Shirt sleeves on Duna?? Pack your coat and O2 tank!!!!

[autumnalequinox]

With Duna technically having a surface pressure of 0.2 atm and average temp around -40 C, a pressure suit would be unnecessary would it not? You could technically get away with being equipped like a climber going up Mt. Everest; with just heavy clothing and a breath mask with O2. Am I right or wrong?

I daydream sometimes about how amazing it would be if this were the case on Mars. Or if Venus was instead just a hot wind blown desert world with soda seas (instead of being equivalent to diving into 100s of meters of molten lead). Could you imagine how different our space program would be if there was even a slightly habitable world nearby??

No wonder the Kerbals are so obsessed with space flight. They have two marginally habitable worlds and one distant terrestrial world.. all in their HOME SYSTEM!

What an amazing gift that would be.

[dryer_lint]

Interesting... still, doesn't 0.2 atm seem awfully thin?

[autumnalequinox]

Oh definitely that's why you would need an O2 pack at the very least. How high do you need to go on Earth to reach 0.2 atm? Is that thin enough to boil your blood? Off to wikipedia....

[UmbralRaptor]

No wonder the Kerbals are so obsessed with space flight. They have two marginally habitable worlds and one distant terrestrial world

Yep!

It's important that people realize that Duna and Eva are not like our Mars and Venus, but closer to what we thought/hoped they were circa 1900-1950.

edit:

Oh definitely that's why you would need an O2 pack at the very least. How high do you need to go on Earth to reach 0.2 atm? Is that thin enough to boil your blood? Off to wikipedia....

Uh, something like 14 km to hit 0.2 atm. And your resting blood pressure is enough to keep it from boiling. Edited August 23, 2014 by UmbralRaptor

[autumnalequinox]

it may be. quick calculations suggest Earth has 0.2 atm of pressure at about 40k feet. http://www.regentsprep.org/Regents/math/algtrig/ATP8b/exponentialResource.htm

Mt Everest is 29k feet high. (google)

Anyone out there with some knowledge about when a pressure suit is needed? Would 40k require one? Or could you get away with maybe just a helmet?

- - - Updated - - -

Yep!

It's important that people realize that Duna and Eva are not like our Mars and Venus, but closer to what we thought/hoped they were circa 1900-1950.

edit:

Uh, something like 14 km to hit 0.2 atm. And your resting blood pressure is enough to keep it from boiling.

ooo you're right i messed up my calc.

[I_Killed_Jeb]

Yep!

It's important that people realize that Duna and Eva are not like our Mars and Venus, but closer to what we thought/hoped they were circa 1900-1950.

edit:

Uh, something like 14 km to hit 0.2 atm. And your resting blood pressure is enough to keep it from boiling.

i don't think your blood pressure has anything to do with it

[autumnalequinox]

I used to have a "This is Our Solar System" book from 1932. It had beautiful illustrations of the "surface" of Mercury, Venus, and Mars. At the time, they believed Venus to be a windswept desert with moderately high pressure, semi-tolerable temperatures (around 200 F) and soda seas. Mars had greenery in the summer. Mercury had cracks of molten rock. It set my imagination wild when I was young.

Edit: I'm not that old at all. It was my grandparent's book.

[SunChaser]

Pressure near the top of Mount Everest is 0.3 atm or less, which is enough to knock out somebody who hasn't acclimatized for an extended period of time, but pressure is not a concern if you have supplemental O2. If I'm not mistaken though, the pressure on Mars is 0.01 atm or less...definitely space-suit conditions.

Then there's the issue of dust, which obviously is not currently an issue on Duna in KSP but would be on Mars. Other than that, I think it would be doable, the big problem is if something went wrong on Duna, you're boned, while a climber who gets frostbite can be returned to base camp and may only lead to amputation.

[autumnalequinox]

Pressure near the top of Mount Everest is 0.3 atm or less, which is enough to knock out somebody who hasn't acclimatized for an extended period of time, but pressure is not a concern if you have supplemental O2. If I'm not mistaken though, the pressure on Mars is 0.01 atm or less...definitely space-suit conditions.

Then there's the issue of dust, which obviously is not currently an issue on Duna in KSP but would be on Mars. Other than that, I think it would be doable, the big problem is if something went wrong on Duna, you're boned, while a climber who gets frostbite can be returned to base camp and may only lead to amputation.

True. It would definately help save on weight and resources on any kind of manned mission, however. (Heating, scrubbing, weight of EVA suits). Plus it seems much easier to terraform an environment like that. Technically.. technically.. could water exist on the surface with that kind of pressure???

[UmbralRaptor]

i don't think your blood pressure has anything to do with it

It has everything to do with keeping your blood from boiling, though decompression sickness is still an issue. Your circulatory system pressurizes your blood to a bit above the ambient environment simply by pumping it through your body. (moreso with fighting gravity). It's pretty iffy at vacuum levels, but there are additional problems there...

