From: henry@zoo.toronto.edu (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Potentialy stupid question: human in space
Date: Wed, 11 Oct 1995 14:53:59 GMT

In article <45crt7$gf@s1.GANet.NET> "William H. Mook, Jr." <wm0@s1.GANet.NET> writes:
>This isn't science, but Arthur Clarke wrote a story about a group of 
>interplanetary passengers crossing from one ship to another.  One gets 
>the impression that as long as your lungs are properly evacuated, and as 
>long as your blood has oxygen in it, and as long as you stay out of 
>sunlight, you could spend several minutes (okay a minute) in hard vacuum.

Clarke was too optimistic, alas.  The survival time in vacuum is quite
a bit shorter than the time available on Earth when holding your breath.
In the first place, when you are holding your breath -- even when you
are holding it *out* rather than *in* -- most of your oxygen reserve is
in your lungs, not in your blood.  In the second place, when your lungs
contain vacuum, you are *losing* oxygen out through the lungs at quite
a rate; the stuff diffuses out just about as well as it diffuses in.

The best Earthly comparison is what happens to people who walk into a room
containing a pure-nitrogen atmosphere.  The analogy is fairly good; to a
first approximation, when there's no oxygen present, it doesn't matter
whether something else is there or not.  Such accidents happen
occasionally in industry.  (In fact, one happened at the Ariane 5 launch
site a few months back.)  Sudden loss of consciousness occurs within
10-15s, and death follows quickly.  Stringent precautions have to be taken
to prevent such accidents, because survival is rare -- you get no warning
that you're about to keel over, and rescuers must understand the situation
immediately and act very quickly.

Also, Clarke got one detail completely wrong:  hyperventilating first will
not help.  The bloodstream of a resting person is already saturated with
oxygen; there is no way to pump more in.  What hyperventilation does is to
flush CO2 out of your body.  This matters because the breathing reflex is
triggered by CO2 buildup, not oxygen shortage.  (That's why you get no
warning of impending unconsciousness in a pure-nitrogen atmosphere.)
Hyperventilation suppresses the breathing reflex so you can fully exploit
the air in your lungs.  This doesn't help in vacuum.

(I suppose I should also observe here that deliberate hyperventilation to
help you hold your breath -- in situations like diving -- is dangerous,
for an analogous reason:  it's possible to suppress your breathing reflex
so thoroughly that you run out of oxygen before you feel any need to
breathe, and the result is sudden unconsciousness.)
-- 
The problem is, every time something goes wrong,   |       Henry Spencer
the paperwork is found in order... -Walker on NASA |   henry@zoo.toronto.edu

From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.tech
Subject: Re: Survival in a Vaccuum
Date: Sat, 10 Aug 1996 15:43:01 GMT

In article <320A7E4A.8E6@squid.stmarys.ca> Jamie Stensrud <j_stensr@squid.stmarys.ca> writes:
>> >>This is purely from memory. If I recall correctly, as long as you
>> >>don't hold your breath you can remain conscious for 30-45 seconds in 
>> >>a total vacuum; at this point you pass out, and 2-3 minutes later...
>> >The general idea is right but the numbers are probably too optimistic.
>> >10-15 seconds of useful consciousness and a minute of survival...
>
>Actually, you're both wrong...

You might want to do a wee bit of research -- beyond just watching movies
and reading sunday-supplement articles -- before saying that.  A good place
to start would be "Rapid (Explosive) Decompression Emergencies in Pressure-
Suited Subjects", Emanuel Roth, NASA CR-1223 (1968).

>If a human were to be placed in a pure 
>vaccuum, there would be no way the lungs would be able to resist the 
>incredible negative pressure; all air would be forced from the lungs 
>within a second...

More to the point, you don't *want* to try to resist:  internal pressure
of circa 1psi is enough to cause lung rupture, which is a major medical
emergency that's quite likely to kill you even if you survive the vacuum
exposure.  (Yes, it is quite possible to resist strongly enough to cause 
this; ask any properly-trained scuba diver.)

>Also, the blood would boil (yes, boil) as the oxygen in it was forced 
>out, and blood would erupt from various places, such as the eyes and 
>ears.

You've been watching too many movies.  The Soyuz 11 cosmonauts spent
several minutes in vacuum when their capsule lost pressure before reentry. 
Their bodies showed so little damage that the recovery crew started CPR,
and it took a careful investigation to establish the cause of death (they'd
also spent a then-unprecedented 24 days in space, and initial speculation
was that the sudden return to gravity might have killed them).

