Shirtsleeves on Mars?

[Spacethingy]

Now, please excuse me if this is silly, but...

Summer temperatures on Mars can get up to a reasonably warm/hot 20'C.

On some of these max temperature days, could an astronaut actually survive outside a base with no protection other than an O2 tank and some warm clothing? Or would the very thin atmosphere make temperature irrelevant?

It'd make doing jobs/walking around a lot easier without all that spacesuit clobber. :lol:

 

[TMac3000]

The air is thin enough that I'm pretty sure your blood would boil.

 

[Artlav]

Weren't there skintight space suits being developed (and imagined) since forever?
However, i don't think you'd get enough oxygen without sufficient pressure anyway - it's 3 psi or so for pure oxygen, and that's still way more than Mars have.

 

[C3PO]

The air is thin enough that I'm pretty sure your blood would boil.

Roughly 1/200 of Earth's pressure. Average 0.6 kilopascals (0.087 psi).

 

[RacerX]

Atmospheric pressure is less on Mars then on Earth. If you stepped outside into the low pressure of Mars everything liquid in your body would expand outwards. You basically swell up every pore and orifice on your body leaks blood and other fluids and you more or less explode!

 

[TMac3000]

Not to hijack, but just a quick question: what about shirtsleeves on Titan? Obviously a bad idea at -200 C, but the atmosphere would be more than thick enough. Seems everywhere you go other than Earth, there's always some reason for a space suit...

 

[N_Molson]

The air is thin enough that I'm pretty sure your blood would boil.

No. This is one of the most widespread misconception about the human body & space. The blood circulatory system is sealed, as long you aren't hurt.

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.

The human skin is elastic enough to hold everything in place. Martian gravity is going to help anyway. Eye/mouth/nose protection would be needed, as body fluids would evaporate in such a pressureless environnement. I guess it would be good to protect the ears too. So some kind of big gas mask that cover the ears too should be enough.

Note that during a suit test in a vacuum chamber in 1965', the suit integrity failed and the subject got exposed to near-vacuum. He suffered no permanent injuries.

Now of course, you don't want to get exposed to those conditions for hours, but in pressure contingency cases, you could probably walk to the next habitation module airlock.

---------- Post added at 07:21 PM ---------- Previous post was at 07:06 PM ----------

Obviously a bad idea at -200 C, but the atmosphere would be more than thick enough.

With 1,47 bars, 95% N2 and 4% methane, Titan atmosphere would probably be ok. However, I've no idea how the skin would react to a concentration of 4% of methane in the air. Again, I would protect the eyes and the ears (those don't like pressure variations, as you can feel when you take a plane).

Now the -200°C is of course an issue. You wouldn't immediately turn into a statue of ice (Hollywood movies like that !), but you would certainly be exhausted very quickly as your energy would be drained by the cold. Then the body protects the heart and the brain by closing blood vessels that aren't required for survival : you lose sensitivity in extremities first, then they ice, and you lose consciousness and eventually die when the brain temperature falls under an acceptable level (around 32°C I think).

However, an heating device should be enough like a light suit with electrical resistances in it. You would probably need to carry some fusion cell on your back to power the thing for a long time, though

 

[C3PO]

Note that during a suit test in a vacuum chamber in 1965', the suit integrity failed and the subject got exposed to near-vacuum. He suffered no permanent injuries.

http://www.orbiter-forum.com/showthread.php?p=368174&postcount=9

 

[N_Molson]

You can read more information about the incident here :

www.jsc.nasa.gov/history/roundups/issues/67-01-06.pdf

Look page 3. The rescuers were decorated and the technician wasn't seriously injured.

 

[T.Neo]

Fun fact: only relatively minor environmental alteration would be required on Mars to allow humans to survive outside unaided, provided they had access to breathing equipment, and proper clothing (depending on the weather).

 

[N_Molson]

and proper clothing (depending on the weather).

Don't forget the radiations, Mars magnetosphere isn't as powerful as on Earth, and there is no ozone layer. So long shirt, gloves, long pants, headgear anyway. Or maybe a super-duper sunscreen lotion. Well, that's for the UVs

For the gamma rays and those kind of nasty stuff... I fear that a spacesuit or a radiation suit are required.

