A Suffocating Problem ...

[rust]

My new science fiction setting needs a rule for suffocation, because the air on

the planet at the center of the setting is not breathable. The house rule I used

for previous settings is a bit too complex, and so I tried to find the relevant ru-

le in the BGB.

Looking at the spot rule for Choking, Drowning and Asphyxation on page 218, a

character takes damage to his hit points each round after he failed the last roll

of the series of CON rolls described there. The text then lists the damage for in-

haling water, smoke or poison gas, but I seem unable to find the amount of da-

mage caused by the lack of breathable atmosphere.

Any help with the rules or, if such a rule really does not exist, any idea for the

amount of damage taken in such a situation would be welcome.

[icebrand]

1D4!

[rust]

1D4!

The same damage as for inhaling smoke ?

Well, why not - bought.

As long as I can tell the players that this was discussed on the forum and is not my

arbitrary decision ...

[Thalaba]

2D4.

There. Now you can say both 1D4 and 2D4 were talked about, and you chose the lesser. That'll stop their whining!

[Agentorange]

Why isn't it breathable ? Simply not enough oxygen ? In which case 1D4 is ok.....but if it's toxic or superheated then more might be in order.

[rust]

Why isn't it breathable ? Simply not enough oxygen ?

No oxygen at all, the planet has the same kind of nitrogen - carbon dioxide atmo-

sphere which Earth had before oxygen producing algae developed. Theoretically

the carbon dioxide would be somewhat toxic, but someone attempting to breath

the atmosphere would suffocate because of the lack of oxygen long before the

carbon dioxide could do any significant harm.

[Skunkape]

Unless they were "oxygen producing algae"!

I'd go with 1d4 myself also!

[Atgxtg]

No oxygen at all, the planet has the same kind of nitrogen - carbon dioxide atmosphere...

Hey! You thief!! Swiping my Adnex setting!!! .

I'm going to half to be moe careful with my emails!

[quoute]

...which Earth had before oxygen producing algae developed. Theoretically

the carbon dioxide would be somewhat toxic, but someone attempting to breath

the atmosphere would suffocate because of the lack of oxygen long before the

carbon dioxide could do any significant harm.

[rust]

Hey! You thief!! Swiping my Adnex setting!!! .

I'm going to half to be moe careful with my emails!

Blame it on the planet Mars, he was the first one to use that idea ...

BTW, Will you be needing my notes for armored airships and carbon fiber pneumatic cannon?

Thank you very much for the offer, but they would not fit well into this setting.

It is one of my usual "colony settings", this time in a background universe with

reaction drive spaceships for interplanetary travel (which makes a voyage of a

year or so quite normal) and wormholes for interstellar travel. The planet at the

core of the setting is a somewhat Mars like desert world (yep, once more), only

a lot bigger, with a much more dense atmosphere and an acceptable surface

gravity.

The initial colony will be very small, only 250 people, and their equipment will be

not very futuristic, the most advanced technologies will be robotics (but robots

are still extremely dumb) and genetics (to create the lifeforms required for the

terraforming of the planet). From the "feel" of the setting this more "tilt rotor

aircraft territory" than "airship territory" - think 2300AD, perhaps.

[Atgxtg]

One of the reasons why I used airships was that there are actually quite good for this sort of setting. In a Nitrogen-Co" atmosphere, air would be a lifting gas, so any enclosed structure would be viable as a flyer. Carbon fiber frames and skins and pumps that would fliter air out of the CO2 would have a lot of advantages as a colony vessel. It is almost the idea vessel for such a setting.

But, what am I doing? I should kep my mouth shut and write up Adnex as a game setting!

BTW, Be careful how big you makeyou planet. Since you prefer a hard SF setting, you should be aware that as the size/gavitiy increases, the minimum molecular weight retained is lowered. So a big planet could hold oxygen or other lighter gases. A ntrogen-carbon atmosphere would suggest a low gravity.

