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Old July 15th 18, 07:34 PM posted to sci.space.policy
Jeff Findley[_6_]
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Default Soyuz fueling

In article ,
says...

The NASA PR guy just mentioned the Soyuz was fueled several hours ago.

From a LOX point of view, I take it that they decided to fuel before
crew ingress (in this case, a Progress so no crew) ?

If you load the LOX hours before launch, is there a substantial cost to
replenish what you lose during those hours, or is this a minimal cost?

From a LOX density point of view, once it is loaded and starts to boil
off, does it basically remain at same density whether you launch an hour
or 3 hours later? Aka: does it warm tup to some level and then
stabilizes at that tempoerature as it boils off?


If you're going to launch (presumably hours) after fueling, keeping the
LOX below the boiling point would be very difficult. Launch vehicles
that do this typically let the LOX boil off and just continuously
replenish with liquid oxygen to make up for the boil off. Most US
launch vehicles have done it this way.

SpaceX Falcon is the exception. They sub-cool the LOX to well below its
boiling temperature to increase its density. Hence the "load and go"
timing of LOX filling.

BTW, the NASA guy now refers to Cygnus as a Northrop Grunman spacecraft.
Mentions that the Cygnus has been given the go-ahead to reboost the ISS.


Yes. NASA is finally testing reboost of ISS with Cygnus. From what
I've read, this first reboost is only about a minute long test.

Another tidbit: Today's progress will get to ISS after only 2 orbits, a
record.


Yes. A record that Russia can perform with very little investment of
hard cash. They really don't have the cash to do much of significance
these days. It's looking less and less likely that all of the planned
Russian modules will ever make it to ISS. Modules decades in the making
are still being assembled.

Jeff
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