What are effects of exsposure to Mars - Help with an answer

clark · 2003-07-15 07:34:33

Not sure where this should go, but I would like a 'scientific' answer, so maybe someone can help.

What would be the actual physical results of exsposure at Mars level pressure (and atmosphere) if somebody fell out of the airlock?

Would they kind of explode?

Palomar · 2003-07-15 08:04:22

*Gosh dang it, Clarkie! Didn't you ever see the movie "Total Recall"?! All that eyeball-swelling, scarlet-faced wheezing...

But seriously, wouldn't the carbon dioxide in the lungs begin to boil, then explode? I thought I read something like that...somewhere.

--Cindy

prometheusunbound · 2003-07-15 12:11:53

less pressure lowers the boiling point, so room temperature in a low-pressure enviroment is enough to boil your blood and bodily fluids. In space (no pressure whatsever!) blood boils off in 15 seconds (2001 was way off with that guy surriving exposure, he would have not had enough blood to maintain his surival. . .)

clark · 2003-07-15 12:16:56

It's pretty cold on Mars though, so would your blood still boil, even in the lower pressure?

I guess we can assume that the eyeballs explode into fine paste.

The capallieries though? Would the skin explode open?

Is there enough atmosphere on Mars for someone to hear a scream?

prometheusunbound · 2003-07-15 12:48:55

if there is matter, there is sound. so, yes, a scream on mars would be heard.

I don't know if blood would boil on mars, but I bet it does.
Trust me. :;):

Palomar · 2003-07-15 12:57:33

It's pretty cold on Mars though, so would your blood still boil, even in the lower pressure?
I guess we can assume that the eyeballs explode into fine paste.
The capallieries though? Would the skin explode open?
Is there enough atmosphere on Mars for someone to hear a scream?

*Clark, STOP IT! I just got done eating! :angry:

But seriously...what's up with the macabre stuff? Are you itching for Halloween or something?

--Cindy

clark · 2003-07-15 13:05:02

But seriously...what's up with the macabre stuff? Are you itching for Halloween or something?

No, but Halloween on Mars might have some different boogey monsters.

I am merely exploring some less discussed topics related to Mars. No one getting cold feet are they? :laugh:

Thanks for the info prometheusunbound, but I believe I have found a little more in depth information... finally.

go here:

http://www.sff.net/people/Geoffrey.Landis/vacuum.html

It details what exspsoure to space vacum would be like- and according to it, Clarke got it right (2001).

From the site:

Could You Survive?
The best data I have comes from the chapter on the effects of Barometric pressure in Bioastronautics Data Book, Second edition, NASA SP-3006. This chapter discusses animal studies of decompression to vacuum. It does not mention any human studies.

page 5, (following a general discussion of low pressures and ebullism), the author gives an account of what is to be the expected result of vacuum exposure:
"Some degree of consciousness will probably be retained for 9 to 11 seconds (see chapter 2 under Hypoxia). In rapid sequence thereafter, paralysis will be followed by generalized convulsions and paralysis once again. During this time, water vapor will form rapidly in the soft tissues and somewhat less rapidly in the venous blood. This evolution of water vapor will cause marked swelling of the body to perhaps twice its normal volume unless it is restrained by a pressure suit. (It has been demonstrated that a properly fitted elastic garment can entirely prevent ebullism at pressures as low as 15 mm Hg absolute [Webb, 1969, 1970].) Heart rate may rise initially, but will fall rapidly thereafter. Arterial blood pressure will also fall over a period of 30 to 60 seconds, while venous pressure rises due to distention of the venous system by gas and vapor. Venous pressure will meet or exceed arterial pressure within one minute. There will be virtually no effective circulation of blood. After an initial rush of gas from the lungs during decompression, gas and water vapor will continue to flow outward through the airways. This continual evaporation of water will cool the mouth and nose to near-freezing temperatures; the remainder of the body will also become cooled, but more slowly.

"Cook and Bancroft (1966) reported occasional deaths of animals due to fibrillation of the heart during the first minute of exposure to near vacuum conditions. Ordinarily, however, survival was the rule if recompression occurred within about 90 seconds. ... Once heart action ceased, death was inevitable, despite attempts at resuscitation....

