Atmosphere

[greymankle]

I was wondering how the various homebrew Star Hero games out there explain artificial atmosphere. I am debating between a super-tech dome or terra forming the planet ala Firefly. It will be for a huge military installation on Pluto's Moon, and a hudson city clone on the surface of Pluto.

 

Dome seems more sci-fi but I can see it being a huge weakspot for the installation. Punch one hole and there goes everything.

 

Any other ideas, or comments?

[Cancer]

Re: Atmosphere

 

I think a dome is the "quick and easy" method, and uses the same sort of hand-wave technology you already have to posit for cheap, fast interstellar/interplanetary travel. You're right, punching a hole in the dome would be lethal, but all you have to do is use the same technology used to keep fist-size meteoroids from punching a hole clean through your spaceship as you go through space at exceedingly high speeds.

 

Terraforming a planet involves many orders of magnitude more material and more time, and you can only do it when both the surface gravity and the incoming stellar radiation is about the same as Earth's (and by "about the same" I'd guesstimate a factor of 3 to 5 ... the old game Spaceward Ho! used a factor of 2.5 for this, and that is actually probably a decent number). I.e., you could terraform Mars, but you couldn't terraform Pluto. But you could build a dome in either place.

[BlackSword]

Re: Atmosphere

 

I was wondering how the various homebrew Star Hero games out there explain artificial atmosphere. I am debating between a super-tech dome or terra forming the planet ala Firefly. It will be for a huge military installation on Pluto's Moon, and a hudson city clone on the surface of Pluto.

 

Dome seems more sci-fi but I can see it being a huge weakspot for the installation. Punch one hole and there goes everything.

 

Any other ideas, or comments?

I think the dome is the way to go. Likely the dome would be sectioned off into sectors so that if a hole appeared in one, it could be sealed off from the rest of the city. A super-tech dome could even be self healing. Also it would likely have some sort of point defense to protect it from incoming weapons or meteorites. Also, I have the feeling that a dome would be feel more gritty, which would be appropriate for Hudson city.

 

As Cancer said, Pluto is too far from the sun and too small to make terraforming anything but the rubberiest science.

[Nyrath]

Re: Atmosphere

 

Dome seems more sci-fi but I can see it being a huge weakspot for the installation. Punch one hole and there goes everything.

Well, it will take some time for the pressure loss to drop to dangerous levels.

 

whooshTime = ( gaspFactor * vol) / holeArea

where

gaspFactor = 1.4 for 80% pressure, 4.3 for 50% pressure, 29 for 1% pressure.

whooshTime = time for cabin pressure to drop to specified fraction of initial value (seconds)

vol = volume of air in the cabin (cubic yards)

holeArea = area of the breech (square inches)

 

So if a posh passenger cabin of 20 cubic yards has a one square inch hole blown in the bulkhead by a wayward meteor, the inhabitants have an entire 86 seconds (about a minute and a half) before the atmospheric pressure drops to one-half.

[AlHazred]

Re: Atmosphere

 

No way, man! I watch the movies - it takes much less time for this.

 

Unless... You don't suppose they might be inaccurate, do you?

 

 

[Less facetiously: Thanks, Nyrath! Always coming up with the hard numbers!]

[Lanith]

Re: Atmosphere

 

What about domes with energy fields to hold gasses/objects in like in Final Fantasy: Spirits Within?

 

Now you're only worry with those meteorites is them hitting a person/building/etc inside the city.

[Spence]

Re: Atmosphere

 

Dome seems more sci-fi but I can see it being a huge weakspot for the installation. Punch one hole and there goes everything.

 

Any other ideas, or comments?

 

Do a combo. The actual base is tunneled into the surface of the planet and/or uses many small heavily armored domes. The dome is the "civilian city" that has sprung up to service the military population. It started as a "temporary surface shelter" and grew. Since the civilian city was never actually planned it has a very nasty unseen criminal side. The base itself doesn't really care what happens in the city as long as it doesn't spill onto (into?) the base proper and the crimes involving service member doesn't get to far out of hand. In the event of enemy action the civilian city is basically on its own. If your tavern just happend to be built on the top of a planetary defence battery hidden silo, and you discover it when it deploys. Well you shouldn't have built there....

