Odd question about terraforming Mars

[Junghalli]

For the Martian atmosphere and hydrosphere, you aren't necessarily restricted to what's already on Mars. The outer solar system has plenty of ices; you could create a tailor-made atmosphere and hydrosphere if you needed or wanted to.

One possible issue is the amount of CO2 needed to create the necessary greenhouse effect. Faint sun paradox solution calculations suggest an atmosphere with thousands of times present CO2 (>10% of the present atmosphere) to keep early Earth warm with 2/3 our present sunlight (the early sun was dimmer than it is today). Here's a paper for reference. Mars recieves less than half our sunlight. It may be possible to create a warm Mars with an atmosphere rich in both oxygen and CO2, but baseline humans could not breathe such an atmosphere - CO2 is poisonous to us at such levels.

One possibility is to use a different greenhouse gas. For instance, this site lists hydrofluorocarbons as having "global warming potential: 4,000 to 10,000 times that of CO2", so even trace concentrations could create an enormous greenhouse effect. Another possible solution is to use orbiting mirrors to concentrate more sunlight onto Mars, giving it a roughly Earthlike energy balance.

What seems to be the most cost effective solution in the longer run :

- Adapt a whole planet to human needs by using some technology very near from magitech we could only dream about today (atmospheric change, soil adaptation, etc.).
or
- Adapt humans to live in harsh condition using science, technology and biology (bio-domes, subterranean habitats, genetic engineering, etc.)

Colonizing Mars with enclosed artificial habitats would probably be a lot easier than terraforming. It's a simple question of scale. Creating an enclosed habitat requires creating and sustaining an artificial environment on a relatively small scale, and repeating the process over however many habitats. Terraforming essentially means doing the same thing, only on a scale many orders of magnitude larger, and probably with much less precise control (it'd probably be a lot harder to adjust the climate, air etc. over a planet than in a small habitat). In terms of the amount of environment that must be re-engineered, enclosed habitats are much more efficient, and present much less problem of scale. This is, of course, a naive analysis (the two challenges are really very different in detail), but I think the essential comparison can still be made.

Actually adapting a human to survive on the surface of Mars as it is today without protection ... that would be very difficult. IIRC water won't even stay liquid on Mars because of the low pressure - your Martian would have to be covered with some kind of biological pressure suit, or (probably even harder) you'd have to somehow engineer a physiology that could function without water, at which point you're basically redesigning life from scratch.

The problem I have with orbitals isn't physical, it's social. Orbitals require tight social controls to function, as well as tight physical controls. A terraformed planet at least theoretically offers the option of being able to move away from aspects of the local society you don't like on a small budget. An orbital doesn't, unless space travel is made very, very cheap.

On another board I remember Destructionator mentioning that travel within a close cluster of habitats might not be very difficult at all; your spacecraft could just be an airtight box that's launched by the habitat's own rotation and drifts over until it's snagged by another one (I forget all the specifics). At any rate, even rockets could probably be a lot cheaper between habitats than surface to orbit. Getting between habitats in similar orbits probably wouldn't take much delta V, so no need for staging, and no need to worry about having enough thrust to fight gravity, or the stresses of atmospheric re-entry ... a strictly habitat to habitat ship would be a lot easier to build than a surface-orbit-surface ship.

[Simon_Jester]

Even in space, at Mars distances from the Sun? It's not like a ship; there won't be any fleshy bodies or engines* onboard to produce heat.

It'll be in direct sunlight, soaking up something on the order of 500 to 600 watts per square meter, much of the time.

You can maintain cryogenics in space, naturally; chemical rockets do so routinely. But it's not trivial and it does require ongoing consumption of power. Also a certain amount of structural strength: if you place magnetic coils in vacuum and use them to exert magnetic force on the solar wind, they will feel forces in the opposite direction pushing them around. You need mechanical strength and station-keeping thrusters to hold them in place.

It might be a viable solution for all I know; I've never heard it proposed before and I don't know what to think about it.

* Presumably they could be kept in proper position by their own power - doubling as magnetic sails - or by lightsails.

That won't work well, because to do their job they must push the solar wind away from the planet. That inevitably pushes them away from where you want them.

[Rabid]

So, if I may summarize...

You can get a Mars with an atmosphere of 100-300 hectopascals (0.1-0.3 bar), composed mostly of oxygen and nitrogen (or any gas that fit the same role as nitrogen), with important traces of CFC to have an average temperature of -20 /-10 °C (-4 / 14 °F).
That leaves us a thin but breathable atmosphere in which a human could survive without horrible difficulties, with a bit of technology (breather mask and a good parka) or with a shit-tonne of genetic engineering if you feel like it.

To obtain this atmosphere, you can dump some comets on the planet, melt the ice caps, throw in some genetically engineered bacteria / nanorobots to turn the various ice-stuff and rock-stuff into useful stuff, and mine the various fluorite of the Martian environment to mass-produce CFC (you won't get an Ozone Layer with that, I think...).

So there you have a planet with an atmosphere, but now you have to engineer a complete biosphere, or else in a millenia or ten all the Oxygen will be fixed back on the Martian rocks (ferro-oxidization AKA rust) and you'll have to do it all again.
And you'll hit a wall at first while trying to create a biosphere when you'll realize that Mars soil is highly toxic to terrestrial usual lifeforms, so you'll have to treat Mars soils before being able to, say, plant trees or crops, even reasonably genetically engineered.

Do I miss something ?

[Broomstick]

I come down on the side of overblown, but with a kernel of truth. If you're in an environment where the actions of one person can spell disaster or death of the group then there must be stronger social controls if the group is to survive.

Yeah, but unless that one person has a nuclear bomb, he can't really spell disaster for the whole group.

It depends on how big the habitat is, doesn't it? The smaller the habitat the more fragile it is.

Bad enough if someone shoots himself in the head - worse if by doing so he causes a major hull breach in a space habitat.

That's horribly unrealistic.

OK, so I exaggerated a bit. How about someone making a crude pipe bomb and blowing themselves up, breaching the hull, causing environmental problems, etc.

Someone going wild and free with big military weapons, tanks, missiles, battleships, shit like that could make trouble happen really fast. But if you pass a law prohibiting private ownership of operational battleship guns, I don't think it would affect very many people's lives!

Yeah, sort of the point - you don't need draconian controls to maintain reasonable safety in a large habitat.

