Spacesuit question

This is probably a stupid question, but why can't they just move the Orlan
suits from the Pirs to the Quest Airlock instead of going out the Pirs and
having to translate all that distance to the Destiny module?

"Bill Porter" wrote in message
...
This is probably a stupid question, but why can't they just move the Orlan
suits from the Pirs to the Quest Airlock instead of going out the Pirs and
having to translate all that distance to the Destiny module?

The Quest airlock is still missing some necessary equipment needed to
support Orlan EVA's.

Jeff
--
Remove icky phrase from email address to get a valid address.

On Wed, 30 Jun 2004 11:11:08 -0400, "Jeff Findley" wrote:
"Bill Porter" wrote in message
.. .
This is probably a stupid question, but why can't they just move the Orlan
suits from the Pirs to the Quest Airlock instead of going out the Pirs and
having to translate all that distance to the Destiny module?

The Quest airlock is still missing some necessary equipment needed to
support Orlan EVA's.

Ok, so they suit up in Pirs, go on internal oxygen and power, then traverse
the station IVA (IntraVehicularActivity), and egress via the Quest airlock.
That would keep them inside, out of vacuum, solar heat loads, and micrometeor
hazard, until they were near their objective. Of course navigating the interior
of the station in suits might present its own hazards.

Gary

Of course navigating the interior
of the station in suits might present its own hazards.

Gary

it might be necessary some day in a emergency.

the russian suits are only supported br russian modules and vice versa.

someday these incompatibilties are going to be looked at closely by a safety
investigation
HAVE A GREAT DAY!

They can go on internal power and oxygen...but there's a third thing
you need: cooling. You generate a lot of heat in a space suit. I'm
not sure how the ORLAN cooling system works, but if it's anything like
the EMU, you need to be on umbilical or in a vacuum.

Like what?

Of course, the Quest Airlock was specifically designed to support both
EMUs and ORLANs.

wrote in message
...
Of course, the Quest Airlock was specifically designed to support both
EMUs and ORLANs.


This is true, but it currently lacks some necessary equipment needed to
support an EVA using Russian suits.

Anyone who's really interested in the details can look them up themselves.
Google is your friend (and does newsgroup as well as Internet searches).

Jeff
--
Remove icky phrase from email address to get a valid address.

Bill Porter wrote:

This is probably a stupid question, but why can't they just move the Orlan
suits from the Pirs to the Quest Airlock instead of going out the Pirs and
having to translate all that distance to the Destiny module?

Going from 14.7 PSI indoors to 0 PSI outdoors requires a slow decompression.
Astronauts go from 14.7 to about 4 or 5 PSI (forget which is used on Russian
suits) of pure oxygen.

The transition takes time. For one thing, the crew needs to follow special
precedures to avoid getting the "bends" (blood releasing disolved nitrogen
which then forms bubbles in your body which are a big problem - think of what
happens when you open a soda bottle).

During that time, the crew has their suits "plugged" into the airlock systems
for power and O2, thus preserving their limited reserves inside their suits.

What you are suggesting would require that once the crew have completed their
acclimatization to pure O2 at 5PSI, they would repressurize the airlock so
they could ingress the station, then go to Quest, close the door and slowly
depressurize that airlock to finally go outside. This would end up taking much
more time than just opening the door in Pirs once theu are at 0 PSI and
walking to the work site. While NASA brags about the station being huge, in
human terms, it isn't THAT big and from Pirs, it isn't THAT far to Z1 where
the CMGs are located.

But this brings up a question:

What happens if a US or Russian EVA suit, ready to go outdoors with pure O2
are ~5 PSI, moves back into 14.7 PSI environment ? Will the crewmember be able
to remain at 5 PSI ? Will the suit be able to continue to maintain a lower
pressure inside the suit than outside environment ?

Gary Coffman wrote in message . ..

Ok, so they suit up in Pirs, go on internal oxygen and power, then traverse
the station IVA (IntraVehicularActivity), and egress via the Quest airlock.
That would keep them inside, out of vacuum, solar heat loads, and micrometeor
hazard, until they were near their objective. Of course navigating the interior
of the station in suits might present its own hazards.

Gary

You should really watch one of these things on NASA TV or the web
stream sometime. What you describe would most likely only work if the
entire station were depressureized (which, BTW would most likely kill
some of the avionics and control systems). Both kinds of spacesuits
use sublimators for cooling, and these are only effective in vacuum.
When inside a closed airlock, they are attached to fluid umbilicals.
Two reasons orlans can't currently use quest, AFAIK, are the two suits
systems use different coolant mixes (orlan is water plus glycol, US is
just water ?) and there isn't an orlan compatable communication system
in quest. Comms while setting up the suits is very useful, to make
sure the crew has followed the checklist and watch suit telemetry.

Aside from the cooling issue, getting out the airlock isn't a matter
of stepping into your suit, pressing the button, and stepping outside.
It takes a significant time, with various steps of depressurization
and leak checks (both of airlock-station and the suits). The suits
themselves operate around 5 PSI w/pure oxygen, while the station runs
around 15 PSI and 20% oxygen. This requires pre-breath of pure oxygen
to avoid the bends. All of the above requires time, which gets us back
to the cooling issue.

That said, the moving from the RS to the US didn't seem to give them
any serious trouble. The Strela is designed to hoist space walkers
around, and looked like a helluva ride. Imagine being on the end of a
very springy 50ft long pole, hanging out out in space...