[austenandrews]

Re: Atmosphere

 

Frankly, on a rocky world far from a sun, there's no great urgency to build on the surface. Your best option is to go underground. Potential leak points are greatly reduced, and no artificial dome is going to protect better against meteors and radiation than a few hundred feet of stone. If you're determined to have a replica of a Terran city, gouge out a giant cavern and build the city inside it.

[Roy_The_Ruthles]

Re: Atmosphere

 

the "deep space radiation" near pluto causes the atmosphere of the moon to become ionized. While having no effect on breathablity, a highly advanced supercooled magnet could use magnetic forces to "pull" the air into the moon, keeping it from escaping. And if water splitters could produce water faster than the moon loses it, then the ionized theory cold work.

[Ternaugh]

Re: Atmosphere

 

the "deep space radiation" near pluto causes the atmosphere of the moon to become ionized. While having no effect on breathablity' date=' a highly advanced supercooled magnet could use magnetic forces to "pull" the air into the moon, keeping it from escaping. And if water splitters could produce water faster than the moon loses it, then the ionized theory cold work.[/quote']

 

Actually, I like the method used by Marc Miller in an article about Luna for Traveller (in an old Dragon magazine from the '80s). He had one installation that used focused grav generators to pull back the air molecules when they floated out of the protected zone.

 

JoeG

[Roy_The_Ruthles]

Re: Atmosphere

 

I had to say something besides the terraforming and the dome idea.

 

 

Maybe a really big net to catch the oxygen

[Nyrath]

Re: Atmosphere

 

In the golden age SF novels SEETEE SHIP and SEETEE SHOCK, Jack Williamson has planetary engineers using paragravity generators to give atmospheres to small asteroids. (Seetee is slang for "C.T" or "Contra-Terrene", an obsolete term for antimatter)

[Basil]

Re: Atmosphere

 

Well, it will take some time for the pressure loss to drop to dangerous levels.

 

whooshTime = ( gaspFactor * vol) / holeArea

where

gaspFactor = 1.4 for 80% pressure, 4.3 for 50% pressure, 29 for 1% pressure.

whooshTime = time for cabin pressure to drop to specified fraction of initial value (seconds)

vol = volume of air in the cabin (cubic yards)

holeArea = area of the breech (square inches)

 

So if a posh passenger cabin of 20 cubic yards has a one square inch hole blown in the bulkhead by a wayward meteor, the inhabitants have an entire 86 seconds (about a minute and a half) before the atmospheric pressure drops to one-half.

To go metric, use cubic meters, square centimeters, and multiply by 0.203.

 

BTW, a hemispherical dome with a radius of 8km will give a ground area about that of Hudson City. It'll have a volume of 1.072 * 10^12 cu. meters. A hole with a radius of 100 meters (which is pretty damned big) will be about 3.14 * 10^ 8 sq cm. This gives 762 seconds (12.7 minutes) to hit 80% pressure, more than 49.5 minutes to hit 50% pressure, and more than 5 1/2 hours to drop to 1% pressure.

 

Getting everyone out in 49-50 minutes would be hectic, but not impossible if the people train in emergency procedures. And as others have said, the place would be sure to be compartmentalized. I don't see "dome collapse" as something to worry about.

[Duke Bushido]

Re: Atmosphere

 

In our Sci-Fi campaigns, most airless outposts go underground as someone else mentioned earlier. Fewer worries about puncture, radiation, and irrecoverable heat loss. That, and it just seemed more practical from the POV of atmosphere scarcity. It seemed wastefull to fill with hard-won oxygen an area the bulk of which was totally unusable for inhabitation, whereas with a tunnel town, you only need to air where people are going to be.

 

Of course, if your campaign allows for cheap air or floating buildings or any of a hundred other things, then that 'empty space' may be quite practical.

 

Just tossing out ideas. Your world is your own, and bound to be different from ours, after all.

 

(And scenic skies would most likely make for better flavor text that do grey-walled warrens.....)

