[Phantom Hoover]

the most immediate uses will be in fertilizer and flameproofing of pressurized envrionments.

Is it actually needed for flameproofing? If you have a pure oxygen atmosphere at 0.2 bar it shouldn't cause any increase in flammability, since the partial pressures are the same.

[Dragon]

0.2 bar might not work for breathing. NASA pressurizes its space suits with pure oxygen at 32.4kPa (about 0.32 bar), and this is the absolute minimum (if it wasn't, they'd likely have gone lower). Also, it's not only about partial pressures. Oxygen+nitrogen mix is apparently less flammable than pure oxygen, even at reduced pressures. Martian habitat would likely have atmosphere composition similar to the ISS.

[headdie]

0.2 bar might not work for breathing. NASA pressurizes its space suits with pure oxygen at 32.4kPa (about 0.32 bar), and this is the absolute minimum (if it wasn't, they'd likely have gone lower). Also, it's not only about partial pressures. Oxygen+nitrogen mix is apparently less flammable than pure oxygen, even at reduced pressures. Martian habitat would likely have atmosphere composition similar to the ISS.

I presume this works because the human body only takes in a small amount of the available oxygen at sea level so with a monitored breathing environment you can reduce the atmo pressure thus reduce the mass needed for life support

[BirdofPrey]

As far as pressures go, earlier spacecraft used lower pressures with a higher oxygen percentage since it reduced the mass required to contain that atmosphere, if the hull is lighter, you can put more in it for a given rocket.  Spacesuits use the low pressure since it requires less effort to move (at sea level pressures, you wouldn't be able to move at all, but even with the reduced pressure, they are still hard to move).  The reason you can't go much lower has little to do with breathing and more to do with the fact, your body requires a certain amount of pressure pushing back against it.  To low and you risk discomfort and even injury.

[headdie]

that makes sence

[Phantom Hoover]

As far as pressures go, earlier spacecraft used lower pressures with a higher oxygen percentage since it reduced the mass required to contain that atmosphere, if the hull is lighter, you can put more in it for a given rocket.  Spacesuits use the low pressure since it requires less effort to move (at sea level pressures, you wouldn't be able to move at all, but even with the reduced pressure, they are still hard to move).  The reason you can't go much lower has little to do with breathing and more to do with the fact, your body requires a certain amount of pressure pushing back against it.  To low and you risk discomfort and even injury.

I'm sceptical. Most of the human body is incompressible, and the air spaces that aren't are very easily equalised. Technical divers can move from tens of atmospheres down to one over the course of several hours with minimal ill-effects (and most of the risks are from things like narcosis and decompression sickness which just don't exist in a low-pressure oxygen environment), I don't see why living at 0.2 atmospheres would be unsafe.

[Dragon]

Probably for the same reasons you can go into water with only an oxygen mask, but you can't do the same in space. Human body is incompressible, but it can (and will) swell up if the pressure outside is too low. Those are not the same thing, resistance to compression is different from resistance to expansion. You could likely get away with 0.2 atmospheres if you wore a biosuit to provide pressure (this is the kind of suit does allow you to go out into space with just an oxygen mask and earplugs, while being fairly unencumbering), but if you want a true shirtsleeve environment, you need at least 0.32 atm at least.

[BirdofPrey]

Space station crew actually have to spend a bit of time in the airlock before a spacewalk to remove some of the nitrogen from their bodies.  Even if that pressure is above the armstrong limit, the reduce pressure does lead to increased evaporation and outgassing, so it IS still possible to get the bends.

Probably for the same reasons you can go into water with only an oxygen mask, but you can't do the same in space. Human body is incompressible, but it can (and will) swell up if the pressure outside is too low. Those are not the same thing, resistance to compression is different from resistance to expansion. You could likely get away with 0.2 atmospheres if you wore a biosuit to provide pressure (this is the kind of suit does allow you to go out into space with just an oxygen mask and earplugs, while being fairly unencumbering), but if you want a true shirtsleeve environment, you need at least 0.32 atm at least.

Going out with just an air-mask and earplugs doesn't sound safe to me at all, what if the earplugs leak?  then you're looking at a ruptured eardrum, and where's the eye protection?  The mechanical counter-pressure suits they are working on right now tend to have a bubble helmet and pressurized boots and gloves (since it's proving difficult to provide sufficient counter-pressure to the digits; yes ladies and gentlemen, space gloves still suck)

[headdie]

in an environment like Mars I imagine that needing a heavy glove and boot setup would in some ways help with insulating and maintaining comfortable temperatures over the finger joints for manipulating objects and with the feet to thermally separate the wear's suit from the ground.  Also heavy/weighted boots may help with mobility by providing movement resistance which is more familiar and helping the person to stay upright in a stumbling/tripping situation as it would shift their center of balance downwards

[Dragon]

Space station crew actually have to spend a bit of time in the airlock before a spacewalk to remove some of the nitrogen from their bodies.  Even if that pressure is above the armstrong limit, the reduce pressure does lead to increased evaporation and outgassing, so it IS still possible to get the bends.

This is because they maintain a normal sea level atmospheric pressure inside the station. If you lowered the pressure (or lived in airlock-grade air), they wouldn't have to pre-breath.