Most the environmental regulations, for regular people, would probably be similar to what we have today. Don't start forest fires, don't burn toxic shit in your back yard, don't litter, that kind of thing.

It would have to be either stricter, better enforced, or both. A space habitat is a small, closed system, there's less room to dilute and mitigate environmental contamination and negative effects.

One thing did just come to my mind though: what if you turned on a hose in your yard, and left it there? If water pooled around the inner hull, that might be a problem. (though there's feet of earth between you and there, so it shouldn't be a big deal most the time). Perhaps the hab will include underground ditches to catch and reclaim it in these scenarios. Though this is a potential thing to regulate too. The easiest way seems to me to be to just charge for water like we do today, to discourage excess use. Problem solved, at least in likely practical terms.

There are, occasionally, people in the real world who more or less do that - turn on the backyard hose and leave it going, damn the cost, and it can have serious consequences for neighbors due to flooding, damage to building foundations, etc. Of course, we have courts, community, and police who can step in and force the water to stop - and I would imagine that any space habitat would have the same. The same controls we have on a planet. In other words, no more or less extreme than what we currently have.

[someone_else]

It depends on how big the habitat is, doesn't it? The smaller the habitat the more fragile it is.

Too small habitats are unpratical on purely mechanical reasons.
It must be big enough to avoid the need to balance it when people move around while it is spinning (and it will spin for a long time of its service life).
Otherwise you need to place ballasts and stuff to compensate and it's a pain.
Anything massive enough to avoid that problem has a population close to a thousand at least.

It would have to be either stricter, better enforced, or both. A space habitat is a small, closed system, there's less room to dilute and mitigate environmental contamination and negative effects.

A space habitat is a compartimentalized system. Forget all those "open space" cylinders where people live on ground-like areas and private homes mimicking US suburbs.
Overly inefficient disposition. That will be the "pubblic park" area at best. Maybe with some farms.
The people will inhabit apartments and flats in its "underground" levels. Which if you think about it, isn't terribly different from New York anyway.

This more than likely means that the section where the moron is burning shit will be immediately sealed shut and powerful vents that were used to move normal air through the "air conditioning" will move toxic fumes away. We can do it with tunnels and chemical labs, we can do it in space too.
And obviously, since the area has been shut closed, finding the moron is easy.

Also, there will be much more peer pressure, but that's true of any shared-ownership structure anyway.

How about someone making a crude pipe bomb and blowing themselves up, breaching the hull, causing environmental problems, etc.

Is that different from a kamikaze here on Earth?
Since the sections can be sealed, the damage dealt is limited. And if they don't guard a few sensitive areas like life support machinery, they deserve it imho.

If water pooled around the inner hull, that might be a problem. Perhaps the hab will include underground ditches to catch and reclaim it in these scenarios.

Any place where you have plants must have a decent draining system, otherwise roots rot away. Wondering why most pots have a hole in the bottom?

So, if I may summarize...

More or less... and in the same time with the same expenditure you can probably set up a dyson sphere. Not the shell kind, the "swarm of orbiting stations" kind.

The outer solar system has plenty of ices; you could create a tailor-made atmosphere and hydrosphere if you needed or wanted to.

Yes, if you can shovel hundreds of trillions of tons of ices from planets located 20+ AUs from here. (Oort cloud is much farther than that)
Btw, has anyone an idea of the weight of a human-breathable atmosphere on Mars?
I did some overly eyeballed calcs in the past, but... yeah.

One possibility is to use a different greenhouse gas.

Interesting. So, civilizations that have such capability can use CFC or similar instead of unbreathable levels of CO2.
I totally forgot about such chemicals!

Colonizing Mars with enclosed artificial habitats would probably be a lot easier than terraforming.

But much worse than building an orbital station and sharing the same drawbacks.

your Martian would have to be covered with some kind of biological pressure suit

Human skin is enough. Look for the mechanical pressure suits. It's drinking and eating that will be a major problem.

At any rate, even rockets could probably be a lot cheaper between habitats than surface to orbit.

Are you kidding me right? They ARE a lot cheaper , since they require at best 4-5 km/s of delta-v, while liftoff from Earth is well above 10 km/s of delta-v.
Chemical rockets feel at home with such performance requirements. NERVAs are overkill.

[Broomstick]

It would have to be either stricter, better enforced, or both. A space habitat is a small, closed system, there's less room to dilute and mitigate environmental contamination and negative effects.

A space habitat is a compartimentalized system. Forget all those "open space" cylinders where people live on ground-like areas and private homes mimicking US suburbs.
Overly inefficient disposition. That will be the "pubblic park" area at best. Maybe with some farms.
The people will inhabit apartments and flats in its "underground" levels. Which if you think about it, isn't terribly different from New York anyway.

This more than likely means that the section where the moron is burning shit will be immediately sealed shut and powerful vents that were used to move normal air through the "air conditioning" will move toxic fumes away. We can do it with tunnels and chemical labs, we can do it in space too.
And obviously, since the area has been shut closed, finding the moron is easy.

There are several possible scenarios here. One is the careless/stupid scenario where yes, the damage would remain compartmentalized (one hopes). There would still be damage and loss (up to an including human life) but it would be contained and limited.

Then there is the malicious/terrorist scenario where there is an intelligent agency deliberately planning harm, and potentially for worst-case scenarios. That is more likely to affect multiple compartments, defeat/go around safety systems, and cause wide-spread destruction.

How about someone making a crude pipe bomb and blowing themselves up, breaching the hull, causing environmental problems, etc.

Is that different from a kamikaze here on Earth?
Since the sections can be sealed, the damage dealt is limited. And if they don't guard a few sensitive areas like life support machinery, they deserve it imho.

Right - one or a few discontents disabling safety systems and everyone else - potentially thousands - somehow deserves the result.

Because aviation security didn't stop 19 guys on September 11, 2001 did thousands deserve to die in NYC, and more still at the Pentagon and in the field where the 4th plane crashed?

If someone is acting with malice they may be able to defeat safeguards that are adequate for accidents.

If water pooled around the inner hull, that might be a problem. Perhaps the hab will include underground ditches to catch and reclaim it in these scenarios.

Any place where you have plants must have a decent draining system, otherwise roots rot away. Wondering why most pots have a hole in the bottom?

A drainage system adequate for normal use by be defeated by abnormal circumstances. Hell, when I set up my hydroponics last week we spent hours on adjusting the drainage system, as compared to 15 minutes on the input pumps.