 

Duke

[Silversmith]

Re: Atmosphere

 

You might think about a series of domes for different neighborhoods connected by tunnels either under the surface or made of the same thing the domes are made from. You would reserve large domes for important areas of town. You could also have some neighborhoods under the surface and make them less well-to-do areas of town. The people who are wealthiest live under the domes with the less affluent living further from the surface.

 

As a side note there would be almost no light from the sun. It would look like a really bright star from Pluto. Did you have any ideas about artificial sources of light? Even street lights would make for one depressing place. (Yeah I know it's a game and you could ignore the problem with a lack of natural lighting contibuting to depression, but I might WANT to build a domed city on Pluto someday and need some ideas on how to handle this problem )

 

And as for air you could capture a comet (you are basically in the kuiper belt) and tap the water ice in it and break it down with electrolysis. Hydrogen (for fuel) and Oxygen. Then when you burn the hydrogen, thereby combining it with oxygen, you create more water.

 

Did I depart from the actual question enough? Sorry, I couldn't help myself.

[Spence]

Re: Atmosphere

 

You would reserve large domes for important areas of town. You could also have some neighborhoods under the surface and make them less well-to-do areas of town. The people who are wealthiest live under the domes with the less affluent living further from the surface.

 

 

 

I would actually make the underground the wealthy and well to do area and the domes the "slums".

 

Originally the domes housed the initial engineering crews and the pioneers. As they completed the underground tunnel/dome complexes the more influential and wealthy moved into the spacious and aesthetically pleasing Undercities. Broad, brightly lit underground passages connect separate industrial zones from the mild climate malls, housing districts and DomeParks. Surface structures and domes are left to the poor and the criminals. They have to make do with domes prone to leaking atmosphere, exposure to hard radiation and the occasional explosive decompression…

[Silversmith]

Re: Atmosphere

 

I would actually make the underground the wealthy and well to do area and the domes the "slums".

 

Originally the domes housed the initial engineering crews and the pioneers. As they completed the underground tunnel/dome complexes the more influential and wealthy moved into the spacious and aesthetically pleasing Undercities. Broad, brightly lit underground passages connect separate industrial zones from the mild climate malls, housing districts and DomeParks. Surface structures and domes are left to the poor and the criminals. They have to make do with domes prone to leaking atmosphere, exposure to hard radiation and the occasional explosive decompression…

 

 

Okay that works, too. I was thinking about the view available from the surface, not necessarily safety. You know, the same thing that make rich people in California live on the edge of a cliff instead of in a flat area not prone to mudslides.

[austenandrews]

Re: Atmosphere

 

If you go with a surface enclosure, a dome-shape may not be ideal. It has some strength advantages but unless you have a reason for all that open atmosphere, a shape with a lower profile may be more practical. Of course on a planet with 1/15 Earth gravity, a tall enclosure doesn't need to worry much about supporting its own weight. (A contemporary city on Pluto will look interesting. A mild breeze will blow street trash high into the air. A fit person will be able to jump from a fifth floor window without injury. A reasonably strong person will be able to bench press a modern car. In fact you could give all characters +20 STR to calculate jumping and lifting. A healthy cat might jump from street level to the roof of an eight story building.)

 

The "dome" could be built in multiple layers, sandwiching a high-tech gel between them. If a layer gets breached, the compromised gel closes up into a temporary seal. Noncompromised gel is electrically activated to harden for additional protection.

 

Or you could run with something more like Roy's net idea - instead of a rigid structure, how about a containment bubble kept aloft by air pressure? Wouldn't give as much protection against very high velocity impacts, but it may even be better for low speed hits. And the engineering would be greatly simplified.

[bigdamnhero]

Re: Atmosphere

 

In my games, terraforming is normally for worlds you want to colonize (ie - have people live and raise families on). Domes are mostly for:

1. A relatively quick and cheap interim step to terraforming, or

2. Worlds unsuittable for terraforming -- too small, too far/close to sun, etc -- but that still have some good reason for people to live there (scientific outposts, small mining settlements, covert military bases, etc).

 

Of course as with most such things, a lot depends on your assumptions about how many Earth-like and/or life-bearing planets are out there. If there are a lot of worlds that can sustain human life without terraforming, then there won't be much need to terraform any more.