[rust]

One of the reasons why I used airships was that there are actually quite good for this sort of setting. In a Nitrogen-Co" atmosphere, air would be a lifting gas, so any enclosed structure would be viable as a flyer. Carbon fiber frames and skins and pumps that would fliter air out of the CO2 would have a lot of advantages as a colony vessel. It is almost the idea vessel for such a setting.

True, and I would not rule out that the colonists could one day decide to build

an arship, it would indeed have many advantages - but exactly these advanta-

ges convinced me to keep an airship out of the characters' hands, at least du-

ring the early phase of the campaign. I want them to move on the ground and

to experience all the various natural hazards of the planet before I allow them

to get airborne and avoid the majority of these problems.

The colony therefore does have two shuttles for transports between the orbit

and the planet's surface, and it will have a few aircraft in the not so far future,

but these are not suitable for the kind of exploration missions the characters will

have to go on early in the campaign (not much ability to hover, and no ability to

land "in the wilds", etc.).

So, if the characters are clever and fast learners and ask for an airship, they will

almost certainly get one sooner or later - but they have to come up with that

idea.

BTW, Be careful how big you makeyou planet. Since you prefer a hard SF setting, you should be aware that as the size/gavitiy increases, the minimum molecular weight retained is lowered. So a big planet could hold oxygen or other lighter gases. A ntrogen-carbon atmosphere would suggest a low gravity.

Yep, I basically used the early Earth as the model for the planet, and just remo-

ved almost all of the water, otherwise it has almost exactly the same properties

as our planet did before life developed. I wanted to have reliable, "hard" data,

and the best source seemed to be the very distant past of our own planet.

[Conrad]

BTW, Be careful how big you makeyou planet. Since you prefer a hard SF setting, you should be aware that as the size/gavitiy increases, the minimum molecular weight retained is lowered. So a big planet could hold oxygen or other lighter gases. A ntrogen-carbon atmosphere would suggest a low gravity.

Not necessarily. Remember that oxygen is a highly reactive gas, so if there are no indigenous lifeforms that are producing it, then it will combine with other elements such as iron, as it has done on Mars to form....rust!

As for Rust's atmosphere I'd use 1d8 for damage and use the asphyxiation rules (CON X 10 if not surprized by the event of the exposure to the atmosphere) and since there is no oxygen to be had CON X 3 if a failure occurs on the earlier roll or if surprized by exposure to the atmosphere.

Edited June 24, 2011 by Conrad

[rust]

Not necessarily. Remember that oxygen is a highly reactive gas, so if there are no indigenous lifeforms that are producing it, then it will combine with other elements such as iron, as it has done on Mars to form....rust!

Yep, I will be all over the place in this setting ...

[Conrad]

My new science fiction setting needs a rule for suffocation, because the air on

the planet at the center of the setting is not breathable. The house rule I used

for previous settings is a bit too complex, and so I tried to find the relevant ru-

le in the BGB.

Any help with the rules or, if such a rule really does not exist, any idea for the

amount of damage taken in such a situation would be welcome.

If anyone wants some rules on atmospheric damages I've just posted some in my blog on this site.

http://basicroleplaying.com/entry.php/66-Atmospheric-damage-rules.

Edited June 30, 2011 by Conrad

[rust]

Thank you very much.

After a few quick calculations a damage of 1d8 per round seems a bit much for

the situation.

I would expect that most characters would fail one of the first ten CON rolls. If

they make it to the first CON x 1 roll, they have held their breath for 10 rounds

or 2 minutes. With a damage of 1d4 they would then take an average damage of

2.5 per round, so a normal person with 12 hit points would fall unconscious and

die after about another 5 rounds = 1 minute, after holding the breath for a total

of about 3 minutes, which seems to fit well with real world data.

With a damage of 1d8 after the first failed CON roll the person would suffer an

average damage of 4.5 per round, so a normal person with 12 hit points would

fall unconscious and begin to die after 3 rounds = 36 seconds, after holding the

breath for a total of about 2 1/2 minutes, which seems a bit too short.

[Atgxtg]

Not necessarily. Remember that oxygen is a highly reactive gas, so if there are no indigenous lifeforms that are producing it, then it will combine with other elements such as iron, as it has done on Mars to form....rust!