Your live support system has to be robust enough to handle unusual circumstances. I think that is well within human capability, but the issue with malice defeating normal safeguards would still apply.

One possibility is to use a different greenhouse gas.

Interesting. So, civilizations that have such capability can use CFC or similar instead of unbreathable levels of CO2.
I totally forgot about such chemicals!

You still need adequate partial pressure of oxygen, low enough concentrations of toxic gases like CO2[/b], and the remainder filled up with something inert. Nitrogen would get my vote, but you need a source of nitrogen to inject into the atmosphere. Even with a .5 bar atmosphere (which is probably the minimum required for long term survival) that's a LOT of N.

Colonizing Mars with enclosed artificial habitats would probably be a lot easier than terraforming.

But much worse than building an orbital station and sharing the same drawbacks.

I would expect similar technology to be used for both. Mars does have some resources, if it's cost-effective to extract them and launch them into space then Mars will be colonized.

One advantage Mars does have is that you don't need to spin anything for gravity. Whether 1/3 g is sufficient for long term human health is an unanswered question, however.

[someone_else]

I doubt efficiency in terms of people per square meter is a big concern. If you pack people in, you increase the risks of things going wrong - there's less of a buffer for error. If the population density is too high, it becomes impossible for natural processes to maintain things; you've gotta add a lot of machinery. This is likely to increase the total cost, and having less land per person is likely to decrease the amount they are willing to pay.

Having a biological ecosystem is completely out of question imho. Each person requires a prohibitive amount of biomass and surface if you use plants. With that surface and mass you can have much more redundancy in your machinery and more free space to run around the station and do more interesting things.
There will be plants and stuff but only for recreation imho.

The price depends much more from what you can do from that position, and since there is no good reason to go in space at all, let alone getting in a place where liberalists (liberitarian? whatever ) will feel in Soviet Russia, the prices will be pretty low.

Realistically, the entire space colonization thing does not pay for itself. Whatever will make us start colonizing will keep the prices high enough to turn a profit.

imho if the life support isn't distributed, you're doing it wrong anyway. Another advantage of the open air habs - no single point of failure.

While Earth's ecosystem can indeed ignore a lot of abuse, a space station's cannot since it is much smaller.
Forest fires? Tree illnesses? Some idiot burning enough chemicals to poison enough plants?
Tree that decide to die for no apparent reason?

Sometimes having a few well-defined points of failure allows you to keep an eye and correct the issue fast enough to prevent deaths.
Fixing a failing biological ecosystem isn't a joke, and it isn't anywhere near fast.

I keep prefering machinery.

Then there is the malicious/terrorist scenario where there is an intelligent agency deliberately planning harm, and potentially for worst-case scenarios. That is more likely to affect multiple compartments, defeat/go around safety systems, and cause wide-spread destruction.

Is that different from a bunch of terrorists bombing the sewer treatment plants of a city here on Earth? Or the major power lines for it? Or the major internet backbones to it? It becomes uhinhabitable fast. (without cheap internet porn for sure )

I mean, is that hard? I've yet to see anyone patrolling them on Earth.

If every section is more or less indipendent and sealable (this also helps when building it, since it's a copy-paste of the same design), they will have to do a huge amount of work to ensure a real catastrophe. The more is the work, the more chances you have to find and jail them.

Also, since you are either in orbit around Earth or there are stations nearby, escape pods are an obvious choice for these situations. And much faster than evacuating most cities on Earth.

Right - one or a few discontents disabling safety systems and everyone else - potentially thousands - somehow deserves the result.

The point is how a few discontents manage to fuck up a whole orbital hab with thousands of people on it?
Yes, that applies to 9/11 too.
I mean, fighting coordinated and well-funded intelligent threats (9/11 terrorists weren't beggars with C4, they were professionists) it's mostly an Intelligence Agency thing, and that isn't different from Earth surface.

If you let terrorists run around unguarded, no city is safe, in orbit or not. Maybe orbital stations are even safer, since sections can be sealed (a big FUCK YOU!! to chemical, biological and radioactive attacks), and can be designed to be evacuated fast.

Mars does have some resources, if it's cost-effective to extract them and launch them into space then Mars will be colonized.

So far, only platinum-group metals have any value (rare earths, used mostly in electronics). And they are much easier to get from asteroids. Or from asteroids that fell on the moon, that is also a pretty strategic source of rocket fuel.

But who knows.

One advantage Mars does have is that you don't need to spin anything for gravity. Whether 1/3 g is sufficient for long term human health is an unanswered question, however.

As if spinning things was hard.
One BIG disadvantage is that its atmosphere can carry away heat by conduction, wich is much faster than radiating it in vacuum.
This means you will have to use proper insulation.
There are also dust storms, or CO2 snow on your exposed equipment.
Another BIG disadvantage is that requires more than 5 km/s of delta-v to escape its gravity well (I say more since there is gravitiational drag).

And the rest of the problems of space stations we are already duscussing.

[Uncluttered]

Terraforming a whole planet seems rather excessive.

The world-roof concept seems more plausible to me. "Domes" of glass and/or plastic are stitched together over time to cover the entire useful planetary surface.

You can still have domes over shallow seas by sinking pylons into them. Many of the unmanned biospheres can be held up by atmospheric pressures alone.

The "Domes" have some clear advantages.
1. No risk of planet wide OOOPs. Remember that terraforming will be experimental, and mistakes can and will happen.
2. The worldhouse can be fit over any small planetary body. You can dome over Ceres if you choose.
3. Domes provide protection against radiation and micrometeorites.
4. Domes can keep large portions of Mars "Wild", so future generations can enjoy the natural mars.
5. Domes have shorter payoff time. You can use a dome right after you built it.
6. Domes scale better with price at lower populations. You can build a dome(s) to the size you need, and then add on as you grow. Terraforming becomes cost effective only when your population gets into the millions.....need to find my citations for this last point...
7. Domes do not remove your terraforming option, should you decide to use it.
8. Domes can act as energy gathering surfaces. I.E. transparent photovoltaics.
9. Domes can have different biomes and seasonal cycles.
10. Domes can be built on the ground, without needing an extensive orbital contruction industry. I feel this is important to mention, because colonization of mars from a seed colony, might never create the infrastructure needed to drag comets around the solar system. Labor, human and robotic, can be used to build domes from domestic mars sources.

