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Vacuum Rules

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Slith Slith's picture
Vacuum Rules
On pg. 201 under Vacuum: "Additionally, characters trapped in space without adequate thermal protection suffer 10 points of damage per minute from the extreme cold."

The thing is, space isn't cold. Or hot. It's simply nothing, a vacuum, an insulator. This passage was kind of like a curve-ball from nowhere because the entire first part of the Vacuum rule is pretty much completely accurate. [Although 1 minute is an extraordinarily long time to remain conscious in a vacuum. The average person today would only last 15-20 seconds consciously, with the onset of death [heart no longer beating] within 5 minutes... But I just chalk this up to transhumanism.]

In truth, it's the exact opposite of cold that is often the problem in space. Anything that produces a lot of heat - physical exertion, a high-energy power source, etc. Can very quickly overheat a person/vehicle/spaceship because the only way to transfer that heat energy away is through radiation. There is no convection or conduction.

Spacecraft deal with this primarily through very large radiator panels. A coolant of some type [Liquid sodium, lithium, water, etc.] is heated by the ship, then pumped to the radiators. This is of course subject to thermodynamic efficiencies.

I would heartily recommend reading the Atomic Rocket website; The author has put a lot of work into compiling information about space, spaceships, types of engines, warfare, etc. etc.

jackgraham jackgraham's picture
You're right on the
You're right on the temperature thing. In Earth orbit, cold is not a problem; a thermometer in Earth orbit reads around 40 degrees. Cold is an issue when you get farther out in the system (Belt & out).

I spent a bunch of time researching temps in various regions of space, effects of vacuum exposure on humans, and the like. A lot of it got cut due to space considerations -- but at least we avoided including the stupid explosive decompression mistake that some sci-fi makes.

Another problem: We originally had separate rules for asphyxia vs. drowning. The panic rules in the section on asphyxia (in the Combat chapter) should only apply to drowning. Panic due to drowning is caused by the same reflex that makes waterboarding such a nasty form of torture. This doesn't happen in airless environments, because the transhuman body's panic reaction only happens when it detects fluid in the airways.

So yeah, we did think of this stuff.

GMs who want to add more realism are encouraged to do their own research on this and find damage factors that work for them. What we ended up with in Core should suffice for people who are less obsessive than the poster & I. What can I say? We only had 400 pages. My numbers on what happens if you jump into a cryovolcano didn't make it in, either. :)

J A C K   G R A H A M :: Hooray for Earth!   http://eclipsephase.com :: twitter @jackgraham @faketsr :: Google+Jack Graham
puke puke's picture
this is something i'd be

this is something i'd be interested in learning a bit more about. i remember an old science class where we watched water simultaniously freeze and boil, just in the kind of vaccuum that we could pump with an air compressor and a bell-jar.

with that in mind, i always imagined that horrible things would happen (due to loss of pressure, not any kind of temperature change) to your eyes and capilaries. not to mention the oxygen and nitrogen in your blood seperating out, i.e. the bends.

can you point me at some of your research sources, so i can do some reading?


Slith Slith's picture
Well NASA's page on this is a
Well NASA's page on this is a good place to go for starters:
puke puke's picture
i read the bits on Atomic

i read the bits on Atomic Rocket a long time back, and the NASA article is interesting. it seems like the authors of the various scientific articles are downplaying the effects, but when you read between the lines its actually really severe.

the bends (aka decompression sickness) is listed as a minor side effect, though its something in its self that can be fatal. they suggest that the overall pressure in your blood stream will remain about the same, but then they admit that its the same overall, and that it relies on the expansion / vaporization of blood near the surface of the body to presurize the rest of the system. the common theme in several of the articles i've seen is a QA format where they posit the question "will your blood boil?" followed by a stern "no" and then a lengthy explaination of how most of your blood wont boil because is remaining presurized by the parts that did boil.

Lots of web pages are quoting 15 seconds of functional consiousness, but the only actual study i have found (Bioastronautics Data Book, Second edition, NASA SP-3006) cites 9-11 seconds of consiousness, of which about 5-10 seconds might be usefull.

a common side effect to exposure is listed as "blindness and other vision defects." even if it is sometimes recoverable, i wouldnt want to gamble on it. most subjects survive if repressurized within 60-90 seconds? i guess thats a lot of combat rounds, but it still sounds like pretty serious business to me.

I think most of this stuff is published by guys who have a strong interest in downplaying the dangers of space exploration. i dont blame them, its traditionally a hard sell to drum up funds for that sort of thing. but it seems to me like vaccuum exposure is no triffling problem.

Slith Slith's picture
I think the biggest reason
I think the biggest reason the NASA article downplays the effects of decompression sickness is simply due to the fact that by the time you're even feeling the bends in space, you're already dead.

The other problems, like blindness, might be a result of the bends, or the eyes freezing as the water on them boils away.
puke puke's picture
well they do say that the
well they do say that the blindness is neurological in nature and often quickly fades after represurization. so i guess it sort of puts to rest those nightmare visions of jagged shards of ice errupting out of your eyeball and tearing off your lense and cornia and etc. im sure glad THAT doesnt happen, even if some of your blood DOES boil.