O2 and N2 on US segment without shuttle

Right now, the US segment depends on the shuttle to connect to PMA2,
hookup a few pipes so that the station can draw O2 and N2 from the
shuttle and replenish the tanks on Quest. Those not only service EVA
activities, but also are meant to provide breathable atmosphere to the
US segment.

So far, they haven't made use of the Quest air for cabin atmosphere
mostly because the station size and reduced crews have made it possible
for the russian systems to cope, even during failures of Elektron.

However, by 2010, the station will be bigger, perhaps with bigger crews.

Has NASA committed to the CEV being able to dock to PMA2 and provide O2
and N2 to refill station tanks ?

Has NASA outlined any plans to allow Quest to replenish its tanks for
operations between the last shuttle flight and the first CEV flight
(assuming CEV actually is built) ?

For instance, if NASA intends to have tanks shipped by Progress or ATV,
NASA would have to send/install additional hardware inside of Quest to
allow it to draw the gases from portable tanks. Such hardware would have
to be sent by shuttle before its last flight, so it would have to
already be in the planning stanges at least to reserve up-lift mass in
what appears to be very limited spare capacity for the remaining shuttle flights.

And if CEV never flies, does NASA have any contingenies to keep the USA
segment going ?

On Wed, 13 Sep 2006 01:41:41 -0400, John Doe wrote:

So far, they haven't made use of the Quest air for cabin atmosphere
mostly because the station size and reduced crews have made it possible
for the russian systems to cope, even during failures of Elektron.

However, by 2010, the station will be bigger, perhaps with bigger crews.

Has NASA committed to the CEV being able to dock to PMA2 and provide O2
and N2 to refill station tanks ?

Didn't NASA just deliver a U.S. oxygen generator system on STS-121 in
July?

Brian

Brian Thorn wrote:
Didn't NASA just deliver a U.S. oxygen generator system on STS-121 in
July?


Unit has yet to be turned on. So we don't know if it will work, for how
long it will work, and once it starts to fail, how often it will fail.
Secondly, this unit cannot be used to refill the tanks in Quest.

EVAs not only require the O2 from the Quest tanks to fill the suit's
tank, but also to compensate for the air lost by airlock (only a portion
of the air in airlock is recuperated, the rest is vented to space).

And in the case of a fire, I assume that the tanks would be heavily
relied upon to renew the cabin atmosphere ASAP once the fire is out.

So, at this point in time, only a very limited number of EVAs can be
planned beyond 2010 because Quest will become totally useless without
the Shuttle.

And even if that CEV thing is ever built, I dount that they would be
able to conduct EVAs from a CEV while docked to the station, which means
they need to use Quest for EVAs, which means they must find a way to
replenish those tanks.

"John Doe" wrote in message ...
So, at this point in time, only a very limited number of EVAs can be
planned beyond 2010 because Quest will become totally useless without
the Shuttle.

And even if that CEV thing is ever built, I dount that they would be
able to conduct EVAs from a CEV while docked to the station, which means
they need to use Quest for EVAs, which means they must find a way to
replenish those tanks.

Even more interesting to me is this quote from a James Oberg article:

High-pressure gas tanks attached to the exterior of the Quest
airlock also contain significant quantities of compressed oxygen.
But this would be the last resource to be expended, because the gas
tanks are very expensive to recharge. The weight of the high-pressure
pumps in the space shuttle cargo bay far exceeds the weight of the gas
to be reloaded into them.

Doing ISS EVA's from the shuttle airlock means you don't have to carry the
high pressure pumps on the shuttle to replenish the Quest tanks. It seems
like the better place for those pumps would be on ISS so that you could use
any low pressure O2 and N2 supply to recharge the tanks (Progress, ATV, HTV,
COTS, CEV, and etc).
Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

Jeff Findley wrote:
Even more interesting to me is this quote from a James Oberg article:

High-pressure gas tanks attached to the exterior of the Quest
airlock also contain significant quantities of compressed oxygen.
But this would be the last resource to be expended, because the gas
tanks are very expensive to recharge. The weight of the high-pressure
pumps in the space shuttle cargo bay far exceeds the weight of the gas
to be reloaded into them.


The high pressure pumps are in fact in Quest. The pumps that are on the
shuttle are not strong enough to reach the pressures needed for the
Quest tanks. One of the reasons that it is called the "joint" airlock
is that those refilling high pressure pumps are russian (and this noisy).

The problem is that of plumbing. The plumbing is between Quest and PMA2.
So Unity, destiny and Node2 are outfitted with the O2 and N2 pipe and
interconnects to allow Quest to draw gases from whatever is attached to PMA2.

On Wed, 13 Sep 2006 23:03:05 -0400, John Doe wrote:

And even if that CEV thing is ever built, I dount that they would be
able to conduct EVAs from a CEV while docked to the station, which means
they need to use Quest for EVAs, which means they must find a way to
replenish those tanks.

Sounds like a likely job for COTS or the unmanned CEV Cargo variant
that NASA seems to be planning again...

Brian

"John Doe" wrote in message ...
The high pressure pumps are in fact in Quest. The pumps that are on the
shuttle are not strong enough to reach the pressures needed for the
Quest tanks. One of the reasons that it is called the "joint" airlock
is that those refilling high pressure pumps are russian (and this noisy).

I didn't know this.

The problem is that of plumbing. The plumbing is between Quest and PMA2.
So Unity, destiny and Node2 are outfitted with the O2 and N2 pipe and
interconnects to allow Quest to draw gases from whatever is attached to
PMA2.

So is this plumbing that's permanently outfitted to those modules and only
those modules and how easy would it be to use a different CBM to do resupply
of O2 and N2. I'm wondering this because the COTS proposals I've seen so
far plan to use CBM's to attach to ISS.

Jeff
--
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor
safety"
- B. Franklin, Bartlett's Familiar Quotations (1919)

Jeff Findley wrote:
So is this plumbing that's permanently outfitted to those modules and only
those modules and how easy would it be to use a different CBM to do resupply
of O2 and N2. I'm wondering this because the COTS proposals I've seen so
far plan to use CBM's to attach to ISS.

I am not certain if the plumbing for high pressure O2/N2 to refull Quest
tanks is specific to the Unity-Destiny, Destiny-Node2 and Node-2-PMA2
CBM connections. It is quite possible that all CBMs in Unity might have
possible connections for the high pressure O2/N2 back into Quest.

I do know that there is a general O2 distribution pipe thourghout the
USA segment (aka: DEstiny's ECSLL can command O2 release in any US
segment module).