[Broomstick]

I doubt efficiency in terms of people per square meter is a big concern. If you pack people in, you increase the risks of things going wrong - there's less of a buffer for error. If the population density is too high, it becomes impossible for natural processes to maintain things; you've gotta add a lot of machinery. This is likely to increase the total cost, and having less land per person is likely to decrease the amount they are willing to pay.

Having a biological ecosystem is completely out of question imho. Each person requires a prohibitive amount of biomass and surface if you use plants. With that surface and mass you can have much more redundancy in your machinery and more free space to run around the station and do more interesting things.
There will be plants and stuff but only for recreation imho.

Nonesense. You can utilize plants that serve multiple functions. All green plants will convert some CO2 to O2. It will almost certainly not be enough to do the entire job, but having even a portion of that conversion is probably a good thing, and would extend your buffer in the event your normal air recycling system is having problems. Many ornamentals can also be eaten. Having living plants around, and fresh green stuff to eat, provides a psychological as well as nutritional benefit.

So your park can have fruit trees (they'll need some artificial fertilizing, most likely) as well as various ornamentals that double as vegetables (rainbow chard, for instance, or the ornamental kales which remain entirely edible). People may well want to grow herbs in their living and working areas. There might be room for pure ornamentals such as flowers, but there's no reason you can't grow plants for parks and the like AND eat them as well.

Any civilization capable of building orbitals is capable of building small "pods" for hyro or aeroponics that will grow plants in small spaces with minimal use of water and other resources. We have that right now: behold the Aerogarden. Honestly that could be produced at a much cheaper rate than depicted, and with higher quality. Stick these all over living and working quarters, have strips of plants in major corridors... you could grow a lot of stuff in an orbital with a little imagination. Back up CO2 to O2 conversion, supplemental and back up food supply, psychological benefits - what's not to like?

Then there is the malicious/terrorist scenario where there is an intelligent agency deliberately planning harm, and potentially for worst-case scenarios. That is more likely to affect multiple compartments, defeat/go around safety systems, and cause wide-spread destruction.

Is that different from a bunch of terrorists bombing the sewer treatment plants of a city here on Earth? Or the major power lines for it? Or the major internet backbones to it? It becomes uhinhabitable fast. (without cheap internet porn for sure )

I mean, is that hard? I've yet to see anyone patrolling them on Earth.

Actually, the Chicago sewer system DOES employ guards on the main treatment plant. Armed guards, in fact, along with a secure fence. My own sewer system, alas, is unguarded - but then it's a septic system for this building and only this building, so it's a pretty small target. We still get our water tested regularly, though, just in case we wind up with ground contamination. Major powerline facilities are secured with fences... and the fact that screwing around with high voltage can kill the curious and/or malicious.

But, you know, with an open environment like the Earth's surface the situation is quite different. If the power grid goes down most people on Earth will be inconvenienced, but not really in danger. On an orbital, though, a power failure can be lethal. If your air recycling system is entirely power-dependent lack of power will kill you. If it is completely independent of power, like on Earth, you never worry about getting enough air. If you have mostly power-dependent air recycling BUT enough green growing things to act as a temporary back up you'll have more time to make repairs before you have to abandon a habitat. That's why size matters.

That's true of any system on Earth vs. on an orbital. The Earth's hydrological cycle runs without us, with both plants and soil providing filtration and purification to greater or lesser degrees that allows us to not be compelled to build expensive, power hungry machines to deal with every bit of sewage. You'd need a fucking huge habitat to allow even back-up or supplemental sewage treatment. In any case, on Earth water falls from the sky, we don't require pumps to move every drop.

And so on, and so on...

If every section is more or less indipendent and sealable (this also helps when building it, since it's a copy-paste of the same design), they will have to do a huge amount of work to ensure a real catastrophe. The more is the work, the more chances you have to find and jail them.

No disputing that. It's an obvious technique.

Also, since you are either in orbit around Earth or there are stations nearby, escape pods are an obvious choice for these situations. And much faster than evacuating most cities on Earth.

Of course escape pods need to be built, supplied, maintained... another one of those good safety systems, but not without some cost. Also, they won't be as useful in more remote colonies.

I mean, fighting coordinated and well-funded intelligent threats (9/11 terrorists weren't beggars with C4, they were professionists) it's mostly an Intelligence Agency thing, and that isn't different from Earth surface.

That doesn't mean the victims of such an attack deserve to die, which is what you implied.

If you let terrorists run around unguarded, no city is safe, in orbit or not.

Nobody "lets" known terrorists run around - the problem is that you won't know who they are until they do something - and if they are successful the first time then people suffer or die.

One advantage Mars does have is that you don't need to spin anything for gravity. Whether 1/3 g is sufficient for long term human health is an unanswered question, however.

As if spinning things was hard.
One BIG disadvantage is that its atmosphere can carry away heat by conduction, wich is much faster than radiating it in vacuum.

An atmosphere thick enough to support human life will also tend to moderate temperature extremes, so a planetary surface will never get as cold (or potentially as hot) as an object in vacuum at the same distance from the sun. So the problem of heat conduction is offset by less need for heating and cooling.

There are also dust storms, or CO2 snow on your exposed equipment.

And in space you have micrometerorites, not so micrometerorites, radiation, and so forth.

Another BIG disadvantage is that requires more than 5 km/s of delta-v to escape its gravity well (I say more since there is gravitiational drag).

Yes, that is a disadvantage of planetary surfaces.

[someone_else]

You can utilize plants that serve multiple functions.

To act as a backup that must keep people alive for anything more than a few hours, the plants must be enough to keep them alive indefinetly, and that is pretty space-hungry.
If instead of wasting space in plants you place backups of your critical equipment, k-rations and oxygen pressure tanks, you don't have to worry about failures threatening your well being.
They occupy much less space, which is the reason I'm using machinery. I can place much more backups in much less space. Wich means much more safety.

Biological ecosystems start to get way safer IF big enough, like planetwide (if the idiots don't pollute too much), but on any realistic-sized station (at best a few hundred km wide in the habitable section) you don't have all the surface needed to make an ecosystem anywhere as big, thus fault-tolerant, as a planet. Ecosystems don't scale down well.
If you have a Ringworld or a Dyson shell (that isn't torn apart by its own gravity), then yes, ecosystems are a far better choice.

Oxygen in pressure tanks also helps in case you need to vent some of the atmosphere in space or there is a hole, since machinery recycles wastes, but doesn't create oxygen out of pure energy.
Having some tanks of nitrogen would help a lot too.

