Shuttle launch scrubbed again

Still leaking hydrogen:
http://spaceflightnow.com/shuttle/sts127/090617scrub/
Now expected to be launched on July 11.

Pat

On Wed, 17 Jun 2009 01:34:53 -0500, Pat Flannery
wrote:

Still leaking hydrogen:
http://spaceflightnow.com/shuttle/sts127/090617scrub/
Now expected to be launched on July 11.

....Yep. Full scrub. Post-scrub news conference NET 2:30 CDT. Damn
cheap Auto Zone valve kits.


OM
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Should be a pretty obvious they need to stand down and fix this. Imagine
what would have occurred here if this was the rescue mission for Hubble?

There is a history to this, besides 119. As I recall, they have, more than
once had to cycle a valve and after this the leak goes away, but not always.
As they seem not to understand the mechanism, the fix can hardly be found.
I'd suggest two things. First officially apply for an extension to Shuttle
flights to the following April, so the pressure is reduced.
Then tak this system on this Shuttle and run it under realistic conditions
with more instrumentation. I was going to say, its not rocket science to
find a leak, but in this case it is!

You do not simply want to refill and empty the tank as it will mean the foam
will fall off at launch.

Cost wise, the money has mostly been spent so a short extension will be
minimal cost in the vast scheme of things. You do not want to not fly some
missions as you have the hardware and need to manifested items so I see not
real problem.

As for actually cause, its obviously some contraction/hardening/moisture
freezing int the system problem as far as one can tell.

Brian

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"OM" wrote in message
...
On Wed, 17 Jun 2009 01:34:53 -0500, Pat Flannery
wrote:

Still leaking hydrogen:
http://spaceflightnow.com/shuttle/sts127/090617scrub/
Now expected to be launched on July 11.

...Yep. Full scrub. Post-scrub news conference NET 2:30 CDT. Damn
cheap Auto Zone valve kits.


OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

Brian Gaff stelde de volgende uitleg voor :
Should be a pretty obvious they need to stand down and fix this. Imagine what
would have occurred here if this was the rescue mission for Hubble?
The rescue mission was to be launched on pad 39a, not 39b. The problem
is not the ET, but a plate on the pad (as far as I know!!)

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On Wed, 17 Jun 2009 21:05:56 +0200, André, PE1PQX
wrote:

Brian Gaff stelde de volgende uitleg voor :
Should be a pretty obvious they need to stand down and fix this. Imagine what
would have occurred here if this was the rescue mission for Hubble?
The rescue mission was to be launched on pad 39a, not 39b. The problem
is not the ET, but a plate on the pad (as far as I know!!)

It would have been the same GUCP, which is installed on the Tank in
the VAB (but remains behind with the pad after liftoff.) However, it
might be that connecting/disconnecting/reconnecting for the switch
from 39B to 39A had something to do with it.

Brian

Brian Gaff wrote:
Should be a pretty obvious they need to stand down and fix this. Imagine
what would have occurred here if this was the rescue mission for Hubble?



In that case I'd assume they would launch it, leaking hydrogen or not.

There is a history to this, besides 119. As I recall, they have, more than
once had to cycle a valve and after this the leak goes away, but not always.
As they seem not to understand the mechanism, the fix can hardly be found.
I'd suggest two things. First officially apply for an extension to Shuttle
flights to the following April, so the pressure is reduced.
Then tak this system on this Shuttle and run it under realistic conditions
with more instrumentation. I was going to say, its not rocket science to
find a leak, but in this case it is!


I keep wondering if the problem is at the pad end, not the ET end.
Although not the safest thing to do, they should have someone with a
hydrogen sniffer and a thermal imaging system go up by the tank vent and
then start filling it, so he could look for cold spots in the area of
the vent and pin down exactly where the hydrogen is leaking from.
About the only ET variable I can think of is that I assume these are
tanks built after hurricane Katrina, so was some slip made in their
construction?

You do not simply want to refill and empty the tank as it will mean the foam
will fall off at launch.


