ISS O2 questions?

http://www.msnbc.msn.com/id/7912095/page/2/

Why "burn" the somewhat infamous lithium perchlorate cannisters before
using the O2 from tanks on Quest? Is the Quest reserve especially difficult
to replace under current circumstances?

JJ Robinson II
Houston, TX

The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out -- weighing a lot more
than just the gas.



"JJR2" wrote in message
.. .
http://www.msnbc.msn.com/id/7912095/page/2/

Why "burn" the somewhat infamous lithium perchlorate cannisters before
using the O2 from tanks on Quest? Is the Quest reserve especially
difficult
to replace under current circumstances?

JJ Robinson II
Houston, TX

Jim Oberg wrote:
The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out -- weighing a lot more
than just the gas.


It would also require payload bay space, which is becoming a scarce
resource, and (based on the STS-104 EVA timeline) might require an EVA
for each pair of tanks. Each tank weighs 1200 lbs...

http://www.shuttlepresskit.com/STS-1...5.htm#TIMELINE

I don't recall seeing a Quest tank replacement in any of the manifests
through current assembly complete. I realize we haven't put the "hit"
on the resources due to the problem with Quest hardware ruining the
EMUs, but it's hard for me to believe that we would have been able to go
through the entire original assembly sequence on the initial set of
tanks. Anyone remember if one was in the schedule?

I'm also curious how many flight tanks have been completed (beyond the
four already flying)...

--
I was punching a text message into my | Reed Snellenberger
phone yesterday and thought, "they need | GPG KeyID: 5A978843
to make a phone that you can just talk | rsnellenberger
into." Major Thomb | -at-houston.rr.com

"JJR2" wrote in message
.. .
http://www.msnbc.msn.com/id/7912095/page/2/

Why "burn" the somewhat infamous lithium perchlorate cannisters before
using the O2 from tanks on Quest? Is the Quest reserve especially
difficult
to replace under current circumstances?

Yes. You'll note that the space shuttle has been grounded for quite some
time now.

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

"Reed Snellenberger" wrote in message
.. .
Jim Oberg wrote:
The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out -- weighing a lot more
than just the gas.


It would also require payload bay space, which is becoming a scarce
resource, and (based on the STS-104 EVA timeline) might require an EVA
for each pair of tanks. Each tank weighs 1200 lbs...

http://www.shuttlepresskit.com/STS-1...5.htm#TIMELINE

I don't recall seeing a Quest tank replacement in any of the manifests
through current assembly complete. I realize we haven't put the "hit"
on the resources due to the problem with Quest hardware ruining the
EMUs, but it's hard for me to believe that we would have been able to go
through the entire original assembly sequence on the initial set of
tanks. Anyone remember if one was in the schedule?

I'm also curious how many flight tanks have been completed (beyond the
four already flying)...

--
I was punching a text message into my | Reed Snellenberger
phone yesterday and thought, "they need | GPG KeyID: 5A978843
to make a phone that you can just talk | rsnellenberger
into." Major Thomb | -at-houston.rr.com

So, there's literally no backup plan for refilling the tanks from other
sources? Were the "current circumstances" on ISS really that difficult to
imagine?

JJ Robinson II
Houston, TX

"Reed Snellenberger" wrote
I'm also curious how many flight tanks have been completed (beyond the
four already flying)...

I'm curious as to what instrumentation there is on the tanks
to verify pressures. Anybody have access to the telemetry master list?

Jim Oberg wrote:

The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out

The Shuttle has twice replenished the tanks already. There is plumbing
in relevant modules to link a PMA to Quest and plumbing in the ODS to
allow an O2 linkup between shuttle and station.

The Quest is equipped with high pressure pumps that draw O2 from
shuttle's tanks and compress it into the quest O2 tanks at much higher
pressure than the O2 stored on shuttle. I am not certain, but I assume
that the same process can be made using N2.

There is no need to replace the Quest tanks.

In terms of the original questions:

For whatever reason, the USA segment has never used Quest O2 for cabin
replishment. Obviously, once Shuttle was grounded, the lack of ability
to replenish the tanks has made the O2 in the tanks very valuable and
would be used only to support EVAs. (and I suspect NASA has been very
happy that its own EVA suits were "inop" and all EVAs performed via
Russian airlock).

The burning of candles is simple: Candles have an expiry date. Rather
than return them in a progress and have them burn up on re-entry, it is
best to use them before their expiry date, and thus preserve the O2 in
the progress tanks.

"John Doe" wrote in message ...
Jim Oberg wrote:

The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out

The Shuttle has twice replenished the tanks already. There is plumbing
in relevant modules to link a PMA to Quest and plumbing in the ODS to
allow an O2 linkup between shuttle and station.

The Quest is equipped with high pressure pumps that draw O2 from
shuttle's tanks and compress it into the quest O2 tanks at much higher
pressure than the O2 stored on shuttle. I am not certain, but I assume
that the same process can be made using N2.

There is no need to replace the Quest tanks.

While what you say is true, this proces takes O2 (and presumably N2) from
the same tanks that the shuttle uses for its own life support. Without
something like an EDO pallet, the ammount you can transfer to ISS on each
shuttle flight will be very limited. Unfortunately, I believe the only EDO
pallet NASA had was lost with Columbia and I doubt NASA (or Congress) would
want to spend the money to build another, when the shuttle is scheduled to
be retired when ISS assembly is complete.

Out of curiosity, how is the connection made between the O2 supply on the
shuttle and ISS?

I'm wondering how easy it would be for another docked vessel to make the
same connection. It would be a good thing to have this sort of resupply
done by a new commercial vehicle, since CEV will be a long time coming, will
likely be expensive to fly, and it will be busy doing other things anyway.

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

"John Doe" wrote
The Shuttle has twice replenished the tanks already. There is plumbing
in relevant modules to link a PMA to Quest and plumbing in the ODS to
allow an O2 linkup between shuttle and station.

Super-thanks, and once again, people I trust
(even with fake names) have saved me from more than
my fair share of public embarrassment....

On Fri, 20 May 2005 13:07:15 -0400, John Doe wrote:

Jim Oberg wrote:

The Quest tanks, as I understand it, are very expensive to replenish.
There is no way to refill them from PLB tanks. Instead, the entire
'doghouse' tankage must be swapped out

The Shuttle has twice replenished the tanks already. There is plumbing
in relevant modules to link a PMA to Quest and plumbing in the ODS to
allow an O2 linkup between shuttle and station.

The Quest is equipped with high pressure pumps that draw O2 from
shuttle's tanks and compress it into the quest O2 tanks at much higher
pressure than the O2 stored on shuttle. I am not certain, but I assume
that the same process can be made using N2.

There is no need to replace the Quest tanks.



That question beings to mind another question.

What percentage of the airlock air (O2 and N2) is recovered when the
airlock is depressurized? The percentage that is pumped back into the
Space Station before the vents are opened to the vacuum? And conversely,
what percentage of air is lost when the vent is opened?

How does this compare to the Russian airlock?

--
Craig Fink
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