Author Topic: Is EVA without space suit possible?  (Read 27029 times)

Offline Nikola

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Re: Is EVA without space suit possible?
« Reply #20 on: 02/26/2011 12:45 am »
Physician here; have dealt with a few patients from scuba accidents (too rapid ascent).  Basically, Jim's estimate and background reasoning is closest to accurate with regard to what would happen with spacesuit failure/rapid depressurization.  Most critical issue has to due with the solubility of critical gases in the blood (i.e., nitrogen and oxygen).  The oxygen/hemoglobin dissociation curve is greatly shifted in situations where ambient pressure changes rapidly;partial pressures and solubility of these critical gases just "can't keep pace" with the rapid change in ambient pressure.  Blood doesn't actually "boil" per se, but rapid release of gases from the blood would have a similar effect.  Rapid development of pulmonary edema and possible gas bubble embolism would be the killing event, likely within 45 seconds to a couple (2) minutes, max...  Gruesome way to die but rapid loss of consciousness would ensue well before cardiopulmonary collapse.

Thank you vh5150 , I am very happy to get answers
from a Physician!

Actually, original idea was to slowly approach the conditions of vacuum, without rapid depressurization.

For example start at 10 kPa (1.5 psi) pure oxygen environment, and than reduce pressure slowly.  Of course, use pipe with pure oxygen supply. Pipe would have a tight seal on the mouth.



Offline Nikola

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Re: Is EVA without space suit possible?
« Reply #21 on: 02/26/2011 12:54 am »
I've summarized in one graph the conditions in the lungs, and known (to me) effects on humans.

For me, it looks like there is a chance that lungs will not fail in a matter of minutes and they have perhaps more time.

This of course does not exclude rapid heart failure.
« Last Edit: 02/26/2011 01:02 am by Nikola »

Offline A_M_Swallow

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Re: Is EVA without space suit possible?
« Reply #22 on: 02/26/2011 01:12 am »
It looks like the spacesuit could do with some one way valves to stop the air escaping.  Possibly based on artificial heart valves.  On the air intake pipe and around the neck.  Something activated by pressure difference may work in the outtake tube.

Offline Jim

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Re: Is EVA without space suit possible?
« Reply #23 on: 02/26/2011 01:47 am »
Pipe would have a tight seal on the mouth.

Not feasible, there is the nose, ears and eye sockets where the air would leak out
« Last Edit: 02/26/2011 01:49 am by Jim »

Offline Jim

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Re: Is EVA without space suit possible?
« Reply #24 on: 02/26/2011 01:48 am »

For me, it looks like there is a chance that lungs will not fail in a matter of minutes and they have perhaps more time.


no,there isn't a chance.  Give it up.
« Last Edit: 02/26/2011 01:49 am by Jim »

Offline telomerase99

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Re: Is EVA without space suit possible?
« Reply #25 on: 02/26/2011 02:27 am »
Physician here, Jim's right again. No matter how good the seal is around the mouth (not that the seal could be very good becuase of the pressure gradient) whatever air is on it's way to the longs would immediately be sucked out to the vacuum of space. The pressure in the lungs would be so low that consciousness would be lost in... the historical 15 seconds.

Now, if the subject were intubated (with breathing tube to trachea) the difference in pressure from inside the lungs and outside would rupture the trachea and we would be right back to square one. The breathing tube seal is maintained by a donut shaped balloon that is inflated to not greater than 15mmHg. I suppose that the vacuum could result in a collapse of tissues around the tube throughout its length and this might buy you some time, but how are you going to get intubated in the vacuum of space?

Even if you could be, when patients are left on too light of sedation they describe conscious intubation as an extremely unpleasant experience:(

Offline RedSky

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Re: Is EVA without space suit possible?
« Reply #26 on: 02/26/2011 02:35 am »
As soon as I saw this thread, I thought back to my childhood and that classic line: "Open the pod bay door, HAL".  My father had taken me to the big theater in NYC where 2001 A Space Odyssey had just opened.  You got a little program book that week, and I noticed a printed page insert: It described NASA and military tests on decompression to a vacuum, and a potential to survive for 15-25 seconds. Whether true or not, they clearly were responding to criticism at the time on the scene where Poole enters the Discovery without his helmet.  Here's the classic (rather plodding but still suspenseful) scene:


Offline vh5150

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Re: Is EVA without space suit possible?
« Reply #27 on: 02/26/2011 03:15 am »
Actually, the scene in 2001: A Space Odyssey where the astronaut "transfers" from the pod bay door in an unpressurized state is possibly one of the more accurate portrayals in the whole movie.  If my memory serves, he's exposed to vacuum for a very brief period of time.  The bigger question is whether the vestibule he wound up in could have repressurized so quickly...  A more accurate presentation would have at least given him bleeding tympanic membranes and likely very red eyes from rupture of scleral blood vessels!
Exploration will endure...

Offline DeanG1967

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Re: Is EVA without space suit possible?
« Reply #28 on: 02/26/2011 04:36 am »
"Is EVA without space suit possible?"

Answer is 100% yes...you can (you could put a human in space without pressurization)

The real question is will you remember it?

Answer is 100%....NO....you would be dead quit quickly

Offline KelvinZero

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Re: Is EVA without space suit possible?
« Reply #29 on: 02/26/2011 08:36 am »
Wow, I didn't know that the movie of the incident exists!