>The person would have only a few seconds of lucidity, and would be dead 
>within 30 seconds, most likely less.

On 14 Dec 1966, a NASA spacesuit technician spent circa 20 seconds in
vacuum when a suit hose failed in a vacuum-chamber test.  He lost
consciousness after 12-15 seconds, but regained it when the chamber was
repressurized.  Not only did he survive, but he appears to have suffered
no substantial injury, and he had only the most minor symptoms afterward.
See the Roth report for details.
-- 
 ...the truly fundamental discoveries seldom       |       Henry Spencer
occur where we have decided to look.  --B. Forman  |   henry@zoo.toronto.edu

From: "Geoffrey A. Landis" <geoffrey.landis@lerc.nasa.gov>
Newsgroups: sci.space.tech,rec.arts.sf.science
Subject: Re: Survival in a Vaccuum
Date: 2 Aug 1996 13:32:31 GMT

In article <31FF9610.5355@interconnect.net> Sean Sutherland,
maverick@interconnect.net writes:
>I'm wondering if anyone here could settle something for me.  Awhile back, 
>I seem to remember reading something about survival in a vaccuum.  The 
>text, which was a "list of common space myths" said, along with things 
>like the nonexistance of zero-g chambers and other stuff I already knew, 
>that survival in a vaccuum was possible for, I believe, a few minutes.  
>What causes death, according to the text, was blood boiling, as the body 
>can stay intact.  I'm wondering if anyone can confirm this or tell me it 
>ain't so.  Thanks.

Every six months this question gets asked.  Consult the sci.space FAQ;
it's discussed in great detail there.

Briefly, survival in vacuum is probably possible for a minute or so. 
Consciousness will go away much more rapidly than that.

 from _Bioastronautics Data Book_, Second edition, NASA SP-3006, edited
by James F. Parker and Vita R. West, 1973, in the article "Chapter 1:
Barometric Pressure," by Charles E. Billings:

page 5, (following a general discussion of low pressures and ebullism):
[on decompression to vacuum] "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."

____________________________________________
Geoffrey A. Landis,
Ohio Aerospace Institute at NASA Lewis Research Center
physicist and part-time science fiction writer

Newsgroups: sci.space.science
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: Survival in a vacuum
Date: Thu, 10 Jul 1997 14:14:45 GMT

In article <33C21956.869306A@netdoor.com>,
menendez  <menendez@netdoor.com> wrote:
>Full vaccum is only 15psi, which isn't enough to cause nitrogen bubbles
>in blood, which is what happened to that guy in the Bond movie.

Actually, a drop from 14.7psi to zero *is* enough to cause some trouble
with nitrogen coming out of solution.  In fact, some of the pre-shuttle
astronauts had minor problems with the transition from 14.7psi to 5psi --
Michael Collins says he had pain in one knee for a little while on both
his flights.

However, there simply isn't enough dissolved gas in your blood to do
anything very spectacular.  It can hurt you, and in extreme cases kill you
(if you get a substantial gas bubble in your heart), but it won't make
your body explode or anything like that.

Movies should not be relied on for technical information.  (The business
about an airliner exploding if a bullet pierces its skin is also from a
Bond movie, and it too is pure fiction.)
--
Committees do harm merely by existing.             |       Henry Spencer
                           -- Freeman Dyson        |   henry@zoo.toronto.edu

From: "Geoffrey A. Landis" <geoffrey.landis@lerc.nasa.gov>
Newsgroups: sci.space.tech
Subject: Re: survial in a vacuum
Date: 27 Jun 1998 15:54:42 GMT

This is a topic that comes up frequently on sci.space and
rec.arts.sf.science.

The quick answers to these questions are: Clarke got it about right in
2001.  You would survive about a ninety seconds, you wouldn't explode,
you would remain conscious for about ten seconds.

The best data I have comes from _Bioastronautics Data Book_, Second
edition, NASA SP-3006, edited by James F. Parker and Vita R. West, 1973,
in the article "Chapter 1: Barometric Pressure," by Charles E. Billings.
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):
"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."

Henry Spencer suggests the book by Arnauld E. Nicogossian, Carolyn L.
Huntoon and Sam L. Pool _Space Physiology and Medicine_, 2nd Edition, Lea
and Febiger, Philadelphia 1989.

Another useful reference is
"Rapid (Explosive) Decompression Emergencies in Pressure-Suited
Subjects", by Emanuel M. Roth, NASA CR-1223, circa 1968.  Its focus is on
decompression, rather than vacuum exposure per se, but it still has a lot
of good info.