 

[Artlav]

Now the -200°C is of course an issue.

That sounds somewhat cool. I'd expect the amount of clothes required would be somewhat more than a spacesuit.
Also, with that pressure the heat exchange would be severe, so any exposed skin would freeze quickly - no rebreathers, full unbroken suit needed.

Freezing of oxygen and co2 might be a problem if the breathing system is open-cycled.

All in all, it's worse than Rura Penthe.

 

[T.Neo]

Don't forget the radiations, Mars magnetosphere isn't as powerful as on Earth, and there is no ozone layer. So long shirt, gloves, long pants, headgear anyway. Or maybe a super-duper sunscreen lotion. Well, that's for the UVs



For the gamma rays and those kind of nasty stuff... I fear that a spacesuit or a radiation suit are required.

First consider UV and ionising radiation flux on Mars before worrying about such matters. Despite the lack of an ozone layer, insolation at Mars is roughly 40% that at Earth's orbit(1)- somewhat lessening, but not removing, the danger of UV rays.

Spacesuits provide limited protection against radiation regardless (charged particle radiation and cosmic ray nuclei are the major concerns,(2) with gamma and X-ray radiation generally not being a concern), and it should be noted that a thicker atmosphere would afford greater protection from particle radiation to people on the surface of the planet. Due to the lower gravity of Mars, more mass of gas per square meter is required for a given pressure.(3) In the case of a 150 millibar atmosphere, this would be around 4000 kilograms of mass per square meter (Earth is around 10300 kilograms of air mass per square meter and also possesses a magnetic field, though the strength of the magnetic field is thought to have been considerably reduced at certain points in history,(4) and the Apollo missions demonstrate that short-term excursions beyond Earth's atmosphere and magnetosphere are not problematic). In any case, the amount of shielding afforded to a person on the surface by such an atmosphere would be far higher than with the current atmosphere of Mars.

In any case, depending on temperature and the weather, it could be more important to shield the body from cold conditions than from UV rays. It must also be considered that clothing needed to protect against sunlight is far less restrictive, expensive, and critical than a pressure suit (the same goes for cold weather clothing, which is used by millions of people on Earth effectively and safely).

1. Can be calculated using the solar constant, the distance of Mars and Earth from the Sun and the inverse square law.
2. Space Radiation Environment
3. Can be calculated using gravity (0.38G or 3.726m/^2 on Mars) and the equation m=F/a.
4. [ame="http://en.wikipedia.org/wiki/Geomagnetic_reversal"]Geomagnetic reversal[/ame]

 

[Zatnikitelman]

Also based on what I can find, if you were breathing in pure oxygen, you'd still need a pressure roughly 26.6 times greater than Mars's atmosphere. From what I can find, the minimum safe partial pressure of O2 is about 16 kilopascals and I'm not sure you could survive that lung pressure differential for long periods without some kind of damage.

 

[Mattyv]

Isn't Mars-dust toxic? If it is, I think you would want to have some decent protection from that too.

 

[T.Neo]

Isn't Mars-dust toxic? If it is, I think you would want to have some decent protection from that too.

The protection you'd need would probably depend on what level of contact you would be expected to experience (it is doubtful, since a thick CO2 atmosphere would still be unbreathable and respiration systems would be used, that breathing in Martian dust would be a concern) and what effects the altered climate would have on the planet's surface chemistry.

 

[Andy44]

No suit to walk on Mars? Sure. You first.

 

[Codz]

No suit to walk on Mars? Sure. You first.

Where's your sense of adventure?:lol:

 

[C3PO]

Where's your sense of adventure?:lol:

Well, IMHO an advenure should last more then 5 seconds.

 

[jangofett287]

Well, IMHO an advenure should last more then 5 seconds.

This adventure would last more than 5 seconds. Stepping out of the ISS without a suit lasts 90 seconds. (not that you could step out of the ISS as all the hatches open inwards...)