoal layer and subsequent loss of pressure containment.

The easiest way to add heat would probably be to use lasers. Keep it simple.

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    $\begingroup$ Indeed - fire a powerful laser at it and you'll probably start a fire on the inside after a while $\endgroup$ – Matt Bowyer Aug 1 '17 at 11:15
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    $\begingroup$ Not really a reduction in volume. Rather, you remove the non-carbon material, leaving a porous structure. (Which is why charcoal is often used for filtration.) Then the interior atmosphere leaks through the porous and now hot structure, oxidizing the remaining carbon. $\endgroup$ – jamesqf Aug 1 '17 at 18:14
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    $\begingroup$ Or, you know, carry the oxygen with you. A chainsaw is probably an even better approach. $\endgroup$ – Mast Aug 2 '17 at 12:43
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    $\begingroup$ @Mast, I'd love to see the effect of someone trying to use a chainsaw while unsecured in microgravity, for science, and schadenfreude. Even a power drill would be amusing enough. $\endgroup$ – Separatrix Aug 2 '17 at 13:27
  • $\begingroup$ @Separatrix that mental image just made my day I have an image of a redneck in a space suit on an EVA from the spaceship "General Lee" and saying "Hey Cap'n, Watch This!". Thank you :) If I had artistic ability, I would draw a cartoon and send it to you, or post it here, or something. $\endgroup$ – Paul TIKI Aug 2 '17 at 14:49
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It'll char.

...the decomposition of wood by heating to a temperature of 450°–550°C in the absence of air. The products of this process are gases (carbon dioxide, carbon monoxide, methane), liquids, and a solid residue —charcoal. The gaseous and liquid products separate out as a mixture of steam and gases, and when the mixture is cooled, a distillate is obtained. The distillate, in turn, separates into pyro-ligneous acid and wood tar. The acid can be treated to yield acetic acid, methanol, and other products. Fractional distillation of the wood tar yields inhibitors (the fraction rich in phenols), used to stabilize the oils and benzines obtained by the cracking process, and flotation oil, used in ore dressing. The charcoal is used in the production of activated charcoal, carbon disulfide, and other substances. On the average, destructive distillation yields approximately 32–38 percent charcoal, 45–50 percent liquid products, and 16.5–18 percent gaseous products.

In order to heat it to that temperature in a vacuum, you really have two options: a) some sort of beam at IR/microwave frequencies, e.g., a laser or simply a parabolic mirror near a star, or even simply a regular transmission antenna.

b) a flamethower: high pressure gas-air mix, ignited at a very short range. Since there is no ambient air pressure, the jet will disperse very quickly, so it will have to be at very short range.

Do bear in mind though that organics tend to have very short survival in a space environment. The wood of your ship will get brittle within hours and break up within a week even without someone attacking it, less if it's near a moderately respectable star--strangely enough in almost the exact way that your question asks.

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    $\begingroup$ There's another name for your "flamethrower." It's "rocket nozzle." $\endgroup$ – Solomon Slow Aug 1 '17 at 15:52
  • $\begingroup$ Or just a soldering iron with a large enough battery attached to the ship by a quick mission - the attackers might want to retreat until the process becomes explosive. Now that I think of it, a simple lens might do it if they are in a solar system ... $\endgroup$ – Hagen von Eitzen Aug 1 '17 at 19:51
  • $\begingroup$ @HagenvonEitzen: Mirror; a lens would end up having the shadow of the attacking ship behind it $\endgroup$ – nzaman Aug 1 '17 at 19:56
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Christmas Tree Rocket

Wood starts to burn at 450°F (233°C). In space, all the moisture in the wood will be sucked out by the vacuum of space. When facing the sun, the skin will heat up to 250°F (121°C) and on the shaded side, cool to -250°F (-157°C). Some cracking will definitely occur.

I could tell you scenarios where your space station would spontaneously combust, but what intrigues me is how would you pull off a wood space station? Would the wood be growing in space? Would the station somehow be alive? Because green wood would still ignite below the auto-ignition temperature of a metal like aluminum, but above the temperature where aluminum loses it's structural integrity, which is 1112°F (600°C).