On the one hand you have to admire the men who are pushing the boundaries for us.. on the other hand did it remind anyone else of all those "Myotonic goat" videos? :)
« Last Edit: 02/26/2011 09:02 am by KelvinZero »

Offline Colds7ream

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Re: Is EVA without space suit possible?
« Reply #30 on: 02/26/2011 08:52 am »
Actually, the scene in 2001: A Space Odyssey where the astronaut "transfers" from the pod bay door in an unpressurized state is possibly one of the more accurate portrayals in the whole movie.  If my memory serves, he's exposed to vacuum for a very brief period of time.  The bigger question is whether the vestibule he wound up in could have repressurized so quickly...  A more accurate presentation would have at least given him bleeding tympanic membranes and likely very red eyes from rupture of scleral blood vessels!
It is indeed quite accurate as I understand it, with the exception that instead of holding his breath, Bowman should have completely emptied his lungs lest they explode. I read somewhere that Clarke said that had he been on set that day, even that error wouldn't have been made.

"Is EVA without space suit possible?"

Answer is 100% yes...you can (you could put a human in space without pressurization)

The real question is will you remember it?

Answer is 100%....NO....you would be dead quit quickly
The perfect example here being the crew of Soyuz 11, I guess...
« Last Edit: 02/26/2011 08:53 am by Colds7ream »

Offline I14R10

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Re: Is EVA without space suit possible?
« Reply #31 on: 02/26/2011 09:08 am »
There are number of things that would kill you.
1) radiation
2) lack of pressure (blackout within 20 seconds, death within 3 minutes)

Offline Nikola

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Re: Is EVA without space suit possible?
« Reply #32 on: 02/26/2011 12:00 pm »
I wonder what's the pressure inside of this hot water bottle:


Offline vh5150

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Re: Is EVA without space suit possible?
« Reply #33 on: 02/26/2011 03:39 pm »
Would you be willing to climb inside this and have me push you out of an airlock?  Although it is somewhat reminiscent of the "rescue balls" proposed at one time as a way to transfer astronauts from a crippled orbiter to a rescue ship!
Exploration will endure...

Offline kkattula

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Re: Is EVA without space suit possible?
« Reply #34 on: 02/26/2011 04:53 pm »
Hot water bottles are tested to 14 kpa.

And I suspect the pressure to inflate is generated by palate, cheeks and lips, not lungs. Lungs can't handle enough pressure differential.

Offline Robotbeat

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Re: Is EVA without space suit possible?
« Reply #35 on: 02/27/2011 07:26 am »
Hot water bottles are tested to 14 kpa.

And I suspect the pressure to inflate is generated by palate, cheeks and lips, not lungs. Lungs can't handle enough pressure differential.
Lungs can handle around 1-2psi, I believe.
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Offline gospacex

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Re: Is EVA without space suit possible?
« Reply #36 on: 02/27/2011 08:48 pm »
Physician here; have dealt with a few patients from scuba accidents (too rapid ascent).

Is it applicable analogy for pressure drop from 1/5 atm pure oxygen to zero pressure? 1/5 atm pressure change is equivalent to 2 meter ascent only.

Offline Robotbeat

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Re: Is EVA without space suit possible?
« Reply #37 on: 02/27/2011 08:54 pm »
I have a couple questions, here...

Unconsciousness occurs within ~15 seconds during exposure to vacuum. This happens because the vacuum in the lungs causes blood passing through the lungs to out-gas any oxygen to the lungs and the 15 seconds is roughly how long it takes for this oxygen-poor blood to reach the brain, correct? (I know this may not be exactly precise, so please correct me.)

I've already read enough of vacuum exposure, so I desire response from those with particular knowledge, not just encyclopedic knowledge.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline JohnFornaro

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Re: Is EVA without space suit possible?
« Reply #38 on: 02/28/2011 01:16 am »
I would say yes, for a few seconds.  Maybe a minute.  But I gotta go now.
Sometimes I just flat out don't get it.

Offline vh5150

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Re: Is EVA without space suit possible?
« Reply #39 on: 02/28/2011 02:20 am »
Robotbeat:  You're basically correct, you're describing the oxygen/hemoglobin dissociation curve I mentioned a few posts back...  Essentially, the hemoglobin can no longer avidly bind the oxygen in vacuum, resulting in severe hypoxia (very low oxygen levels in the blood).  Eventually, if the brain continues to receive such oxygen poor blood, unconsciousness rapidly ensues, usually within the quoted 15-45 seconds.  More prolonged such conditions lead to irreversible anoxic encephalopathy (brain death).  Well before this would occur, however, death would more likely have occurred due to gas bubble embolus resulting in acute cardiac arrest (which is why we NEVER inject air into the arterial circulation in surgical or critically ill patients).  If you ever want a major lawsuit as a physician, inject 10 cc or so of air into someone's arterial line!!  Yikes!!  Has about the same effect as injecting concentrated potassium chloride quickly...

Basically, to put an end to speculation in this thread, EVA without a pressurized spacesuit is incompatible with survival for more than 15-45 seconds, no matter how long you condition yourself prior or what type of off the shelf equipment you try to utilize.  There is a reason spacesuits haven't changed fundamentally much since the Gemini/Apollo days.  Physics and biochemistry dictate the level of sophistication needed to keep humans alive in the vacuum and oven/deep freeze/radiation environment of space.  It's always gonna be that way, folks.
Exploration will endure...

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