Anyone out there with some knowledge about when a pressure suit is needed? Would 40k require one? Or could you get away with maybe just a helmet?

https://en.wikipedia.org/wiki/Armstrong_limit

[r_rolo1]

Technically.. technically.. could water exist on the surface with that kind of pressure???

Pressure, yes, temperature, not so much, unless you have a high salinity water...

[autumnalequinox]

so that explains the extra-large ice caps on Duna then....

So terraforming Duna might be as simple as raising the local temperature about 30 degrees C. Miles easier then Mars. And with the Armstrong limit far below Duna's atmosphere, you could get away with just acclimatization and an oxygen mask.

Edit: Really, it would take very little to make the place halfway habitable. You would have a CO2 atmosphere but a little heat and at least you would have cold oceans and a viable environment for plant growth. Hell as it stands right now some hardy plants might be able to survive there.

Edit 2: In caves, at least. Forgot about radiation.

Edited August 23, 2014 by autumnalequinox

[problemecium]

A human can actually survive in a complete vacuum if provided oxygen and some degree of thermal insulation. For a while at least. And of course it would be extremely painful.

[I_Killed_Jeb]

It has everything to do with keeping your blood from boiling, though decompression sickness is still an issue. Your circulatory system pressurizes your blood to a bit above the ambient environment simply by pumping it through your body. (moreso with fighting gravity). It's pretty iffy at vacuum levels, but there are additional problems there...

https://en.wikipedia.org/wiki/Armstrong_limit

Again, I'm not sure why the hydrostatic pressure exerted by the blood on your blood vessel (aka Blood Pressure) has anything to do with the partial tension/pressure of dissolved gasses in your blood, which is the actual issue at hand. You can boil blood at normal atmospheric pressure (i.e. The Bends) so again I don't know what blood pressure has to do with it.

[LABHOUSE]

.33 is enough to survive but if you expanded it would be less I imagine.

But if you were slowly accustomed to it you may be alright.

Edited August 24, 2014 by LABHOUSE

[cantab]

Even though I understand it scientifically, cold boiling (by putting a container of water in a vacuum chamber and pumping the air out) is still just plain surreal. /tangent

[UmbralRaptor]

Hm. Looks like some US suits went down to 0.3 atm. Various Sokol derivatives were supposed to be at 0.4 atm, but could operate at 0.27 atm in an emergency.

Again, I'm not sure why the hydrostatic pressure exerted by the blood on your blood vessel (aka Blood Pressure) has anything to do with the partial tension/pressure of dissolved gasses in your blood, which is the actual issue at hand.

It's still a pressurized environment, so it should up the boiling point and solubility a bit. Not enough pressure to avoid gasses (ie: nitrogen) coming out of solution in the short term in either the 0 atm or 0.2 atm case, but for 0 atm, it would at least keep blood from vaporizing and leaking out. Of course, the lack of oxygen and possibly getting an aneurism from the gas coming out of solution (like you said) is rather unhealthy.

You can boil blood at normal atmospheric pressure (i.e. The Bends) so again I don't know what blood pressure has to do with it.

I'm not sure I would call dissolved gasses coming out of solution boiling.

[NERVAfan]

There's some sort of issue with a minimum pressure in the alveoli to breathe effectively, which is why spacesuits that use pure oxygen are pressurized to much higher partial pressures of oxygen than actually exists at sea level (much more than 3 psi). I don't understand it completely, but you can't just use an oxygen mask at really low external pressures.

http://en.wikipedia.org/wiki/Space_suit#Operating_pressure

[Renegrade]

-40c is apparently survivable. Here in T.O. it can get below -20c, which is nastily, violently cold, but survivable. 'Winterpeg' in Manitoba can reach -45c, and Regina in Saskatchewan can reach -50c, and people allegedly live there and don't die every time there's a cold snap, so those temperatures must be (barely) survivable too. Well, allegedly survivable.

I'd pack some extra long johns though.

I'm not sure I would call dissolved gasses coming out of solution boiling.

You might be able to say the gas itself is boiling(maybe), but I agree -- the solution it's coming out of is absolutely 100% not boiling. Like when CO2 fizzes out of coke - the coke itself is not boiling. Just (maybe) the CO2 itself.

I wonder if a vampire would consider the blood of someone with the bends to be 'effervescent' ...

Anyhow it sounds like the pressure would have to be raised to 34kPa-ish. That's a lot easier for Duna (both smaller volume to fill and already at a higher pressure) than Mars.

Some people seem to think Laythe is a good place to colonize (it's roughly Kerbin/Earthish, some oxygen, etc), but I think they forget that it should have about 4% of the solar power of Kerbin. Plants would require large solar concentrators or artificial lighting.

Duna should be about 39% of Kerbin's solar level, which would make solar power and plant growth a great deal easier.