Anyway, just to clarify, in the "mechanical systems" I include algae tanks with waste reclamation systems. Yeah, I know it is wrong, but I tend to mentally classify algaes as "machine" more than "plant".

building small "pods" for hyro or aeroponics

While that is awesome for food production, I wouldn't say it is a much safer system than what I'm talking about. You are adding a whole bunch of machinery to keep plants alive. If the "plant support system" fails you're screwed. Then you will need backups to the backups.

Major powerline facilities are secured with fences... and the fact that screwing around with high voltage can kill the curious and/or malicious.

Secured with fences? You need active security to stop an intelligent threat (like a guy cutting them or climbing them). Anyway, to take down the average power line you don't need to get anywhere close to the cables. Demolition charges or thermite-like stuff on the truss tower will take it down, with the cables, in complete safety for the malicious guy.
I think power lines on Earth are so ill-defended since it isn't so critical. Most hospitals or places that need power have backup generators anyway.

On an orbital, though, a power failure can be lethal. If your air recycling system is entirely power-dependent lack of power will kill you.

Well, if each air recycling system has double or triple redundancy and you have dispersed power generation, the odds of enough power plants (or life support) to doom you suddenly fail together are rather low.
It's more likely to die all by collective heart attack.
That's all costs and mainteneace rising, I know. But plants must be baysitted too or the station's ecosystem goes wrong. And they are no less cheap.

Also, without power nothing will manage heat distribution anymore. Something will melt and something else will freeze.
The solution is more or less the same as on Earth today. Multiple power plants not operating at anywhere near full capacity, able to compensate eventual losses or provide spikes of power when needed.

That's true of any system on Earth vs. on an orbital.

Uhm. In my previous posts I was making comparisons with Earth mostly for social issues. But this seems like a misunderstanding.
I'm not advocating orbitals as better than Earth.
Earth remains the cheapest, easiest although maybe not the safest solution to human habitation (you know, disasters like floods, tsunaims and hurricanes/tornaodes or earthquakes, random diseases and the odd volcano we lose millions each year for them).

But if for some yet unknown reason we may decide to colonize the solar system, then orbitals remain the most cost-effective idea. Imho of course .
So the comparison would have to be with a domed city or a terraformed planet.
It's plain obvious Earth wins hands down in this contest.

Of course escape pods need to be built, supplied, maintained... another one of those good safety systems, but not without some cost. Also, they won't be as useful in more remote colonies.

If you have the level of space exploitation needed to build anything at all in space, an escape pod is trivial to do. Still, that society has a money and people to spare for that.
Air Force and Navy, and most tank and artillery divisions are useless on an orbital, ICBM silos are overkill in space, and most civilian vehicles are not needed at all (freeing up most people usually working on them here on Earth).
I question the need for "remote colonies". Earth orbital space is mindboggingly HUGE, why for the Emperor's sake are you building a colony in any other place?
Mining? Bots can do that, slower but orders of magnitude cheaper.
Industry? Maybe. Most industry will be in Earth orbit though, simply beacuse it is vastly cheaper to ship ores than to bring workers far.
Scientific research? This is the only very good reason to stay far for a long time. If only Titan had something resembling alien life...

That doesn't mean the victims of such an attack deserve to die, which is what you implied.

That statement holds true if you are acting alone, taking responsibility for your actions. If someone else is responsible for your safety, then matters get more complex, but the general idea is the same. If they as a whole don't take the fuss of having a decent security in critical areas (wich means asking just that to their politicians), then they shouldn't be amazed that a couple ill-equipped dissidents blew up everything.

Nobody "lets" known terrorists run around - the problem is that you won't know who they are until they do something - and if they are successful the first time then people suffer or die.

That's why an intelligence agency exists, they look if people start doing suspicious activities by infiltrating suspicious organizations and keeping good information networks. A lot of terrorist cells were stopped and arrested before they were able to do any real damage.

Being just reactive is ok for law enforcement, but not for an intelligence agency. They exist to be one step ahead of the threats and prevent them before they do any harm.
You can look at what CIA and FBI did in the past.
No civilization can survive without an intelligence agency/secret services/ninja/Chuck Norris, because human intelligence can only be fought effectively with human intelligence. Or maybe with AIs or advanced expert systems in the future.

An atmosphere thick enough to support human life will also tend to moderate temperature extremes,

I think this comes from the same misunderstanding as above. This is true, but only Earth has an atmosphere with those requirements.
Pretty much any other planet requires you to build an atmosphere like that from scratch, while what is already there either cools you down fast or heats you up fast.
Placing some space radiators is trivial in comparison.

And in space you have micrometerorites, not so micrometerorites, radiation, and so forth.

Micrometeorites aren't a huge problem for a so big space station, bigger stuff can be detected easily and shot onto with lasers to deviate its course, asteroids can hit a planet much more easily than a space station.
Radiation is the same in orbit as on the surface of most other celestial bodies.
Well, maybe not on venus or gas giants, but those have worse problems.
But I still hope GCR dose can be safely compensated by human body unaided. There is people living in pretty irradiated environments without bad effects.
Then you just have to shield for solar activity, which is much less.

Domes provide protection against radiation and micrometeorites.

Well, to provide enough radiation protection as Earth they either need an artifical magnetic field that can be used on space stations too or have so much mass on them to be effectively underground.

Domes can keep large portions of Mars "Wild", so future generations can enjoy the natural mars.

I've never seen domes as a way to let people enjoy the "natural mars" if they want. But the idea merits some credit. That will surely attract more tourists than a terraformed mars.

Domes can act as energy gathering surfaces. I.E. transparent photovoltaics.

Beware of dust storms.

Overall I agree with the other points you make.
Domes are a good choice, while terraforming doesn't seem to be a choice at all.

[Broomstick]

You can utilize plants that serve multiple functions.

To act as a backup that must keep people alive for anything more than a few hours, the plants must be enough to keep them alive indefinetly, and that is pretty space-hungry.
If instead of wasting space in plants you place backups of your critical equipment, k-rations and oxygen pressure tanks, you don't have to worry about failures threatening your well being.

Nonetheless, a few hours might be critical in an emergency. Unlike oxygen under pressure (which, yes, you'll have anyway for storage), plants do not explode. The plants aren't your only back up, just one of many.

As for k-rations... you misunderstand. The plants are really emergency food stores (though they could act in that role) so much as on-going diet supplement. Eating fresh food is unequivocally beneficial to humans for both physical and psychological reasons. All too many people dreaming of pie-in-the-sky space settlements forget that.