Wood as you know is mostly carbon. An application of carbon such as carbon fiber under the most optimal conditions will burn at 572-932°F (300°-500°C) which is substantially higher temperature than the 450°F for wood.

Live wood means that your space station would have the ability to heal itself when a tiny meteor strike hits. This is something aluminum cannot do. It could disperse heat (sap could pull heat away from an area), even grow. That means that it might make it's skin thicker in some areas to protect from exposure to the sun, be able to heal from micro meteors or have symbiotic insects or fungus that could help enhance it's ability to thrive.

Wood as we think of it now has drawbacks. But wood has many features that could make your idea really intriguing.

Good luck.

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  • $\begingroup$ I removed the image. I wouldn't want science fiction based on faulty science! ;). $\endgroup$ – gwally Aug 1 '17 at 18:41
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    $\begingroup$ Gawd I love that picture of the tree-rocket. It's the Space Xmas project. Kris Kringle steps in for Elon Musk....(I think I need sleep) Oh yeah, interesting points about certain properties of wood that might be desirable in the deep dark. $\endgroup$ – Paul TIKI Aug 2 '17 at 14:53
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What happens when you heat wood in the abscence of oxygen is pyrolysis:

Wood, or biomass generally, consists mostly of polymers of sugar molecules. When it is heated rapidly in the absence of air you get some small gaseous molecules (CO, CO2, H2, CH4, and other light hydrocarbons), thousands of types oxygenated hydrocarbon molecules that are liquids at room temperature, and a solid char fraction we will call char that is similar to coal or charcoal but with a lower heating value due to increased oxygen content.

That is, in short: your biological polymers will break up and new, simpler molecules will be formed; the main thing is, of course, there will be no flames. According to this other answer, this holds equally well for a vacuum (no air at all, not only no oxygen); it's talking about paper, but paper and wood are basically the same in this context:

Paper is mainly made from cellulose, and when heated in a vacuum cellulose undergoes a process called pyrolysis. The mechanisms involved are enormously complicated.

As for the method, it could be any suitable type of radiation, I guess, like focused coherent light (a laser), or pyrotechnics such as thermite.

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    $\begingroup$ There could be flames - those small gaseous molecules might be incandescent for a second or two. $\endgroup$ – Willk Aug 1 '17 at 11:31
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There are two ways of burning through the hull of a wooden space station.

One, heat the external surface of the hull until the oxygen-rich atmosphere in its interior catches fire and burns through from the inside. Lasers or any powerful source of electromagnetic radiation, for example, infrared heaters can do the trick I note @MattBowyer came up with a similar concept in comments and which I only noticed after writing this. Another case of great minds thinking alike.

Two, use a cutting torch with a jet of super-heated oxygen. This will burn its way through wood. How's that for nice and simple?

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    $\begingroup$ Drive a bunch of Iron nails into the hull and then use induction to heat them up $\endgroup$ – Paul TIKI Aug 2 '17 at 14:55
  • $\begingroup$ @PaulTIKI Nice idea. That will work too. $\endgroup$ – a4android Aug 3 '17 at 2:25
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Wood becomes charcoal as explained in other answers.

It has rather low thermal conductivity, about 3 times higher than styrofoam, and much lower than wood. Also it blocks for example IR radiation quite well, so you will really have trouble heating anything except the surface.

Charcoal is somewhat brittle, but it doesn't just crumble, you need quite a lot of pressure to make it crumble. So just heating it will not make it disappear. It will shrink and develop cracks, but if any dust appears, it will still cling to the surface and fill these cracks, thanks to electric charges and microgravity. So before becoming dangerously deep, any cracks will fill with carbon dust, which will have even lower thermal conductivity.

And carbon doesn't melt easily... In fact it doesn't melt at all, it sublimates directly into a gas at about 4000K.

If we assume a wood wall thickness able to withstand stuff like micrometeorites, then having some thickness of the surface converted to charcoal will not make much difference to the wall integrity. If it did, the space station would already be destroyed just by space environment...

What this all means is, you will not be getting through by what is usually meant by "heating", exactly. You will be getting through by using laser cutting, probably vaporization cutting method, because that is the only way to get the material actually removed so you can keep cutting deeper.