Going out with just an air-mask and earplugs doesn't sound safe to me at all, what if the earplugs leak?  then you're looking at a ruptured eardrum, and where's the eye protection?  The mechanical counter-pressure suits they are working on right now tend to have a bubble helmet and pressurized boots and gloves (since it's proving difficult to provide sufficient counter-pressure to the digits; yes ladies and gentlemen, space gloves still suck)

Yes, you'd certainly want googles and very good earplugs, at the very least. You would survive, given that, even though it would likely not be comfortable. That you can doesn't mean you should. For a non-emergency EVA, a full helmet, gloves and boots would definitely be preferable.

[BirdofPrey]

If you have time to put on a space suit, you have time for the helmet too.  If not, you don't want to breathe anyways, since without counter-pressure on at least your chest, your lungs would over-expand and rupture if there were gas in them.  That said, you will be conscious for a minute in hard vacuum, so you could totally do the Dave Bowman thing and jump from ship to ship.

[Phantom Hoover]

Space station crew actually have to spend a bit of time in the airlock before a spacewalk to remove some of the nitrogen from their bodies.  Even if that pressure is above the armstrong limit, the reduce pressure does lead to increased evaporation and outgassing, so it IS still possible to get the bends.

Not if the environment is pure oxygen with no inert gas, and you exclusively use it at low pressures. As for your claims that it would be physiologically damaging, the Apollo astronauts spent extended times in suits at .26 bar, and lived for days in cabins pressurised to .33 bar.

[Dragon]

If you have time to put on a space suit, you have time for the helmet too.  If not, you don't want to breathe anyways, since without counter-pressure on at least your chest, your lungs would over-expand and rupture if there were gas in them.  That said, you will be conscious for a minute in hard vacuum, so you could totally do the Dave Bowman thing and jump from ship to ship.

The idea with biosuits is that you don't need to put them on. You wear those as underwear on a daily basis. They're light and unencumbering (though the latter part is not perfected yet), so assuming they can be made comfortable enough (another thing we're working on), they could be used that way. It'd be an excellent way of providing at least some protection to astronauts in case of an emergency.

[procdrone]

I don't know if that was mentioned here, but I was playing Doom 3 recently, and they had some nice scientific solutions.

For instance, use of Mars atmosphere, to seperate oxygen and hydrogen... and with these two, you have air, water, fuel... pretty much basics for survival on other planet. Of course that was done with some SCI-FI developed engineering... but it isn't as much out of reality (I think).

[Rheyah]

No one is going to Mars.  It's a waste of time compared to taking advantage of the Moon for orbital construction first and de-orbiting a lot of satellites in the process.

We need to clean up Earth's orbital zone before we go planting people on Mars.

[headdie]

No one is going to Mars.  It's a waste of time compared to taking advantage of the Moon for orbital construction first and de-orbiting a lot of satellites in the process.

We need to clean up Earth's orbital zone before we go planting people on Mars.

very strongly disagree

While it is not as immediate as some think, it will happen.  While the Moon is closer so easier to support from Earth it has a much smaller habitation and resource potential.  Mars also possesses an atmosphere which contains elements that can be harvested for life support and potentially transformed with outside input into one that is human viable.  The Moon is a good point for developing technologies and techniques that would be useful in the early days of Mars but ultimately the Moon be little more than an island like the UK compared to the continents like Eurasia of planets like Mars.

Yes the investment, Particularly in Time will be massive for Mars, the return for humanity is massively more than the Moon will ever offer.

[AtomicClucker]

No one is going to Mars.  It's a waste of time compared to taking advantage of the Moon for orbital construction first and de-orbiting a lot of satellites in the process.

We need to clean up Earth's orbital zone before we go planting people on Mars.

Better that our virtual tax dollars send canned primates to space then wasting then on local government stupid. Despite space programs being a "waste" how much more is wasted across the board by governments overall? Just ask the F-35 program XP. For all the "no bueno" stances, I've yet to see a coherent response to what we call corruption and waste. For all the hullabaloo about the expense of space travel, I think it's a better waste than letting governments bleeding money left and right for a chorus of reasons you can make an operatic epic out of it.

Less welfare, less defense spending, and more accidents and mishaps as we conquer Mars!

Though I'd say one element would be building the proper infrastructure to get to Mars. Imagine a part of the game is in Earth orbit building the infrastructure, space elevators, and other orbital facilities, and even using the Moon as a part of larger strategic jumping pad to mars. Half of the battle is just building the engine of colonization - imagine that orbital windows, Hoffman orbits, are yes, SPAAAAACE! are vital parts of shipping, resupplying, and send more monkeys its way.

[Mars]

We should colonize Mars after we've successfully colonized central Nevada.

[karajorma]

You only say that cause you don't want people sticking flags in you.

[666maslo666]

Before any colonization is attempted, we should build self-sufficient habitats here on Earth. By that I mean habitats that would recycle everything including air and only require energy to run for years, like Biosphere. Such technology would be very important for any deep space missions and could have many spin-offs here on Earth, too.

The next stage would be trying it out on the Moon.