Anyway, just to clarify, in the "mechanical systems" I include algae tanks with waste reclamation systems. Yeah, I know it is wrong, but I tend to mentally classify algaes as "machine" more than "plant".

Tough shit - it's a plant. Hypocritical of you to advocate machinery then use algae.

building small "pods" for hyro or aeroponics

While that is awesome for food production, I wouldn't say it is a much safer system than what I'm talking about. You are adding a whole bunch of machinery to keep plants alive. If the "plant support system" fails you're screwed. Then you will need backups to the backups. [/quote]
You'll need triple redundancy, at least, on a lot of systems in an orbital. Plants can survive for awhile if their "pod" malfunctions. It's unlikely that most orbitals will be self-supportive in food production, more likely there would be orbitals set aside as food factories (which might have a sufficient plant to people ratio that the plants COULD provide all oxygen needed, though you'd still want backup systems) with others having incidental food production. This would be analogous to city dwellers have small gardens, but relying on agricultural land for the bulk of their food.

Major powerline facilities are secured with fences... and the fact that screwing around with high voltage can kill the curious and/or malicious.

Secured with fences? You need active security to stop an intelligent threat (like a guy cutting them or climbing them). [/quote]
Not really - the last few idiots in my area who climbed high voltage tower literally fried. The fence keeps out animals and causal idiots. The high voltage tends to take care of the rest. Of course, when it does there's a tendency for them to disrupt power transmission, which is inconvenient and why we install fences.

I think power lines on Earth are so ill-defended since it isn't so critical. Most hospitals or places that need power have backup generators anyway.

And no doubt you'd have such back up supply for critical areas on an orbital as well. Which is one of my points, that you'll have multiple back up systems.

That's true of any system on Earth vs. on an orbital.

Uhm. In my previous posts I was making comparisons with Earth mostly for social issues. But this seems like a misunderstanding.
I'm not advocating orbitals as better than Earth.

But you seem to advocate them over a terraformed planet.

But if for some yet unknown reason we may decide to colonize the solar system, then orbitals remain the most cost-effective idea.

A lot depends on WHY we're colonizing space, though. That will affect how many orbitals, and where they are.

Of course escape pods need to be built, supplied, maintained... another one of those good safety systems, but not without some cost. Also, they won't be as useful in more remote colonies.

If you have the level of space exploitation needed to build anything at all in space, an escape pod is trivial to do. Still, that society has a money and people to spare for that.

But sufficient escape pods for a population in the thousands will take up enormous space, even if resources are plentiful.

I question the need for "remote colonies". Earth orbital space is mindboggingly HUGE, why for the Emperor's sake are you building a colony in any other place?
Mining? Bots can do that, slower but orders of magnitude cheaper.
Industry? Maybe. Most industry will be in Earth orbit though, simply beacuse it is vastly cheaper to ship ores than to bring workers far.
Scientific research? This is the only very good reason to stay far for a long time. If only Titan had something resembling alien life...

As I said, I don't know why we're in space in this scenario. Or how expensive things are. If space travel is relatively cheap we might do it for the living space - though I expect that would be a far-future scenario. If it's for mining the outer solar system we might find it advantageous to have humans near the mining machinery, Telepresence is limited by the speed of light and humans are still better at handling novel and unexpected situations than machines are, for example. That might mean orbitals near the gas giants where travel time between them and Earth is significant and those orbitals might be large with a lot of supplies/life support for small crews. We might have Mars orbitals as a base for mining the asteroid belt. We might have just Earth orbitals. Different scenarios yield different results.

That doesn't mean the victims of such an attack deserve to die, which is what you implied.

That statement holds true if you are acting alone, taking responsibility for your actions. If someone else is responsible for your safety, then matters get more complex, but the general idea is the same. If they as a whole don't take the fuss of having a decent security in critical areas (wich means asking just that to their politicians), then they shouldn't be amazed that a couple ill-equipped dissidents blew up everything.

You're essentially saying that if security isn't perfect people deserve to be maimed and killed, as it's their fault they haven't fixed the system. The problem with your attitude is that NO security system is perfect. The Bad Guys find and exploit faults.

Nobody "lets" known terrorists run around - the problem is that you won't know who they are until they do something - and if they are successful the first time then people suffer or die.

That's why an intelligence agency exists, they look if people start doing suspicious activities by infiltrating suspicious organizations and keeping good information networks. A lot of terrorist cells were stopped and arrested before they were able to do any real damage.

Being just reactive is ok for law enforcement, but not for an intelligence agency. They exist to be one step ahead of the threats and prevent them before they do any harm.
You can look at what CIA and FBI did in the past.

Yes. In addition to doing some good work they have also at times abused their power, harassed/persecuted the innocent and harmless, and let the Bad Guys run free. Again, no system is perfect.

An atmosphere thick enough to support human life will also tend to moderate temperature extremes,

I think this comes from the same misunderstanding as above. This is true, but only Earth has an atmosphere with those requirements.

Which is why terraforming is attractive, even if it may not be practical.

And in space you have micrometerorites, not so micrometerorites, radiation, and so forth.

Micrometeorites aren't a huge problem for a so big space station, bigger stuff can be detected easily and shot onto with lasers to deviate its course, asteroids can hit a planet much more easily than a space station.
Radiation is the same in orbit as on the surface of most other celestial bodies.
Well, maybe not on venus or gas giants, but those have worse problems.

The difference is that on a "celestial body" you have the option of burrowing underground. As it happens, the Earth's magnetic field provides some protection even in near Earth orbits. If a planet doesn't have a magnetic field it won't have that protection at all. So you have to build in the shielding, and that takes resources and space on the orbital that can't be occupied by something else.

And while meteors/asteroids can more easily hit a planet, being such a larger target, if they do hit a planet the damaged is limited whereas if they hit an orbital the destruction will be much more severe as it will damage a much greater portion of the habitat.

The big problem with terraforming, of course, will always be the cost in resources and energy. In most scenarios, terraforming, if possible at all, would take centuries as well. Most people aren't that patient.

[Sarevok]

Has anyone ever made a functioning system where plants provide oxygen ? All such attempts I know of, such as Biosphere 2 for example were dismal failures.

[Broomstick]

Has anyone ever made a functioning system where plants provide oxygen ? All such attempts I know of, such as Biosphere 2 for example were dismal failures.