 

I was thinking about the view available from the surface' date=' not necessarily safety. You know, the same thing that make rich people in California live on the edge of a cliff instead of in a flat area not prone to mudslides. [/quote']

Yeah, if past human history is any indication most people will choose scenic over safe any day. Besides, people in general just don't like living underground for long stretches of time. We were born in the trees and we like to see the sky...

 

Of course, that assumes the decision is up to them, not the corporation that built (or insures) the place.

 

Of course on a planet with 1/15 Earth gravity...A reasonably strong person will be able to bench press a modern car.

`Tho don't forget that that he can still be crushed if he drops the car: 1/15 gravity doesn't reduce its mass.

 

 

bigdamnhero

“I use the word “man†in its broadest possible sense. For as we all know, God made man in his own image. It’d be a sad lookout for Christians throughout the globe if God looked anything like you.â€

[Cancer]

Re: Atmosphere

 

Yeah' date=' if past human history is any indication most people will choose scenic over safe any day. Besides, people in general just don't like living underground for long stretches of time. We were born in the trees and we like to see the sky...[/quote']

 

I think that's correct, but the rich folks would still be underground if the underground quarters get scenery projected on the walls/ceilings, and the surface domes don't. There's no reason the dome material would be transparent, especially if it's cheaper and/or stronger when it's opaque.

 

We do know that exposed surfaces slowly accumulate crap on them (as well as getting micropitted), even in outer space. Washing the outer surface of a dome is probably Just Not Worth It, and repolishing/smoothing the outer surface even more so, so even an initially transparent dome would stop being transparent in a few centuries.

[Basil]

Re: Atmosphere

 

 

{snip}

Of course on a planet with 1/15 Earth gravity...A reasonably strong person will be able to bench press a modern car.

`Tho don't forget that that he can still be crushed if he drops the car: 1/15 gravity doesn't reduce its mass.

However, damage from something one is holding and drops on oneself depends on weight. Damage from something thrown at one depends on velocity and mass.

[austenandrews]

Re: Atmosphere

 

However' date=' damage from something one is holding and drops on oneself depends on [u']weight[/u]. Damage from something thrown at one depends on velocity and mass.

Exactly. Many cars would only weigh 200 pounds, which is not enough to crush an adult's skull or rib cage. Not that it'd be pleasant, but it wouldn't be fatal.

[Silversmith]

Re: Atmosphere

 

True but a car would not be practical in 1/15 gravity anyway. Not enough gravity to provide decent friction for rolling forward. Vehicles would probably travel on tracks where the passenger compartment was suspended between the tracks and would travel by magnetic propulsion (not dependent upon friction)

 

Apologies to the OP for the thread departing so far from the original question.

[austenandrews]

Re: Atmosphere

 

Apologies to the OP for the thread departing so far from the original question.

Not entirely OT for someone trying to put a modern city onto Pluto.

[tm80401]

Re: Atmosphere

 

You might think about a series of domes for different neighborhoods connected by tunnels either under the surface or made of the same thing the domes are made from. You would reserve large domes for important areas of town. You could also have some neighborhoods under the surface and make them less well-to-do areas of town. The people who are wealthiest live under the domes with the less affluent living further from the surface.

 

As a side note there would be almost no light from the sun. It would look like a really bright star from Pluto. Did you have any ideas about artificial sources of light? Even street lights would make for one depressing place. (Yeah I know it's a game and you could ignore the problem with a lack of natural lighting contibuting to depression, but I might WANT to build a domed city on Pluto someday and need some ideas on how to handle this problem )

 

And as for air you could capture a comet (you are basically in the kuiper belt) and tap the water ice in it and break it down with electrolysis. Hydrogen (for fuel) and Oxygen. Then when you burn the hydrogen, thereby combining it with oxygen, you create more water.

 

Did I depart from the actual question enough? Sorry, I couldn't help myself.

 

 

You would lose way too much energy in breaking down the water to Hydrogen and Oxygen for it to be worthwhile to burn the Hydrogen as a fuel. It would only work if you used the Hydrogen for Fusion power.