CAIB depressurization finding and Virgin Galactic

When I was rereading the PDF about the fate of Columbia's crew for the
info on the titanium burning, I ran into the part about how fast the
depressurization incapacitated them, either from anoxia causing them to
go almost instantly unconscious, or a combo of that and the bends from
the nitrogen in their blood boiling at the low pressure altitude of the
cabin once it depressurized.
We were discussing what the effects would be if Virgin Galactic's Space
Ship 2 suffered loss of cabin pressure at near the top of its trajectory
during flight, and in the case of Columbia the astronauts were
incapacitated so fast that they were not even able to lower the visors
on their pressure suits to activate the suit oxygen systems, despite
fairly low g loads of only around 3.5 when the cabin lost pressure. (the
visors were left open during reentry, because otherwise the pure oxygen
used by the suit breathing system would vent into the cabin as they
exhaled, and could build up to a concentration high enough to pose a
fire threat.)
So unless Virgin Galactic would fly its passengers in fully buttoned-up
pressure suits, loss of pressure at full altitude would lead to them
being incapacitated in around 6 seconds. Fatal vacuum exposure follows
around 30 seconds after that occurs according to the report:
http://www.nasa.gov/pdf/298870main_SP-2008-565.pdf

Pat

On Mon, 12 Apr 2010 12:14:45 -0800, Pat Flannery
wrote:

So unless Virgin Galactic would fly its passengers in fully buttoned-up
pressure suits, loss of pressure at full altitude would lead to them
being incapacitated in around 6 seconds.

People routinely fly in airliners at 30-35,000 feet. A sudden loss of
pressure might be nasty there too. Maybe we should wear fully
buttoned-up pressure suits above the third floor?

Dale

Pat Flannery wrote:

At those altitudes what happens is you go unconscious, and the crew can
don their oxygen masks and quickly dive the aircraft to lower altitude
where everyone will awaken again, though some may have ruptured eardrums
if they had any plugging of their eustachian tubes.

Passengers can do absolutely nothing, suits or no suits.

On 4/12/2010 10:00 PM, Dale Carlson wrote:


People routinely fly in airliners at 30-35,000 feet. A sudden loss of
pressure might be nasty there too. Maybe we should wear fully
buttoned-up pressure suits above the third floor?

At those altitudes what happens is you go unconscious, and the crew can
don their oxygen masks and quickly dive the aircraft to lower altitude
where everyone will awaken again, though some may have ruptured eardrums
if they had any plugging of their eustachian tubes.
At altitudes above 63,000 feet, the nitrogen dissolved in your blood
goes into gaseous form, causing extreme pain, stopping your blood
circulation, and rupturing the blood capillaries of your lungs so that
they fill with blood. About 30-40 seconds exposure to hard vacuum and
you are either dead or mortally injured...provided you were breathing a
oxygen-nitrogen atmosphere...if you were breathing a pure oxygen one for
a hour or so before the depressurization occurred, the nitrogen will
have washed out of your blood, so it won't boil, and you could survive
the experiance longer, though brain damage from anoxia would set in
fairly quickly.
Space Ship 2 has a major difference from a airliner; once the engine
burns out it coasts ballisticly out of the atmosphere and then falls
back into it. So you can't dive it to a lower altitude like an airliner
if something goes wrong - you have to wait till it falls back into the
lower atmosphere over six minutes* later.
That means that any pressure loss on the way up at above 63,000 feet is
going to last long enough to kill anyone onboard who isn't wearing a
pressure suit.

* Six minutes is the time in weightlessness, so for at least that long
you are on a unpowered ballistic lob with minimal atmospheric effects.

Pat

Neil Gerace wrote:
Pat Flannery wrote:

At those altitudes what happens is you go unconscious, and the crew
can don their oxygen masks and quickly dive the aircraft to lower
altitude where everyone will awaken again, though some may have
ruptured eardrums if they had any plugging of their eustachian tubes.

Passengers can do absolutely nothing, suits or no suits.

Nor do they need to.

--
Greg Moore
Ask me about lily, an RPI based CMC.

On 4/13/2010 4:52 AM, Neil Gerace wrote:
Pat Flannery wrote:

At those altitudes what happens is you go unconscious, and the crew
can don their oxygen masks and quickly dive the aircraft to lower
altitude where everyone will awaken again, though some may have
ruptured eardrums if they had any plugging of their eustachian tubes.

Passengers can do absolutely nothing, suits or no suits.

Passengers and crew can at least breathe till the rocketship falls back
into the lower atmosphere. At that point things become problematic as
far as survival goes, but at least they have some chance of being alive
at the end of the flight if damage is limited enough that it can still
be glide landed. Without pressure suits, loss of cabin pressure after
engine shutdown during ascent is a automatic death sentence.

Pat

On 4/13/2010 6:32 AM, Greg D. Moore (Strider) wrote:
Neil Gerace wrote:
Pat Flannery wrote:

At those altitudes what happens is you go unconscious, and the crew
can don their oxygen masks and quickly dive the aircraft to lower
altitude where everyone will awaken again, though some may have
ruptured eardrums if they had any plugging of their eustachian tubes.

Passengers can do absolutely nothing, suits or no suits.

Nor do they need to.

Well, they could probably try to scream a little as their blood boiled
and they lost consciousness...but in space no one can hear you scream.
That might make an interesting corporate motto for Virgin Galactic. :-)
I still like William Shatner's response to a possible trip on Space Ship 2:
"I'm interested in man's march into the unknown but to vomit in space is
not my idea of a good time. Neither is a fiery crash with the vomit
hovering over me."
http://www.dailymail.co.uk/tvshowbiz...dly-space.html
Maybe Tim Allen?
If nothing else, Virgin Galactic promises to return the excitement to
air travel not seen since the great days of the hydrogen filled
passenger dirigibles, where just being alive at the end of the fight was
seen as a joyous event for all involved.

Pat