How to survive a fire in microgravity....

StilLearning

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#1
Hey everyone, and thanks in advance for your thoughts. My ongoing project is a document to help authors who want to write some (just some!) realistic physics into their science fiction - think the kind of thing 'The Expanse' did. This is something I already do in-person for a few authors, since I've got good qualifications in physics (including one specifically in space technology), and my day-job is a physics and maths tutor. They've encouraged me to put this together but I've really struggled with finding a clear, accessible, structure: Some people I've run this past want just a very quick rundown of the facts, some want details of the science, some find humour more accessible/more annoying, and some want just pure description, or an example. Because of this the structure I've hit upon, finally, is five subsections per chapter: A fact sheet, a prose section explaining the science, a first person descriptive (almost flash fiction) of what it is / would be like in real life, a worksheet, and list of sources of information.

What I've put here is parts of chapter 5: The factsheet, a sample of the science-explaining prose, and a sample of the descriptive/flash fic. The actual sections are about 4 x as long as the chunks I've posted here. I've omitted the worksheet and list of sources to try and keep this post from being unreadably long. I'm looking for any and all feedback, and if anyone wants to see more of a section, or the worksheet or sources list (I have links to some astronauts describing real-life space near disasters, but have to be careful what I use directly due to copyright!) feel free to PM me.

5: How would astronauts fight fire in weightlessness?

Fact sheet:
  • Most fire in space is diffuse, less aggressive, but almost invisible.
  • Some liquid fuels continue burning after flames are extinguished, via an unknown mechanism.
  • Lithium perchlorate canisters - a common part of life support systems - burn with an intesne, bright flame.
  • Weightless fires are tough:
    • They needs less oxygen and fuel to survive, resisting smothering.
    • If starved of oxygen or fuel they break into pinhead-like flamelets, which spread and replicate until they find a new supply.
  • Smoke in spacecraft spreads and builds rapidly, blinding and suffocating even people far away.
  • Venting atmosphere can put out fires, but this can mementarily whip a fire into a blowtorch like flame.
  • Space stations and ships only carry light fire fighting equipment: Extinguishers and ventilator masks.
  • In microgravity fire extinguishers throw the user around (cheers Newton).
  • The recommended response to a fire is:
    • All crew immediately put on oxygen masks.
    • Shut down ventilation to reduce oxygen flow and contain smoke.
    • Shut off electrical power to the burning region.
    • Tackle the fire using appropriate extinguishers (CO2, water mist or foam).
    • Close off the affected compartment if possible.
  • Prep for evacuation
The science:
Being stuck in a kitchen with a burning toaster is, I once discovered, fairly terrifying. Being in a burning building… well that’s why we have heroic people called ‘the fire service’ who do the ‘save you from a burning building’ thing. But imagine a situation where there’s no fire brigade, the burning building is hermetically sealed, and escaping outside will actually kill you faster than the fire will.
Welcome to firefighting in space. No-one being able to hear you scream is your smallest problem.
Astronaut crews have almost nowhere to run from a fire, and no-one to help them. Tackling a blaze means using whatever equipment they have to hand – on present day space stations that’s just fire extinguishers and ventilator masks. In some space capsules, like the Russian's Soyuz, it’s... well, nothing. But since headlines like ‘Right Stuff Astronauts Die in Space Fire’ don’t sit well with space agencies (and even less so with the right stuff astronauts), preventing and stopping fires in space has become the subject of specialised, very well sealed, in-space experiments. What they've shown is that microgravity fire is a different creature – less aggressive but deceptive, and more adaptable – thanks to the way gas flow changes in weightlessness: On Earth hot air rises in a quick moving column, pulling the flame into a relatively well confined, bright, cone. In weightlessness hot air spreads slowly and diffusely, so flame spreads diffusely, diluting the light it emits – it can become almost undetectable, except in near darkness. The lack of well defined air flow also changes how fast the heat in burning material dissipates, how waste products spread out, and how fires consume oxygen. As a result weightless fires use both less oxygen and less fuel, stay burning at lower temperatures, and are tougher to put out than their gravity bound kin. That lesser appetite can make them less aggressive - but they’re also less predictable: Terrestrial fire always spreads upward faster than any other direction, but when there’s no ‘up’ it spreads randomly....