There are three cases of human exposure to vacuum worth noting.  In 1966
a technician at NASA Houston was decompressed to vacuum in a space-suit
test accident.  This case is discussed by Roth in the reference above.
He lost consciousness in 12-15 seconds.  When pressure was restored after
about 30 seconds of exposure, he regained consciousness, with no apparent
injury sustained.

In 1960, in a balloon-jump, another vacuum exposure for longer term but
not for a whole-body exposure occurred:
"The experiment of exposing an unpressurized hand to near vacuum for a
significant time while the pilot went about his business occurred in real
life on Aug. 16, 1960.  Joe Kittinger, during his ascent to 102,800 ft
(19.5 miles) in an open gondola, lost pressurization of his right hand.
He decided to continue the mission, and the hand became painful and
useless as you would expect.  However, once back to lower altitudes
following his record-breaking parachute jump, the hand returned to
normal."
[quoting from Leonard Gordon, _Aviation Week_,  February 13th 1996.

Finally, posting to sci.space, Gregory Bennett discussed an actual space
incident:

"Incidentally, we have had one experience with a suit puncture on the
Shuttle flights.  On STS-37, during one of my flight experiments, the
palm restraint in one of the astronaut's gloves came loose and migrated
until it punched a hole in the pressure bladder between his thumb and
forefinger.  It was not explosive decompression, just a little 1/8 inch
hole, but it was exciting down here in the swamp because it was the first
injury we've ever head from a suit incident.  Amazingly, the astronaut in
question didn't even know the puncture had occured; he was so hopped on
adrenalin it wasn't until after he got back in that he even noticed there
was a painful red mark on his hand.  He figured his glove was chafing and
didn't worry about it....  What happened: when the metal bar punctured
the glove, the skin of the astronaut's hand partially sealed the opening.
 He bled into space, and at the same time his coagulating blood sealed
the opening enough that the bar was retained inside the hole."

More details can be found in the sci.space FAQ:
http://www.cis.ohio-state.edu/hypertext/faq/usenet/space/top.html
and at a site at NASA Johnson:
http://medlib.jsc.nasa.gov/intro/vacuum.html
(which quotes liberally [and without credit] from the old discussiona on
sci.space)

________
Geoffrey A. Landis
Ohio Aerospace institute at NASA Lewis Research Center
http://www.sff.net/people/Geoffrey.Landis/

From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.science
Subject: Re: naked person in space - freeze or fry?
Date: Tue, 19 May 1998 01:09:43 GMT

In article <ant171755d07M+4%@gnelson.demon.co.uk>,
Graham Nelson  <graham@gnelson.demon.co.uk> wrote:
>> Assorted movies and other unreliable sources notwithstanding, exposure to
>> vacuum is not immediately harmful except for the absence of oxygen...
>
>Can you scuba-dive in space, then, and last a reasonable length of
>time?

Unfortunately, it doesn't look feasible.  I should have qualified my
original statement slightly:  "*if* you don't try to hold your breath".
The minimum useful oxygen pressure in the lungs is well above the level
where lung rupture becomes a serious risk unless there is some outside
pressure as well.  Surviving vacuum at the cost of lung rupture is not
much of an improvement; lung rupture is a life-threatening medical
emergency because it injects gas bubbles into your bloodstream.

(It turns out that one possibly-effective first-aid measure for
bloodstream gas bubbles -- in a gravity field! -- is simply to put you in
a head-down orientation.  That encourages gas bubbles which reach the
heart to gather in the "footward" part of the heart chambers, where they
are relatively harmless, rather than lingering in the vicinity of the
valves at the "headward" end of the heart, where they can interfere with
the valve action and stop circulation.)
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu

From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.science
Subject: Re: naked person in space - freeze or fry?
Date: Wed, 20 May 1998 18:31:27 GMT

In article <35646576.4514020@news.mira.net.au>,
Roger Riordan <riordan@werple.net.au> wrote:
>>...No, 1.5psi of oxygen will not keep you conscious.
>
>An old school physics book indicates the pressure at the top of Mt
>Everest is ~ 5.5psi, so partial pressure of oxygen would be about
>1.1psi.  And this is sufficient to permit fairly strenuous exercise.

The numbers are about right, but the implication is dubious.  That
pressure is sufficient for light exercise, *after lengthy acclimation*,
at some risk of permanent brain damage due to oxygen starvation.  Even
Sherpas wear oxygen for climbing Everest.  Doing it without oxygen is
strictly for lunatics (one or two of whom have done it); it's at the
extreme limit of human survival even with the best possible preparation.