If you actually research the Biosphere 2 experiment you'll realize that they never expected "success". The idea was to try to set up a biosphere and learn from what didn't work. To that extent, the failures were actually successes, in that there were things learned about what NOT to do next time.

Biosphere 2 had a problem with fluctuating oxygen and carbon dioxide levels. This was due in part to plants uptaking CO2 during the day, and switching from using CO2 to O2 at night when photosynthesis was not possible. This might be mitigated in a large habitat by having plant zones illuminated in shifts, so that, say, there are three 8 hour shifts, two lit and one dark, so that 2/3 of the plants are engaged in CO2"scrubbing" at any time. There was also a problem with the CO2 and O2 reacting with the concrete of the building to form calcium carbonate and reduce available carbon and oxygen for the ecosystem. In closed systems you have to be very careful about what materials you use, as material innocuous in an Earth environment can be a real problem in an enclosed environment

[someone_else]

Nonetheless, a few hours might be critical in an emergency.

They are less efficient than machinery. In the same space, machinery will keep people alive for at least double the time.
And frankly, pressurized oxygen tanks don't blow up so easily. It's the liquid gas tanks that go boom so often (due to misuse).

As I said, plants there will be, but won't be counted as a backup. Any help will be an added bonus to real backups.

Eating fresh food is unequivocally beneficial to humans for both physical and psychological reasons.

I said k-rations for emergencies. They will eat fresh food from hydroponics or whatever.

Tough shit - it's a plant. Hypocritical of you to advocate machinery then use algae.

Well, they are part of a pretty mechanized system that breaks down waste with non-biological machinery like supercritical water gimmicks into the nutients that will be then fed to them. They require much less space than more normal plants (the ones with roots and leaves).
My fault anyway.
Although... algaes could be eaten, and provide emergency food too.

Plants can survive for awhile if their "pod" malfunctions.

Uhm. Plants need sunlight.
So either the pod lets (filterd) sunlight come in from space, OR it uses lamps.
If power goes off, plants will either cook (cooling systems shut down) or sit in the dark.
Plants have around 17% conversion efficiency, so you have 80% of the sunlight heating up the plant bay.

Not really - the last few idiots in my area who climbed high voltage tower literally fried.

I said intelligent threat. And the fence didn't stop even those poor idiots.
Demolition experts can take down metal stuff with magnesium or thermite-like charges that melt iron. Since a malicious threat doesn't need to make the tower fall down without damaging things around it, it can just place the chagres in the areas close to the ground.

Which is one of my points, that you'll have multiple back up systems.

I think I was saying the same . The point that you seem to miss is that plants are a poor backup.
Ah yes, and obviusly backups won't be in the same area.

But you seem to advocate them over a terraformed planet.

Well well, with the same expense I can make millions of space habitats, and each one is an enclosed space with backups.
Unless I take pains to scatter them, they will be pretty close (astronomically speaking, they will be at hundreds or even thousands km of distance) to allow them to help each other easily.

No catastrophe nor realistic terrorist organization can affect them all. Without talking about novas or gamma ray bursts that would ass-fuck a planet too.
Synthetised:
One station < one terraformed planet
bunch of stations costed as terraforming = one terraformed planet (roughly)

Stations are somewhat more flexible than a planet (can be relocated, albeit slowly) and relatively safer from the odd "relativistic shell from hell" in case you have hostile aliens with magitech, and you can keep building them as long as you have materials.

They also rise with the rise of your space population, as Uncluttered said about domes (that are more or less the same). Terraforming does not, and requires to pay the whole cost in advance.

But sufficient escape pods for a population in the thousands will take up enormous space, even if resources are plentiful.

Well, an escape pod is little more than a coffin with rudimentary life-support. Let's say 4 m3 per person, that's 4000 m3 for a colony of 1000 people. A box of 20x20x10 meters for a station a few km wide. (in reality they will be scattered, but this is just a size comparison)

If space travel is relatively cheap we might do it for the living space - though I expect that would be a far-future scenario.

I'd like to make a point on this. Orbital travel and interplanetary travel are two very different beasts. A very rough analogy is between navigation in Mediterranean sea and Atlantic ocean. You can go from one side to the other of the Mediterranean with an oversized rubber dinghy in a couple days, but to get in America you need a decent ship and more time.
Orbital space travel is already relatively close to get cheap (does just require the will to go and stay there, and currently we lack the will... also called $), interplanetary travel (for human payloads) even to Mars requires orders of magnitude better engines to get anyhwere near making a profit. Jupiter and beyond require true magitech drives (still if you plan to make a profit).

If it's for mining the outer solar system we might find it advantageous to have humans near the mining machinery,

That would call for oil-rig like stations imho, where a few very well-payed emplyees stay for lots of time before going back home. Wich isn't a colony at all.
The point is that unless you send people in spacesuits to mine, you won't have more than a few dozen technicians per mine, and that doesn't make a mining city as we know it.

Most people will want to stay close to where all the action is (the reason why people prefer to live in cities here on Earth), and for a very long time that place will be Earth.
You will still have some loners like idealists that try to create utopias and religious fanatics that will want to stay far from civilization, but they aren't the bulk of population.

You're essentially saying that if security isn't perfect people deserve to be maimed and killed, as it's their fault they haven't fixed the system.

That wasn't a moral judgement.
That's cause-effect relationship. That's how everything works in this universe.
If you don't defend people properly from a threat, people dies from it.
I'would have made better rules, but that's what we have.

Yes. In addition to doing some good work they have also at times abused their power, harassed/persecuted the innocent and harmless, and let the Bad Guys run free. Again, no system is perfect.

I'd say those agencies did some slips, but are not that ineffective as you may think they are.
The total killcount of terrorist attacks is well below the amount of people that dies each year due to driving drunk or driving with cellphone (those last ones have also a dedicated place in HELL).
Or drug/alchool/smoke related illnesses.
The amount of critical equipment destroyed is much lower than the average natural disaster.
Mostly because they want to terrorize, not kill. And for that you need to make a spectacular show, not to be particularly efficient.

So you have to build in the shielding, and that takes resources and space on the orbital that can't be occupied by something else.

Sure, but I saw enough papers about creating magnetic fields around a spacecraft to protect from all space radiation. They were too heavy for a spacecraft, but a station will probably be able to afford them.
And even then, people survive in places on earth that are more irradiated than space in normal space weather (no solar flares/CMEs in your direction), so I keep hoping it won't be necessary.
A few storm shelters for the odd CME coming in your direction will hopefully be enough.
But that's my dream anyway, NASA people said that they really don't know the effect of long-duration permanence in space radiation environment. So I keep hoping.