Leaving aside the silly OP nature of solar panels in the outer system.

[brianorca]

It has everything to do with keeping your blood from boiling, though decompression sickness is still an issue. Your circulatory system pressurizes your blood to a bit above the ambient environment simply by pumping it through your body. (moreso with fighting gravity). It's pretty iffy at vacuum levels, but there are additional problems there...

https://en.wikipedia.org/wiki/Armstrong_limit

Your blood pressure only helps with your arteries. Veins will still be low pressure, and I've read an article that stated that the heart operates at least partly as a "vacuum pump" to pull blood up from the legs. This would imply that before it enters the right atrium, the blood would actually be below the ambient pressure.

But your link to the Armstrong limit is useful, which is 0.06 atmosphere. So we could get away with 0.2 on pure O2.

[Cirocco]

A human can actually survive in a complete vacuum if provided oxygen and some degree of thermal insulation. For a while at least. And of course it would be extremely painful.

1 to 2 minutes in space without a space suit was the estimation last time I did some research on it (about a month or two ago). It depends on whether you're simply talking "vacuum" or "in space within relative proximity to a star". The vacuum is the biggest problem of course, but in space you also have to deal with the radiation and high-energy particles as well, which would give you all sorts of nasty long-term effects even if you're miraculously saved within those 1-2 minutes.

The "if supplid oxygen" is also a bit of a problem because if you're breathing in air at anything even remotely close to atmospheric pressure, your lungs would rupture because of the pressure differences between the air in your lungs and the vacuum. If the oxygen were to be supplied in another way or perhaps if you're breathing a high-oxygen mis at very low pressures it might work? Though breathing different mixes of gasses at different pressures tends to bring along a whole slew of its own problems.

But yeah, effects of being exposed to vacuum include: you body swelling up as your bodily fluids are below their boiling pressure (you wouldn't burst though, apparently your skin is too tough for that. You'd just be in extreme pain as parameciumkid mentioned). Provided you didn't try to hold your breath (in which case your lungs would rupture and you'd be looking at certain death) you'd lose conciousness after about 10-15 seconds, water in your body would rapidly start evaporating out of your mouth and eyes and possibly other orifices. If you're in space you can add the solar radiation to that, giving you a massive sunburn and DNA damage, though honestly that's the least of your problems at that point.

Surprisingly, the cold isn't much of a problem. While it can be very, very cold in space, a near perfect vacuum provides an excellent insulator and the vacuum would kill you loooooong before the cold ever did.

So yeah, keep your spacesuit on kids

[sedativechunk]

Interesting discussion. I don't know the science behind it, but some people here are talking about Mount Everest. Not-to-long ago I went on a big Everest blitz watching all kinds of footage and even thought about going there someday when I'm older to summit the mountain (fyi, it gave me terrifying nightmares actually thinking about it for weeks).

Everest peaks at 29,029 feet, and is commonly romanticized as the tallest mountain in the world (mount Chimborazo in Ecuador is actually the highest point on planet Earth). Anyway has anyone actually researched and watch footage of people climbing Everest? It's pretty terrifying. Even at the lower altitudes of 20,000~ feet, people start suffering from decompression sickness, especially those who aren't used to it. Shortness of breath, vertigo, skin anomalies, and fatigue are just a few of the issues the climbers have, not to mention they can suffer blindness from the sun/snow, sunburns, and more.

I suppose Duna might be doable, and I'm sure if such an opportunity existed, someone would try it without a suit in reality because that's how humans are. But on the real life Mar's it's not happening. With that being said, the upper atmosphere of Venus is similar to Earth, and assuming you could make something like "Cloud City" then you might be able to survive in a place like that without a suit...

[worir4]

Don't forget the high radiation levels on Duna. This could also be a problem unless Kerbals are related to cockroaches.

[benzman]

To keep with the OP's question, and if I remember some of the details of the one-day Aviation Medicine lecture that I attended some thirty years ago, Earth's atmosphere contains 21% oxygen and the rest inert gasses. This means that if you climbed to an altitude corresponding to 21% sea level pressure, about 38,000 feet, breathing pure oxygen would give you the same mass (not volume) of oxygen as if you were breathing normal air at sea level. Above that the reduced oxygen pressure would require you to have a restraining garment to stop your chest expanding and the oxygen would need to be blown into you under some pressure from a tightly sealed face mask. Pressure breathing requires quite a bit of practice in a high altitude chamber as it is an abnormal way to breath. At about 60,000 feet you get into the blood-boiling area and need a full pressure suit. But yes, all other things being equal regarding temperature, radiation, etc. it should be possible to walk on Duna's surface with just an O2 tank. On the lower parts of the terrain anyhow.

[cantab]

Regarding plants on Laythe, wouldn't there be some that would still grow, just more slowly? At least in a warmed greenhouse.