The experience:

.....I tumble through a hatch and into the hazed air of the station’s core module, a water-foam fire extinguisher clutched in one hand - I barely recall tearing it free from it's wall mounting as I hurled myself through the station's structure. A few meters further along the roughly cuboid living space I spot mission commander Ivonova hovering in the physics lab hatchway, struggling with a small CO2 fire extinguisher’s release catch. An odd, orange-white, glow illuminates her face from inside the lab, and tendrils of more opaque smoke are already reaching out of the meter wide opening. Holding a paper towel from the cleaning kit over my nose and mouth, I pull myself along the off-white wall towards her via cable bundles and locker handles. She snags the bulkier water-foam extinguisher from me, floats it next to her in the hatch, and finally gets her CO2 extingiusher to fire into the burning lab. The snatching motion turns me in midair, and for a second I see:
...John Sheridan, half dressed and face pale, swearing as he flings any flammable objects away from the lab hatch...
...Payload specialist and pilot Ashifa Naseer pulling a ventilator over her head, grabbing onto a worksation with one leg and, incongrously, starting to print something - trajectory data for an emergency flight home I guess – even as sparks fly past her face....
....‘Mickey’ Garibaldi’s hanging in the hatch leading to the hydroponics lab, shouting to Ivanka Iordanaova behind him: “'Vanka grab the ventilators and bolt cutters; We gotta fire!“
My spin brings me back around and, as I grab one of the thick bundles of cable running through the hatch to steady myself I realise we’re going to need Ashifa’s re-entry trajectory: Ivonova’s struggling - in microgravity the extinguisher’s kick demands she use one had to grab the edge of the hatch, making aiming it almost impossible. It’s hard to track the diffuse flames that form in space, they could be...
 

Brian G Turner

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#2
I really like the factsheet and objective descriptions - this is intriguing and engaging stuff. I would definitely read more of this.

The fiction that follows comes across as unnecessary padding. Additionally, the names are based on Babylon 5 characters, so it comes across as fanfic. :)

My personal suggestion would be to focus on the educational element, and let our minds wander with that. If you use it as a vehicle for fiction you may find things get muddled up, not least your initial objectives.

2c.
 

StilLearning

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#3
Thanks Brian G Turner, that reflects my own thoughts (the babylon 5 names are placeholders - I'm terrible at figuring out names so it's always one of the last things I do, sorry about that), but I'm very much told that for this to be of use to a writer there needs to be a very strong element that is descriptive of the human experience of these things. To do that I think I need a framing mechanism. I get consistent negative feedback about mixing it in with the science: People who want the science complain it distracts from the science, people who want the descriptive stuff tell me the science gets in the way. That's a big part of the thing that's kept this project as just a word doc for two years - I don't suppose you've got any suggestions? If I can't figure it out by christmas I plan to either drop the descriptive stuff entirely or confine it to a few passages in text boxes placed about the pages.
 

CTRandall

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#4
Great stuff! I agree that the first, factual section was more interesting for me. The structure of fact sheet followed by descriptive paragraphs on the science works well. Like Brian, the sample fiction bit did less for me, though the realistic approach to tasks (printing re-entry data instead of fighting the fire) was also informative. Lists of sources for more in-depth info would be great (I know you left them off for the word count).

I would definitely read more of this. It would be great to have it online as a general web resource (though that might obliterate any possibility of you making a deserved income from your work).
 

The Judge

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#6
Wow! I read the fact sheet and the science bit and I actually understood it all! Since I failed my chemistry mock O-level -- the only exam in my life I've ever failed, if we exclude the first ignominious driving test -- and only just scraped through with it and physics at the real thing, that should help confirm this standard is fine for science ignoramuses. So get on and do the rest. (And perhaps somewhere explain what microgravity means... :p)

Nit-picking-wise there are quite a few typos, so do make sure you check through thoroughly to sort them out or get someone to do line-by-line editing for you. For the science bit, I'd suggest chopping it up into smaller paragraphs for easier reading, and when posting here always remember the clear line's space between paragraphs, which you might also need if you do put this online -- though I, too, think you should do it in book form and get some recompense for the splendid work.