Yeah, but it isn't just oxygen you have to worry about. As the gravity increases the planet is able to retain lighter elements, not just oxygen. So Nitrogen-CO2 becomes less likely. Eventually you reach a point where the planet is mostly hydrogen.

[Conrad]

Yeah, but it isn't just oxygen you have to worry about. As the gravity increases the planet is able to retain lighter elements, not just oxygen. So Nitrogen-CO2 becomes less likely. Eventually you reach a point where the planet is mostly hydrogen.

If a world can hold hydrogen to some extent and there is some oxygen present then you've got water. This doesn't stop a nitrogen and carbon dioxide atmosphere forming as Mars had, and probably still has, plenty of water locked up in permafrost. Nitrogen is fairly unreactive and CO2 is produced by vulcanism so the rationale for having such an atmosphere isn't too improbable.Higher planetary gravities and higher minimum molecular weights retained doesn't stop elements like oxygen from combining with other elements, and being taken out of the atmosphere. In fact the more elements retained the more chance that these elements may react with any free oxygen (apart from the noble gases).

Edited June 24, 2011 by Conrad

[Atgxtg]

If a world can hold hydrogen to some extent and there is some oxygen present then you've got water. This doesn't stop a nitrogen and carbon dioxide atmosphere forming as Mars had, and probably still has, plenty of water locked up in permafrost. Nitrogen is fairly unreactive and CO2 is produced by vulcanism so the rationale for having such an atmosphere isn't too improbable.

Yeah, it does. What you are failing to see is that water is heavier that hydrogen or oxygen.

If you look at Earth,m we have no hydrogen to speak up. Yes, we have a lot of water, but any free hydorgen would escape the Earth gravitational pull.

Look up Minimum Molecular Weight Retained to see what I am getting at.

It is why all the big planets are hydrogen gas giants.

[rust]

Yeah, but it isn't just oxygen you have to worry about. As the gravity increases the planet is able to retain lighter elements, not just oxygen. So Nitrogen-CO2 becomes less likely. Eventually you reach a point where the planet is mostly hydrogen.

While this is true, a planet with a high enough surface gravity to retain a size-

able amount of free hydrogen long enough that it is still there when the planet

has cooled down enough that humans could theoretically want to terraform it

and live there would have a too high surface gravity for humans anyway - if it

is cold enough to live there and still has lots of free hydrogen in its atmosphere,

you would not really want to go there.

[Atgxtg]

While this is true, a planet with a high enough surface gravity to retain a size-

able amount of free hydrogen long enough that it is still there when the planet

has cooled down enough that humans could theoretically want to terraform it

and live there would have a too high surface gravity for humans anyway - if it

is cold enough to live there and still has lots of free hydrogen in its atmosphere,

you would not really want to go there.

Sure. I didn't say the planet had to be small. I only warend against making it too big. There is also a time factor, too. Earth way like that when it was forming, but probably couldn't be that way now.

With that in mind, one thing that could make a planet very interesting to scientists would be if it were inexplicably younger than it should be. Such would either be taken as evident against the Big Bang theory,or evidence that someone out there can make planets.

[Conrad]

Yeah, it does. What you are failing to see is that water is heavier that hydrogen or oxygen.

If you look at Earth,m we have no hydrogen to speak up. Yes, we have a lot of water, but any free hydorgen would escape the Earth gravitational pull.

Look up Minimum Molecular Weight Retained to see what I am getting at.

It is why all the big planets are hydrogen gas giants.

No, I'm not failing to see that water is heavier than both hydrogen and oxygen. That is just basic science. You're also telling me lots of things I already know, like minimum molecular weights. I'm also saying that with more elements retained in an atmosphere there is more chance of oxygen reacting with those elements and therefore it will not be in a breathable form(e.g. CO2, CO, FeO etc).

What I'm saying, and you're failing to acknowledge is that Rust's atmosphere can form on a largeish terrestrial world. That a gas giant world will have more hydrogen and lighter elements retained is basic knowlege. We aren't talking gas giant worlds here, Rust's world is clearly terrestrial.