Surprisingly that didn't occur the last time they did multiple fillings,
although one would think it would have that effect.
But these aborted launches are expensive, and they should figure out
what's going wrong before trying it again.
Another approach would be to take the whole vent line assembly off of
the other pad and move it over to this one to see if that helps.

Cost wise, the money has mostly been spent so a short extension will be
minimal cost in the vast scheme of things. You do not want to not fly some
missions as you have the hardware and need to manifested items so I see not
real problem.

As for actually cause, its obviously some contraction/hardening/moisture
freezing int the system problem as far as one can tell.


They seem to be leaning in that direction also. But why didn't this
happen more often on earlier missions?
One problem with keeping the Shuttle on the pad for any length of time
is this is thunderstorm season at the Cape, and we don't want a repeat
of the hail damage to the foam on the ET. A severe thunderstorm occurred
in the evening just a few days ago and went over the Cape.
Let's hope things go better for tomorrow's LRO launch.

Pat

Pat Flannery writes:

Another approach would be to take the whole vent line assembly off of the
other pad and move it over to this one to see if that helps.


Esp. since that pad is now undergoing mods for Orion/Aries I and won't be used
for shuttles again anyways.

Dave

In sci.space.history message
a.com, Wed, 17 Jun 2009 07:16:58, Brian Gaff
posted:
There is a history to this, besides 119. As I recall, they have, more than
once had to cycle a valve and after this the leak goes away, but not always.
As they seem not to understand the mechanism, the fix can hardly be found.
I'd suggest two things. First officially apply for an extension to Shuttle
flights to the following April, so the pressure is reduced.

No date should be set. NASA obviously want, under present long-term
plans, to finish with STS; they should be told to do the presently-
planned flights, including AMS, without either avoidable delay or any
haste or any time limit.

Then tak this system on this Shuttle and run it under realistic conditions
with more instrumentation.

AIUI, hydrogen is leaking out into the atmosphere from a jointed pipe at
slightly higher pressure; the other end of the pipe discharges to
atmosphere.

The solution is to put a fan in the pipe, well away from the shuttle,
that blows outwards so that the pressure in the pipe at the dodgy joint
is that of the atmosphere outside; that will reduce the leak rate
greatly. The pressure differential can be measured with a U-tube of
coloured paraffin (or colored kerosene) observed with a small camera;
the equipment can be destroyed at launch. Alternative to a fan - a
steam-jet or air-jet pump.

Possibly the root cause is that the pad is bent.

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Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
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On Jun 16, 11:34*pm, Pat Flannery wrote:
Still leaking hydrogen:http://spaceflightnow.com/shuttle/sts127/090617scrub/
Now expected to be launched on July 11.

Pat

Hmmmmmmmmmmmmmm. I leak hydrogen myself, occasionally (actually a
hydrogen compound, CH4). It's usually legumes that does it me,
however, so it's probably no help. (Especially roasted peanuts-in-the-
shell!!! hmmmmmmmmmmmmm- peanuts...)

Seriously, as far as I ever heard, Endy was never rolled off the pad
after the most recent Hubble mission, so did they install everything
on the pad or were they considering launching a rescue mission with
all the ISS mission stuff aboard?

On Thu, 18 Jun 2009 13:12:51 -0700, cfleon wrote:

On Jun 16, 11:34Â*pm, Pat Flannery wrote:
Still leaking
hydrogen:http://spaceflightnow.com/shuttle/sts127/090617scrub/ Now
expected to be launched on July 11.

Pat

Hmmmmmmmmmmmmmm. I leak hydrogen myself, occasionally (actually a
hydrogen compound, CH4). It's usually legumes that does it me, however,
so it's probably no help. (Especially roasted peanuts-in-the- shell!!!
hmmmmmmmmmmmmm- peanuts...)

Al Gore and Obama are going to tax your ass.

Seriously, as far as I ever heard, Endy was never rolled off the pad
after the most recent Hubble mission, so did they install everything on
the pad or were they considering launching a rescue mission with all the
ISS mission stuff aboard?