Addenum: If instead of heating you are happy enough with burning through using chemicals, then Carbon will readily react with practically any reactive chemical, producing a lot of heat in the process too. This is well covered in other answers. But my impression from the question is, you don't want to burn the wood and produce the heat that way, you want to just heat the wood (maybe from a distance?).

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Right so there are actually several different questions here. If you apply direct thermal energy, such as an infrared laser to the hull without any oxidizers eventually the hull will heat to fracture as the particles gain too much energy to remain cohesive. Depending on the conductive properties of the material such heating may result in fire breaking out on the interior face of the area being heated. That's heating organics in a vacuum covered.

The weapon of choices depends on the desired outcome:
Direct heat as above.

If your attackers just want in considerably faster than direct heating they need to use a chemical attack, super-heating liquid oxygen, liquid ozone, or liquid fluorine and spraying the hull with it would get fairly instantaneous results as you're applying an oxidizer and a lot of energy to keep the reaction going, if want to savage anything of the ship later don't use the Fluorine, once it starts it doesn't stop reacting.

If you want to smash through the hull and dump the atmosphere with minimal collateral damage then you use a laser that's tuned to a much higher energy state and pump in ionizing radiation in the form of UV or Gamma, it will still cause the hull area under fire to fracture but without as much heating of the material thus reducing the area that burns when the atmosphere vents. This is going to take as long or longer than direct heating and a lot more power.

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    $\begingroup$ While super dangerous to the attacker, throwing a bottle of FOOF (infogalactic.com/info/Dioxygen_difluoride) at the ship's hull will have amazing effects. FOOF is so reactive it sets ice on fire, so the moment the liquid touches the wooden hull, spontaneous combustion will occur, even in the vacuum of space. $\endgroup$ – Thucydides Aug 1 '17 at 16:24
  • $\begingroup$ @Thucydides Yeah I didn't suggest that stuff because it's so hard to store and deploy safely. I'd super-heat to add reactivity to whatever was in use anyway, it also acts a heat-sink for the ship anyway. $\endgroup$ – Ash Aug 1 '17 at 17:46
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An ordinary oxy-acetylene torch will do quite nicely.

In cutting steel, the two gases are combined to form a flame hot enough to melt the steel and raise it to its kindling point.

At his point, the steel ignites in the flow of oxygen. The heat of this combustion is sufficient to heat more steel to ignition point, and so on. The flow of oxygen can be used to direct the path of steel burning, and the acetylene can be shut off.

Exactly the same process would work for wood, except that lower temperatures would be involved, and the melting step could be skipped...

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The wood will fail.

When (complex) organical matter is subjected to high temperature in the absence of oxygen or halogen (or any oxidizer for that matter) it'll decompose into smaller molecules since the big ones simply can't hold it together anymore.

I suggest reading this to get more insight of the process. Depending on how realistic you want to keep it you can play around with some interesting organic compounds. This doesn't work so well for metals though, but those will simply melt when heated just the same.

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In addition to the charing on the outside, mentioned in the other answers, the inside of the station will burn depending on how hot and for how long.

Although the outside of the station may be the other side of the wood and where the heat is applied, the energy will still be transfered, and may reasonably ignite as it hass access to oxygen.*

Alternatively, one could fire an oxidizing agent - for example nitric acid, at the hull, and it will burn perfectly well on the outside.

*Until a hull breach or vent at which point the inside will no longer have oxygen to burn with

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There are a number of hypergolic substances that will spontaneously ignite in contact with organic materials, potassium chlorate is one. There is another one, which I can't find at present, but has been described as being extremely hypergolic in contact with cotton or test scientists.

Spraying an appropriate material onto the wood should set fire to it, even in a vacuum, however the extreme cold of space might reduce the effect.

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If you want a conventional fire despite being in a vacuum, the attacker need only ignite an oxidizer (phosphorous, for example). There are probably numerous combinations that contain oxygen and reacts with heat, so there should be no shortage of options here.

Or, perhaps a bit less practical, a flamethrower that injects oxygen into the jet (like some welding techniques - so like a torch, essentially).

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