[on recompression] "Breathing usually began spontaneously... Neurological problems, including blindness and other defects in vision, were common after exposures (see problems due to evolved gas), but usually disappeared fairly rapidly.

"It is very unlikely that a human suddenly exposed to a vacuum would have more than 5 to 10 seconds to help himself. If immediate help is at hand, although one's appearance and condition will be grave, it is reasonable to assume that recompression to a tolerable pressure (200 mm Hg, 3.8 psia) within 60 to 90 seconds could result in survival, and possibly in rather rapid recovery."

Note that this discussion covers the effect of vacuum exposure only. The decompression event itself can have disasterous effects if the person being decompressed makes the mistake of trying to hold his or her breath. This will result in rupturing of the lungs, with almost certainly fatal results. There is a good reason that it is called "explosive" decompression.

clark · 2003-07-15 13:33:41

Here is another website:

http://imagine.gsfc.nasa.gov/docs/ask_a … 70603.html

Real life experience:

At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.

Feeling the saliva boil off the tongue... wow!

Quite a host of new experiences awaiting future space colonists, no?

Josh Cryer · 2003-07-15 17:32:43

I guess the idea of airlock races are out of the question, eh? What would one require for minimal protection (say, being able to be exposed as long as you can hold your breath, approximately 3 minutes or thereabouts)?

I thought that basically, if your mouth, eyes, ears, etc were covered tightly, you'd be okay? Basically, what would the minimal clothing requirements be?

prometheusunbound · 2003-07-16 06:56:55

if you held your breath your lungs would explode like dynamite (well maybe like a m-80) and you would die almost instantly as your torso would be like an exploding balloon. (explosive decompression, baby)

Note that this discussion covers the effect of vacuum exposure only. The decompression event itself can have disasterous effects if the person being decompressed makes the mistake of trying to hold his or her breath. This will result in rupturing of the lungs, with almost certainly fatal results. There is a good reason that it is called "explosive" decompression.

clark · 2003-07-16 10:26:26

Actually, holding your breath is by far the worst thing you can do in such a situation. In fact, you stand a better chance of survival, with less physical damage, if you exhale as much as you can prior to decompression.

Otherwise, your lungs will explode out of your throat.

the literature that exsists suggests that 60-90 seconds of vacum is survivable, with minimal physical damage. Your eyes are the most likely to be destroyed in such an event. So coverings for the eyes are neccessity.

It appears that our skin would be able to maintain the pressure, so we wouldn't explode- but i would hate to imagine what the results of an open wound in such an environment would lead to.

The bare minimum of clothing would be at the very least some type of pressure suit, as the pressure level on Mars is so low as to cause swelling. The web site linked to recounts how a high altitude parachute jumper lost pressurization in his right glove, his hand swelled to twice the size, and became very painful. Same thing would happen to any part of your body left exsposed to Mars atmosphere.

Once again, man can go to the stars, but never touch them.

Bill White · 2003-07-16 10:56:31

I had already seen many of clark's links and I believe the 2001 movie is closer to the truth - even with some errors.

My understanding is that the head openings are crucial because fluid and gases can pass easily through or across the eyes, ears nose and mouth. I agree with clark, exhale fully to survive brief vacuum exposure.

Marsians could wear long underwear fashioned like a wetsuit - combination lycra, spandex and air impermeable materials to constrict the body and enhance skin integrity. Like support hose worn by the elderly, folks with weak circulation and pregnant women only it encloses the entire body. I might guess air permeable would be okay so long as the garment supports the skin and blood vessels. A permanent garment rarely removed.

Remember, skin is really tough stuff. Very effective at keeping stuff in, and out, of the body. Thats wby I prefer skin on salmon for BBQs - much harder to burn if I forget the grill.

NASA "Snoopy" caps could constrict in an emergency to seal off the ears (radio receiver inside) leaving the eyes, nose and mouth. Emergency goggles and a nose/mouth mask with a limited oxygen supply could be carried by all at all times.

I also believe that internal pressure in a habitat should be as low as can be safely sustained. Increase the O2 as needed to give the necessary oxygen partial pressures but cut back on N2 partial pressures or others to reduce overall preswsure as low as is feasible.