>So shouldn't 1.5psi of oxygen keep you alive, at least for a short
>period?

There are some total-pressure effects involved too.  In particular, the
air entering the lungs is diluted somewhat by CO2 and water vapor emerging
from the lung wall, and that dilution is more or less an absolute amount,
*not* proportional to pressure.  So available oxygen is rather less for
pure oxygen at that pressure than for normal air with that oxygen partial
pressure.  You lose about 0.9psi to water vapor and another 0.7psi to CO2
under normal conditions.  So at 1.5psi -- a level of lung overpressure
which is high enough to be seriously dangerous -- there nominally would be
no oxygen at all in the gas at the lung wall!  The CO2 penalty can be (and
automatically is) reduced somewhat by faster breathing to reduce body CO2
levels, but that only buys you about 0.2psi improvement -- probably not
enough to produce a net inward flow of oxygen.

Without acclimation, you need about 1.15psi of oxygen *at the lung wall*
for clear thinking.  So about 2.5psi is the minimum useful pressure, and
that much lung overpressure is nearly suicidal.  (I don't have current
references on pressure breathing, but a fairly old one indicates that
1psi is considered about tops even in emergencies.)
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu

From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.science
Subject: Re: naked person in space - freeze or fry?
Date: Wed, 20 May 1998 18:37:46 GMT

In article <35615855.1709463D@mail.nerc-essc.ac.uk>,
dwcp  <dwcp@mail.nerc-essc.ac.uk> wrote:
>> The minimum useful oxygen pressure in the lungs is well above the level
>> where lung rupture becomes a serious risk unless there is some outside
>> pressure as well.
>
>I assume that the outside pressure could be provided by a strong, close-
>fitting, elastic garment. Unfortunately you couldn't put it on.
>Putting it on under atmospheric pressure would squeeze all your
>breath  out (as it would be providing *additional* pressure)...

Not difficult to fix:  put a thin contoured airbag between the garment and
your chest, filled to the point where its full-expansion internal pressure
matches the intended breathing pressure.

That's what was done in the 1960s "skinsuit" experiments, which seriously
explored a spacesuit built along those lines.  The idea had promise --
vacuum-chamber tests of prototype suits were basically successful -- but
it was never explored fully enough to determine whether its remaining
engineering problems were completely solvable.
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu

From: Henry Spencer <henry@zoo.toronto.edu>
Newsgroups: sci.space.science
Subject: Re: naked person in space - freeze or fry?
Date: Mon, 25 May 1998 01:59:12 GMT

In article <6k0rrk$et7$1@news.metronet.de>, Markus Mehring <m.m@gmx.net> wrote:
>>There is a known case of a man spending 20-30s in vacuum -- in a
>>vacuum-chamber accident during Apollo spacesuit development -- without
>>any detectable damage (apart from being unconscious until pressure was
>>restored).
>
>Who was this poor guy?

As far as I know, his name is not public information.  The incident was
not widely publicized and it's hard to find out about it, but there is
some info in obscure NASA reports, notably CR-1223, "Rapid (Explosive)
Decompression Emergencies in Pressure-Suited Subjects", a 1969 study of
decompression hazards and treatment methods.
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu

From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: survial in a vacuum
Date: Mon, 6 Jul 1998 14:05:15 GMT

In article <6ngs2k$2fg@er7.rutgers.edu>,
Nicholas Landau <nlandau@eden.rutgers.edu> wrote:
>>What kills someone exposed to vacuum is simply lack of oxygen.  Everything
>>else happens much more slowly.
>
>When people are exposed to lesser degrees of decompression, they are
>known to suffer "the bends."  This is a frequently fatal condition
>caused by the formation of nitrogen (N2) bubbles forming in the
>blood.  I would expect he same thing would happen if the cause of
>decompression were loss of a spacecraft's atmosphere.

Yes, but again this comes under the heading of "everything else happens
much more slowly".  Lack of oxygen will knock you out within 15-20s and
kill you within a minute or so (much more quickly than on Earth, because
there is no air in your lungs and in fact you're *losing* oxygen from the
blood through the lungs).  The most the bends will do during that time is
to add some discomfort.  The bubbles take time to form and coalesce.

>In the case of the Suez mission, pressure may have dropped too slowly
>for such symptoms to appear.

Uh, no, not by orders of magnitude.  At the very low (by diving standards)
pressures involved, bends-free loss of pressure would take hours.
--
Being the last man on the Moon is a |  Henry Spencer   henry@spsystems.net
very dubious honor. -- Gene Cernan  |      (aka henry@zoo.toronto.edu)