Edited June 30, 2011 by Conrad

[Conrad]

There is also a time factor, too. Earth way like that when it was forming, but probably couldn't be that way now.

I agree. Its life that has changed the atmosphere on this world. Without it we'd probably have an atmosphere that is very like Mars or Venus. Being nearer to the sun than Mars, and having lots of CO2 in the atmosphere would eventually bake the Earth in that case.

Edited June 25, 2011 by Conrad

[rust]

To give some numbers, Samar has a diameter of 15,028 km and a surface gravity

of 0.94 g (it has a lower density than Earth, the iron core is smaller and the hea-

vy elements are more rare). This makes it much bigger than Mars, which probably

was the remark that caused some confusion, but only slightly bigger than Earth.

[Conrad]

If you are going to get into the details of your creation Rust, then what type of star does it circle and how many AU is it from that star? What is the axial tilt? Does it have a magnetic field? Moons? How many gigayears old is your planet? What other worlds are there in the system?

Edited June 25, 2011 by Conrad

[rust]

If you are going to get into the details of your creation Rust, then what type of star does it circle and how many AU is it from that star? What is the axial tilt? Does it have a magnetic field? Moons? How many gigayears old is your planet? What other worlds are there in the system?

I have those data, but in German. It should be easy in most cases to see what is

meant, but you may have to use an online translator now and then:

The star Turan:

Typ: F9 V

Alter: 3,85 Milliarden Jahre

Masse: 1,15

Temperatur: 6.100 K

Leuchtkraft: 2,09

Radius: 0,006 AU

The planet Samar:

Jahreslänge: 676,46 Tage

Tageslänge: 19,34 Stunden

Achsneigung: 7 Grad

Durchmesser: 15.028 km

Umfang: 47.188 km

Oberfläche: 709 Mio. qkm

Schwerkraft: 0,94 G

Atmosphäre: Stickstoff-Kohlendioxid-Atmosphäre

Hydrographie: 0 % (Aquifere und Polare Eiskappen)

Klima : Durchschnittstemperatur 12° C

Geländeformen: Felswüste, Sandwüste, Gebirge

Vulkanismus: Gemäßigt

Tektonik: Gering

Rohstoffe: Kristalle, Leichtmetalle (Aluminium, Titan)

Biosphäre: keine einheimischen Lebensformen, Bioterraforming

The other planets:

Alpha Orbit 0,32 AU

Heiße Felswelt, Durchmesser 6.210 km

keine Atmosphäre, kein Wasser

kein Mond

Beta Orbit 0,55 AU

Ödwelt, Durchmesser 9.490 km

keine Atmosphäre, kein Wasser

2 Monde

Gamma Orbit 0,93 AU

Treibhauswelt, Durchmesser 14.340 km

sehr dichte toxische Atmosphäre, kein Wasser

1 Mond

Samar Orbit 1,58 AU

Wüstenplanet, Durchmesser 15.028 km

exotische Atmosphäre, polare Eiskappen und Aquifere

Kolonie seit 2376, Terraformingprogramm

kein Mond

Epsilon Orbit 2,69 AU

Kalte Felswelt, Durchmesser 5.830 km

keine Atmosphäre, polare Eiskappen

1 Mond

Zeta Orbit 4,57 AU

Kalte Felswelt, Durchmesser 4.750 km

keine Atmosphäre, kein Wasser

3 Monde

Eta Orbit 7,78 AU

Kleiner Gasriese, Durchmesser 48.500 km

4 große Monde, 13 kleine Monde

Theta Orbit 13,23 AU

Eiswelt, Durchmesser 2.070 km

keine Atmosphäre, eisbedeckt

kein Mond

Wormhole Orbit 36,59 AU

Zielsystem Recalada, Dauer des Transits 3 Tage

A planetologist was so kind to take a look at the data, so they should be close enough to rea-

listic data for my purposes.

Some other data, for example concerning the magnetosphere, are more hidden in the descrip-

tive text, so I do not post them here.

Edited June 25, 2011 by rust