I'm also of the don't-mix-the-science-and-story opinion, as it would just muddy the water for both scientists and non-scientists. Personally, I didn't feel the need for the whole "experience" bit, and I find it a bit bewildering that a would-be writer has so little imagination that he/she needs a great deal more than the notes you've given.

Having said that, a bit of extra detail in the science bit wouldn't go amiss -- eg this line "The lack of well defined air flow also changes how fast the heat in burning material dissipates, how waste products spread out, and how fires consume oxygen" is crying out for examples of the differences, and eg it would help to know which extinguisher to use for which situation -- but I appreciate you could well have written those bits and just not included them here for space reasons. Though I'm not sure something four times as long as this section would hit the mark either -- you've got to keep the non-specialist's attention, and the longer something is, the more danger of losing readers at the outset. It might be an idea to let us have a full-sized version of another bit (in another thread, I think) so we can see if it's bordering on too much, or, contrariwise, whether yet more info would be helpful

If you do feel you need some more descriptive elements based on other feedback, I don't think creating a piece of fiction is the best way of going about it, since you'll inevitably get would-be writers criticising your prose rather than noticing the science (sorry, I can't help it... ;)). My suggestion would be to have something like this -- which could well be what you've got for your worksheet, in which case, I think that's enough:

What does this mean for a writer?
  • the air will be hazy, which means poor visibility and coughing/choking. Get masks on everyone asap and perhaps invent some goggles enabling them to see better through the mist, perhaps even helping see the flamelets
  • the fires will be orange-white, not red or blue, and have that reflected on surfaces, which will cause more confusion about locating the real flames
  • no matter how well-trained, crew members are going to be scared -- show that in how they react to the fire and each other eg yelling, eg fumbling for catches on the extinguisher
  • the crew will be clumsy, and the slightest knock will have them spinning round, and if they don't want to be blasted backwards, they'll need to hold onto something before using the extinguishers -- perhaps invent some that can be fired accurately one-handed
  • someone should be throwing all potentially flammable objects well out the way or into flame-proof cupboards/boxes; someone else should get bolt cutters to cut stuff [I've no idea what!!] away
  • perhaps have someone calculating trajectory data for emergency flights home and/or prepping life pods
I've done it as bullet points, but you could just have easily amalgamated it into a short paragraph.

Hope that helps a bit. In any event, good luck with it!
 

Joshua Jones

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#7
I will join in with everyone else here and say the fictional aspects are superfluous, but the science is really interesting. Truth be told, it is actually immediately relevant to my WiP, so thank you!

I also disagree with those who have told you that writers would need the fictionalized element to humanize it. At least regarding SFF writers, we tend to have pretty decent imaginations, so we shouldn't have too much of a problem finding ways to adapt this information. Where we tend to struggle a but more is on the science side, as most of us are more studied in English composition and creative writing that physics and chemistry. So, I think there could be a good market for a reference book which addresses science questions in the context of SF. But, your primary market for such a work would be writers, not readers (though there are surely some readers who would pick it up!).
 

StilLearning

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#8
Thank you everyone - I am up to my neck in non writing problems until Wednesday night, but as soon as I can I'll get back with a proper response. This has been really good feedback so far and given me a good sense of where to head, especially TJ's suggestion on an alternative way of doing descriptive stuff - I'm very grateful to everyone!
 

StilLearning

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#9
I may start a different thread (in a few days when I've got a chance to do a proper spell check and read through) with a more complete science section - everyone seems to agree that's the part to focus on, and I'd be interested to see how people reacted to a fuller example of it., and get feel for if more or less information is more helpful. Do people have an opinion if it make sense to use the whole science subsection of this chapter or a different one? I am slightly inclined towards this one, as it's relevant to Joshua Joe's WIP and that feels like killing two birds with one stone (space fires have other tricks they can play, and space craft and stations have been redesigned to help with firefighting).
 