And while meteors/asteroids can more easily hit a planet, being such a larger target, if they do hit a planet the damaged is limited whereas if they hit an orbital the destruction will be much more severe as it will damage a much greater portion of the habitat.

Sure, but since a station is at least ten orders of magnitude smaller, the odds of that happening are ten orders of magnitude lower as well.
We are getting again in the "it's more likely an heart attack" scenario.
Still, anything with a dangerous size can be seen and tracked and logged easily with modern tech.
Also because planets will already have very good reasons to place asteroid-surveillance systems.

Has anyone ever made a functioning system where plants provide oxygen ?

If for that you mean algae tanks, then yes. And supercritical water oxidators are a well-understood technology. I think noone tired to make a true life support out of them, though.
It is not easy anyway, but with algae you can adjust it more easily than with hydroponics.
(they grow fast)

[Zaune]

Something occurs to me about habitats. A few months back I read a quite memorably unenjoyable science fiction book that had Yggdrasil in the title and whose author's name escapes me entirely. One of its central concepts that I did find interesting was the idea that orbital habitats need not be big and centralised.
A number of individual habitats with independent air recycling systems, solar panels and septic tanks would lose some of the economies of scale, but gain greatly reduced prospects for collateral damage in the event of accident or sabotage. They could be linked up by structural supports, have cables and semi-permanent connecting tubes strung between them or even just be placed in very close orbits together and transitions between them made in an EVA suit. The habitats themselves could be as large or as small as their function dictated; there's no reason, besides possible financial ones, why single families couldn't purchase independent habitats the size of a typical family home on the surface.

It sounds more than a little harebrained even to me, but it does solve a lot of the logistical and societal issues thrown up by permanent habitats in space that amount to an entire town housed in a single building.

[someone_else]

One of its central concepts that I did find interesting was the idea that orbital habitats need not be big and centralised.

Centralization is a big no-no. One single critical system is just asking to be your doom.

The size has a structural lower limit, since if you want it to have gravity, you want to spin it, and if its structural mass isn't enough to ignore the movement of masses into it (namely, the inhabitants walking around), you get an unstable structure or you need a painfully complex load-balancing system.

That means at least something like 100 or 200 people per habitat is around the smallest you can get imho. I like to keep that number up to a thousand or so souls, just to be sure. That's a tiny town, mind me, roughly as popolous as 100 m2 of New York city.

A number of individual habitats with independent air recycling systems, solar panels and septic tanks would lose some of the economies of scale, but gain greatly reduced prospects for collateral damage in the event of accident or sabotage.

Ok for more than one hab, but all the other habitats must be able to keep more people than the stated max capacity (i.e. have significant backups) anyway, otherwise in case of failure of one hab, the refugees will overload the life support systems of others.
If each hab have some redundancy, you can activate backups at any time, and get more capacity to accept refugees from failed habs.
Since I was talking about double or triple redundancy, a hab of mine can keep two or three times as much people in an emergency. Not as confortable, but all safe and alive.

there's no reason, besides possible financial ones, why single families couldn't purchase independent habitats the size of a typical family home on the surface.

Huh, that's hardcore liberitarian madness if you ask me.
It's not impossible, sure but the costs (money and time) are kinda stupidly high.
It's like if any house here on earth has its own power plant (you can have RTGs for example), its own sewer treatment system, its own trash disposal system, its own fields and food-treatment machinery. Then you have the people living there occupied full-time keeping their own household and fields and machinery from falling apart.
Sure, that's as dispersed as you can get, but not what I'd call a good life for the inhabitants.
Either you specialize and team up with a few people to get some decent economies of scale or you live your whole life tending the stuff keeping your sorry alone arse alive.

Such hard-core individualism is plan stupid here on Earth, much before factoring space settlement in the equation.

[Zaune]

Oddly enough, hardcore individualism was a major theme of the story that set me to thinking about this. (Such things were made possible in this particular story by some sort of anti-gravity drive that you could buy in a kit and retrofit to any small jet aircraft, meaning that most such habitats were home-built by space geeks, loony survivalists and eccentric millionaires. Did I mention it wasn't very good?)
However, I wasn't suggesting that the individual units be completely self-sufficient; they'd need to resupply with food, drain the septic tank and so forth, meaning a certain amount of commuting to and from larger habitats to work and buy groceries, and support from contractors on one of the larger habitats. Think of a hard-SF take on those weird commercials British Gas is running with the slogan "look after your world".
Costwise, surface-to-orbit travel would have to be pretty cheap to make permanent dwellings in NEO a possibility anyway, and mass-production of these things would cut the per-unit price as well.

[someone_else]

Well, if you wanna make it half-realistic you can have each individual "house" unit that has no life support and relies on oxygen tanks and reusable CO2 scrubbers, (power comes from panels or an RPG).

Handwaving the instability problem of rotating a small station someway or staying in freefall your whole life.

Then you have bigger stations with plants or alagae or whatever that sell oxygen tanks and some guy that services the CO2 scrubbers. Every week or so comes the space flusher that takes the biological waste and brings it to the plant/alagae station.

But frankly I don't see the need for all this commuting.
May make you feel more free, but you are still pretty relying to those guys with plants/algae and the ones that sell you the food.

Think of a hard-SF take on those weird commercials British Gas is running with the slogan "look after your world".

That's a "US suburbs IN SPAACE!!!" scenario.

Uh, btw, I'm STRONGLY against a such scenario.
That's the same as those visions with "everyone with flying cars".
You seen how bad some can drive? Imagine that IN SPAAACE!!!

[Paula42]

large colony structures and altering the atmosphere over time enough that the colonies can filter it into being breathable is likely the only viable option for the terraforming and colonisation of mars.

[CaptainChewbacca]

large colony structures and altering the atmosphere over time enough that the colonies can filter it into being breathable is likely the only viable option for the terraforming and colonisation of mars.

Or you could do small remote outposts and lots of automated atmosphere processing. I know you're new and this is a necro, but Mars' atmosphere doesn't need 'filtered' in the way you are thinking. The atmosphere on Mars is so thin that even if it was balanced to earth ratios you couldn't survive on it. That's also part of why the planet is so cold; there isn't enough air to hold the heat.