Re: Outer Space Exposure

Endiaferon 

eyharistw,

Di




--- In [email protected], "Demetrius Kiminas" <constantinople@...> 
wrote:
>
> Se orismenes tainies exoyme dei 'atyxous' diastimanthropous
> na ektithontai sto keno tou diastimatos kai na skane san 
> mpalonia h na pagonoun stigmiaia san na mpikane se super
> katapsykti.
> 
> Ti pragmatika symvainei otan ena atomo ektethei sto
> keno? Vrika ena sxetiko arthro pou pistevo na endiaferei...
> 
> Xairetismous,
> Dimitris
> 
> Outer Space Exposure
> Posted by Alan Bellows on November 27th, 2006 at 6:51 am 
> In scores of science fiction stories, hapless adventurers find 
themselves unwittingly introduced to the vacuum of space without 
proper protection. There is often an alarming cacophony of screams 
and gasps as the increasingly bloated humans writhe and spasm. Their 
exposed veins and eyeballs soon bulge in what is clearly a 
disagreeable manner. The ill-fated adventurers rapidly swell like 
over-inflated balloons, ultimately bursting in a gruesome spray of 
blood.
> 
> As is true with many subjects, this representation in popular 
culture does not reflect the reality of exposure to outer space. Ever 
since humanity first began to probe outside of our protective 
atmosphere, a number of live organisms have been exposed to vacuum, 
both deliberately and otherwise. By combining these experiences with 
our knowledge of outer space, scientists have a pretty clear idea of 
what would happen if an unprotected human slipped into the cold, 
airless void.
> 
> In the 1960s, as technology was bringing the prospect of manned 
spaceflight into reality, engineers recognized the importance of 
determining the amount of time astronauts would have to react to 
integrity breaches such as a damaged spacecraft or punctured space-
suits. To that end, NASA constructed an assortment of large altitude 
chambers to mimic the hostile environments found at varying distances 
above the Earth, accounting for factors such as air pressure, 
temperature, and radiation. Adventurous volunteers were subjected to 
simulations of the conditions found several miles up, and a handful 
of animal tests were conducted with even lower pressures. 
> 
> Using the data from these experiments and their knowledge of outer 
space, scientists were able to make some reasonable conclusions about 
how the human body would respond to sudden depressurization. A series 
of accidents over the years proved most of their extrapolations to be 
accurate. In 1965, in a space-suit test gone awry, a technician in an 
altitude chamber was exposed to a hard vacuum. The defective suit was 
unable to hold pressure, and the man collapsed after fourteen 
seconds. He regained consciousness shortly after the chamber was 
repressurized, and he was uninjured. In a later incident, another 
technician spent four minutes trapped at low pressure by a 
malfunctioning altitude chamber. He lost consciousness and began to 
turn blue, but escaped death when one of the managers kicked in one 
of the machine's glass gauges, allowing air to seep into the chamber.
> 
> In 1971, three Russian cosmonauts aboard an early Soyuz spacecraft 
tragically experienced the vacuum of space first-hand, as described 
in the Almanac of Soviet Manned Space Flight:
> 
> ".the orbital module was normally separated by 12 pyrotechnic 
devices which were supposed to fire sequentially, but they 
incorrectly fired simultaneously, and this caused a ball joint in the 
capsule's pressure equalization valve to unseat, allowing air to 
escape. The valve normally opens at low altitude to equalize cabin 
air pressure to the outside air pressure. This caused the cabin to 
lose all its atmosphere in about 30 seconds while still at a height 
of 168 km. In seconds, Patsayev realized the problem and unstrapped 
from his seat to try and cover the valve inlet and shut off the valve 
but there was little time left. It would take 60 seconds to shut off 
the valve manually and Patsayev managed to half close it before 
passing out. Dobrovolsky and Volkov were virtually powerless to help 
since they were strapped in their seats, with little room to move in 
the small capsule and no real way to assist Patsayev. The men died 
shortly after passing out. [.] The rest of the descent was normal and 
the capsule landed at 2:17 AM. The recovery forces located the 
capsule and opened the hatch only to find the cosmonauts motionless 
in their seats. On first glance they appeared to be asleep, but 
closer examination showed why there was no normal communication from 
the capsule during descent."
> When the human body is suddenly exposed to the vacuum of space, a 
number of injuries begin to occur immediately. Though they are 
relatively minor at first, they accumulate rapidly into a life-
threatening combination. The first effect is the expansion of gases 
within the lungs and digestive tract due to the reduction of external 
pressure. A victim of explosive decompression greatly increases their 
chances of survival simply by exhaling within the first few seconds, 
otherwise death is likely to occur once the lungs rupture and spill 
bubbles of air into the circulatory system. Such a life-saving 
exhalation might be due to a shout of surprise, though it would 
naturally go unheard where there is no air to carry it. 
> 
> In the absence of atmospheric pressure water will spontaneously 
convert into vapor, which would cause the moisture in a victim's 
mouth and eyes to quickly boil away. The same effect would cause 
water in the muscles and soft tissues of the body to evaporate, 
prompting some parts of the body to swell to twice their usual size 
after a few moments. This bloating may result in some superficial 
bruising due to broken capillaries, but it would not be sufficient to 
break the skin. 
> 
> Within seconds the reduced pressure would cause the nitrogen which 
is dissolved in the blood to form gaseous bubbles, a painful 
condition known to divers as "the bends." Direct exposure to the 
sun's ultraviolet radiation would also cause a severe sunburn to any 
unprotected skin. Heat does not transfer out of the body very rapidly 
in the absence of a medium such as air or water, so freezing to death 
is not an immediate risk in outer space despite the extreme cold. 
> 
> For about ten full seconds- a long time to be loitering in space 
without protection- an average human would be rather uncomfortable, 
but they would still have their wits about them. Depending on the 
nature of the decompression, this may give a victim sufficient time 
to take measures to save their own life. But this period of "useful 
consciousness" would wane as the effects of brain asphyxiation begin 
to set in. In the absence of air pressure the gas exchange of the 
lungs works in reverse, dumping oxygen out of the blood and 
accelerating the oxygen-starved state known as hypoxia. After about 
ten seconds a victim will experience loss of vision and impaired 
judgement, and the cooling effect of evaporation will lower the 
temperature in the victim's mouth and nose to near-freezing. 
Unconsciousness and convulsions would follow several seconds later, 
and a blue discoloration of the skin called cyanosis would become 
evident.
> 
> At this point the victim would be floating in a blue, bloated, 
unresponsive stupor, but their brain would remain undamaged and their 
heart would continue to beat. If pressurized oxygen is administered 
within about one and a half minutes, a person in such a state is 
likely make a complete recovery with only minor injuries, though the 
hypoxia-induced blindness may not pass for some time. Without 
intervention in those first ninety seconds, the blood pressure would 
fall sufficiently that the blood itself would begin to boil, and the 
heart would stop beating. There are no recorded instances of 
successful resuscitation beyond that threshold.
> 
> Though an unprotected human would not long survive in the clutches 
of outer space, it is remarkable that survival times can be measured 
in minutes rather than seconds, and that one could endure such an 
inhospitable environment for almost two minutes without suffering any 
irreversible damage. The human body is indeed a resilient machine.
> 
> Further reading:
> Wikipedia article on Hypoxia
>




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