This reduces the potential for injury similiar to "the bends" or the tendency for blood gases to boil.

Someone once wrote that scuba divers who go deep face far greater dangers from pressure differentials than any astronaut ever would. Set Mars internal hab pressure at .5 Earth sea level normal and upon exposure to vacuum human blood gases will boil much more slowly than if the hab pressure was sea level normal.

Bill White · 2003-07-16 11:03:02

It appears that our skin would be able to maintain the pressure, so we wouldn't explode- but i would hate to imagine what the results of an open wound in such an environment would lead to.

Living with lower hab pressures would mitigate this danger, right?

There are other dangers from having permanently lower hab pressures but the stress on hab structure itself and the danger of blowouts - whether of the habitat or the body integrity of people would seem to be reduced.

clark · 2003-07-16 11:23:00

Living with lower hab pressures would mitigate this danger, right?

I'm not sure, but I don't think so. Even though people might adapt to the lower pressure, nothing is being chaged within the body really. The links talked about how blood pressure is really maintained in relation to the outside environment (if I am wrong, please correct me). So I don't see how living in a lower pressure changes anything permanently.

Of course lower difference between extreme changes of pressure is probably less of a shock to the system, so overall, it would bea good idea.

smaller pressure differentials will also allow for quicker entry and exit between the airlocks, I would imagine.

I think there is an added danger though of being exsposed to Martian vacum- the carbon dioxide might very well poision you immediatly.

So if your eyes don't blow out of your skull, you'll still probably be dead from the 'air'. Great! ???

Bill White · 2003-07-16 12:07:28

I post mostly as a layperson who uses google. . .

I am sure RobertDyck can correct us all on these points. But to continue anyways,

I believe blood pressure in the medical sense is not really the same as the pressure of gas found in the blood. I also believe each cell of our bodies has mechanisms to cope with pressure changes and going from .5 to 0 will be less of a shock that 1.0 to 0 even if internal cell presures (fluid or air) remain more or less constant.

When scuba divers go deep, increased N2 enters the blood the same way CO2 enters a can of Coke or seltzer water. The pressure inside a sealed soda can is higher than the outside air, forcing the gas to dissolve in the liquid. Open the can and gas bubbles out as the pressure equalizes. If the pressure in the soda bottle were 2 atmospheres rather than 1.25 atmospheres, opening the bottle would be more explosive.

If the pressure of the Mars hab were 0.5 rather than 1.0 sudden decompression would be less violent.

Not all gases can enter the blood, apparently. Deep divers use other mixes to avoid the bends and that may be another way to go.

Clearly, the only answer is research.

dickbill · 2003-07-16 13:56:45

If the pressure of the Mars hab were 0.5 rather than 1.0 sudden decompression would be less violent.

That's correct and recreational divers are teached a golden rule: never hold your breath when you ascent. That's the most important, otherwise the lung dilatation can cause injury and death.
Recreational dive are recreational because at the maximum depth allowed, 120 feet max (somtimes 140 feet, but the maximum adviced is actually 100 feet for recreational unexperimented diver), you can still breath compressed air, while deeper you would need mixtures and, most importantly, decompression steps to get rid of the dissolved gas in the tissues. When out of air at the bottom, so in case of very extreme emergency, a well trained recreational diver is supposed to ascent, while exhaling, the all 120 feet, which is 5 atmospheres of pressure (1 atm every 30 feet/10 meters + 1atm of air at sea level), and this without any decompression step, straight. But, you could ask, if you are out of air, how can you exhale ? that's precisely because even the few air left in the lungs expends during ascent and decompression, that little remaining can actually fill the lungs and, some people told me, you feel your lungs full of air again.
That's dangerous because you reach the surface with full nitrogen load in the tissue, but you can survive it. So I think you can survive 4 or maybe 5 atmospheres difference (at sea level) of decompression, while going from 1 or even 0.5, to 0 seems letal.
So I am not sure that a dive emergency ascent is more dangerous than an exposure to vacuum and I would still prefer a 120/140 feet emergency ascent than having my lungs exposed on MArs.

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#1 2003-07-15 07:34:33

Re: What are effects of exsposure to Mars - Help with an answer

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Re: What are effects of exsposure to Mars - Help with an answer

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