View Single Post
Old 06-24-2013, 09:21 AM   #1
vicky_molokh
GURPS FAQ Keeper
 
vicky_molokh's Avatar
 
Join Date: Mar 2006
Location: Kyïv, Ukraine
Default Reconciling Martian and Terran environmental needs

Greetings, all!

So, long story short, our team decided to live on the same space station as the little dragons*. But there's a complication. All of our bodies are meant for a Terran environment (disregarding issues of gravity). The little dragons, OTOH, are Mars-Adapted without the ability to handle a Terran environment. Specifically, the limits of their zone of comfort are 0.6 bar of pressure and +10°C / 283K / +50°F (degrees Fahrenheit). Sure, we have a sealed compartment where we can keep a Terran atmosphere for complete comfort, but we'd rather prefer to be able to share the rest of the station with them too, without denying either the humans or the dragons the ability to fly around without a vacc suit. There are two sides to reconciliation, and I have some doubts and ambiguities about both.

1. A mid-way environment.
The default Martian atmosphere has either 0.4bar, and one of: 45% carbon dioxide, 27% oxygen, 21% nitrogen, 2% argon, 5% other; OR 75% CO2, 15% O2, 5% N2, 2% Ar, 3% others.
That puts partial oxygen pressure at somewhere between 0.1 bar absolute and 0.06 bar absolute. Luckily, the dragons are okay with reducing CO2 and upping O2 to human levels. The question is, how much? The total atmospheric pressure pretty much has to be set to 0.6 bar, which counts as Thin for us, but as still okay for them. For us, a Thin atmosphere means a -1 to Vision, +1 to FP costs, and rolls for altitude sickness if we stay for 60+ minutes in the low-pressure section of the base. But that's assuming an Earthlike percentage of O2, i.e. about 21% of total pressure, which amounts to a partial pressure of 0.126 bar absolute. But this can be upped.

(Edit: we can lower CO2 to human levels, so it's not an issue.)

What are the nuances of upping partial pressure of O2 in a low-pressure atmosphere?
GURPS says that 0.8 bar at Earthlike composition, or 0.168 bar absolute partial pressure of O2 specifically, is the lower range of the human-normal O2 level. Wikipedia lists 0.16 bar absolute as the lower okay limit of partial pressure. So, should upping the partial pressure to this level (thus resulting in about 27% oxygen) get rid of the altitude sickness, the FP cost, and the Vision penalty? Or will the Vision penalty stay? Is such a relative percentage of O2 okay, or does it have some sort of threat?

Luckily, the human temperature zone in GURPS is considered to reach as low as 2°C / 275K / 35°F (degrees Fahrenheit). I guess it's somewhat (by about 10°C) optimistic, but hey, maybe it just assumes the humans are northerners - after all, it puts the upper human limit at 32°C / 305K / 90°F (degrees Fahrenheit), which seems pessimistic by almost the same 10°C.

2. Biomodification.
Full-scale biomodification is mostly out of the question: they're built such that we can't grant them temperature tolerance at all, and lung modifications would only expand their zone of comfort by 0.2 bar at most. They've also been through some other major trauma recently, so we're disinclined to put them through anything stressful at all.
Likewise, none of us is inclined to install the full Mars-Adapted biomod. First, there's the issue of straining points (we're trying to mostly avoid Mutable Point Totals), but also of monetary costs and recovery times. Also, Low-Pressure Lungs are sort of nasty when used in 1-bar atmo.

Now, Pressure-Tolerant Lungs (Perks, p.11) are totally awesome, since the perk allows a human to treat Thin atmospheres as Normal, but Normal as Normal too, all things being equal. Which is awesome, since it seems to solve the partial pressure problem all on its own. But this Perk was published waaaay later than all of THS biomods, or even the 4e Bio-Tech biomods. So I'm unsure if it's possible to get it, and how. Yes, I know it's borderline useless for a real Martian atmosphere, but for the midway environment, it seems like a perfect fit. Do you think it's an available biomod in THS, and should it be a difficult one if it is?

Thanks in advance!

* == a curiosity of a bioengineering design.
__________________
Vicky 'Molokh', GURPS FAQ and uFAQ Keeper

Last edited by vicky_molokh; 06-24-2013 at 12:57 PM.
vicky_molokh is offline   Reply With Quote