Joshua Jones

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#11
I suggested another one so we could assess it without being influenced by what we've already learned here. (Plus we get more freebie info! :p) But if it'll help Joshua, go with a longer version of this one.
No, by all means, let's get more freebie information! :)My question is pretty well answered, and the rewrite of the scene is underway.

Got anything on shockwaves and equations for figuring out their effective range? If not, I'll take whatever you have and gleefully incorporate it.
 

StilLearning

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#12
No, by all means, let's get more freebie information... .
A whole chapter on supernova blast radius, but it's a mess and I'd need to clean it for a few days. Rough rule for radiation pulses and shockwaves: doubling the distance cuts the force/energy delivered by a factor of four, tripling it cuts the power by nine, quadrupling by sixteen, etc. Inverse square law, if your not familiar with it, is the best term to google. Applies to 3d shock waves, pulses, and emissions in space, those on a planets surface are more complicated.
 

Joshua Jones

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#13
A whole chapter on supernova blast radius, but it's a mess and I'd need to clean it for a few days. Rough rule for radiation pulses and shockwaves: doubling the distance cuts the force/energy delivered by a factor of four, tripling it cuts the power by nine, quadrupling by sixteen, etc. Inverse square law, if your not familiar with it, is the best term to google. Applies to 3d shock waves, pulses, and emissions in space, those on a planets surface are more complicated.
Sounds pretty straightforward. That will definitely be useful when I am calculating the effects of ships exploding in orbit. I may be able to model some of the damage as well...

My immediate use is actually for shockwaves in atmosphere. I briefly mentioned a shockwave cannon in my 75 word entry; it is intended to be an anti-personnel weapon which uses concussive forces, powered by shaped charges and compressed air, to kill rather than projectiles, and is mounted on a powered body armor. I have a rough idea of how much strain the armor could withstand, but I am trying to work out how far of an effective range it would have without causing self-harm. So, what does the equation look like in earthlike atmosphere?
 
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StilLearning

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#14
It sounds a little like a very high powered sonic cannon, which isn't designed to kill but does use a lower power form of atmospheric shock wave, sound, so I would think the maths would be similar in crude outline. Does that sound at all plausible? They have been deployed in real life: G20 protesters blasted by sonic cannon. Killing range would depend on the angle of the beam and power, though with high explosive replacing speakers I can only really guess what the source power would be as it would depend on charge type and size. How much range does your plot need?
 

StilLearning

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#15
When I say 'angle of the beam' I mean angular width from edge to edge. If your shock wave beam forms a cone with, say, a 20 degree angle at the tip then the power decreases as the surface area of a slice through that cone increases. So once you are far enough down the cone to have increased the surface area of the slice by four times your power per area of human body it delivers drops by a factor of four. So it depends on how focused the cannon beam is, and what the explosives powering it are. This being Sci fi I suggest that you start with plot requirements and then set the beams angular width and source power to whatever they need to be - explosives technology is always being advanced. You could even used something very exotic like antimatter explosives if your plot will allow it, which would allow a very compact design with truly tiny explosive charges.
 

Joshua Jones

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#18
There isn't exactly a specific plot need for range; I made an initial prediction of 0-10 meters for door breaching, 20-40 meters for a kill range, 40-80 meters for stun/blowback, and 80+ for the crowd control sonic cannon effects (although, they would not likely be used in crowd control anyway). The unit is designed as a shock troop, to be applied in ship boarding, urban combat, and assaulting industrial structures, so the limited range isn't a particular drawback (and they also have a secondary weapon for longer ranges). But I wanted to confirm the recoil strain on the suit based on these estimates, and then I got thinking about the possibility of my estimates being low... so, that is the basis of my question. I am trying to establish a range of plausibility, so I can determine what they would likely construct.

It sounds like, though, my estimates would not really require a particularly strong explosive charge. Which is good, as it increases the amount of ammunition they could realistically carry. Is this a fair assessment?
 
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