STS-127 Prelaunch Thread,July 11 7:39 PM EDT

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Just for scheduling purposes; tanking begins at ~ 8:15 PM EDT. (0015 UT June 17) . NASA TV will cober tanking beginning at 8PM EDT.
The point where the hydrogen leak problem has occurred will be between 11:10 and 11:15 PM EDT, during LH2 topping and LH2 replenish. We will know by then if the problem has been fixed.

NASA Launch coverage begins at 12:30 AM EDT (0430 UT)

Launch is scheduled for 5:40 AM EDT (0940 UT)

MW

 

[CalliArcale]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Not sure which you're referring to here, Calli. The STS-127 launch will be a standard 51.6 degree launch up and off the east coast. LRO will launch due east and complete less than 1 full orbit before the lunar burn.

I was taking Shuttle, but both of those are nice. ;-) I was wondering if STS-127 would be launching ascending or descending, and if there'd be a chance for folks on the East Coast to see it. I've heard of people watching it from places like North Carolina. Since it'll be going up the eastern seaboard, anybody know how far inland you can actually see it?

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

The shuttle ISS missions always launch up the east coast. I have seen in from near the NJAA in NW NJ, but that won't happen this time; it's 12 minutes after sunrise here It's also been cloudy for the whole month of June. My poor baby tomato plants have had exactly 12 hours of sun this month, it's rained 12 of 16 days.

Along the lower southeast coast, it is before sunrise, so it's worth a look. It might be clear as far north as Charleston, SC. Sunrise there is 6:11 AM EDT.

 

[3488]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Latest entry from Spaceflightnow. Justin Ray.


2215 GMT (6:15 p.m. EDT)
T-minus 6 hours and holding. Countdown clocks have just paused for a planned two-hour hold prior to fueling of space shuttle Endeavour.

During this hold, the Mission Management Team will gather for its readiness meeting at 7:30 p.m. to give approval for fueling while the launch team determines if there are any constraints with loading the shuttle's external tank starting at 8:15 p.m. tonight.

Launch remains scheduled for 5:40 a.m. EDT tomorrow.

Spaceflightnow. Justin Ray.

So far it's looking good, but then fuelling has not yet commenced. Hopefully this time there will be no scrub.

It's getting late here, good night everyone.

Andrew Brown.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

As of about 9 PM EDT, tanking has not started due to potential lightning near the pad. There's a little while left that the loading can start before the 5:40 AM EDT launch slides off the table.
This means it will be at least an hour later before we know whether the hydrogen leak has been fixed. (i.e. 00:15 AM EDT rather than 23:15)

I'm trying to find out how late the tanking can begin for a 5:40 AM launch, no firm answer yet...

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Well time is running out to begin tanking...the latest they've ever gone before is a few minutes from now, about 10PM EDT. They are looking at ways to shave a few more minutes off, but if we don't start soon, this will be a scrub

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

It's getting awfully close to scrub time

With 3 hours for tanking (1:15 AM EDT, then inspection and crew loading), we have to be minutes away from a scrub.
Certainly no more than 15 minutes, and witn thunder still being heard on the pad feed, it doesn't look good. Hope I'm wrong....but I fear I am not.

 

[spacefire]

Re: STS-127 Pre Launch Thread -- June 13 ppd

looks like they might scrub, says my inside source

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

I don't think they have a choice.wooooooo that last lightning strike sealed the deal for me

 

[vulture4]

Re: STS-127 Pre Launch Thread -- June 13 ppd

The rain as sopped, i think they just have time to go ahead.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread,July 11 7:39 PM EDT

I can't believe they can start tanking at 11 PM EDT and get the crew loaded starting 20 minutes after tanking is completed, but so far it seems they they are going to try....

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Unbelieveably, at 11:05 PM EDT, go fo fueling....

 

[newsartist]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Unbelieveably, at 11:05 PM EDT, go fo fueling....

...until the gasseous H2 leak came back.

Scrub until July.

 

[3488]

Re: STS-127 Pre Launch Thread -- June 13 ppd

A great shame, better safe then sorry.

Seems strasnge that even that tremendous work carried out to resolve this issue yeasterday, it still has not been & it looks like it will be a major repair.

BTW it's MeteorWayne's Birthday today. Happy Birthday Wayne :mrgreen: :mrgreen: .

Andrew Brown.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Thanx Andrew

From what was said this leak was different. It occurred much earlier in the fill, when nothing should have even been venting into the system from that location.

 

[bobble_bob]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Such a shame about the launch, any plans for a conference on Nasa TV today?

Im really getting concerned that they wont have time to fly the remaining shuttle missions by the time its due to retire. 8 missions in 14 months is going to be tight

Happy birthday Wayne. Hope you have a good one despite no launch

 

[davf]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Well said: better safe than sorry.

For the benefit of anyone who might want to go see a launch and worry about postponement, the staff at the KSC visitor center were great. Everything was open and ramped up except for the bus tours. One of the security people said to me: "It's kind of like a big slumber party." and that was a good description of it. A great place to watch it from... and unique to be in the center overnight like that. While disappointed about the scrub, it was still a good experience. And besides, LRO / LCROSS is scheduled for tomorrow aft.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

From Spaceflightnow:

http://www.spaceflightnow.com/shuttle/s ... 619update/

Excerpts:

Minor defect in shuttle fuel tank might be causing leaks
BY WILLIAM HARWOOD


A very slight "clocking" misalignment in the way a hydrogen vent port flange on the shuttle Endeavour's external tank was riveted into the structure is the leading candidate for what caused gaseous hydrogen leaks that derailed two launch attempts June 13 and 17, the shuttle program manager said today.

The use of a different type of seal where a launch pad vent line attaches to the side of the external tank may resolve the problem. The alternative seal design should provide a tighter fit that is less susceptible to the temperature-related mechanical shrinkage and motion that can put uneven stress on the interface and lead to leaks.

To find out, engineers are making plans for a fueling test at launch pad 39A, loading Endeavour's tank with super-cold hydrogen rocket fuel and measuring leak rates where the vent line connects to the side of the tank. The leaks typically show up when the mechanism is subjected to cryogenic temperatures.

.....
Engineers at Lockheed Martin's external tank plant in Michoud, La., are making plans to replace the current rigid Teflon seal with the alternative flexible two-part seal, evaluating washer-like shims on the umbilical plate's mounting hardware to further counteract the clocking misalignment.

......
When Endeavour's tank was delivered from the assembly plant, "they were doing measurements and that flange on the ET side is cocked counter-clockwise .65 degrees," Shannon said.

"What has happened, we are pretty sure, is that when you put that external plate with the line on it onto the ET flange, there's a pyrotechnic bolt that holds those two together. It's above that round pipe. That whole system can rotate about that pyro bolt. If the two plates are in perfect alignment, it's not going to rotate, it'll just move slightly up and down. But since it is cocked a little bit ... it pulls the entire structure to the right (when the hardware contracts at cryogenic temperatures) and that allows a leak on the left side."

 

[bobble_bob]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Hopefully this is the cause. Strange that replacing the plate worked on the previous mission if this is the root cause

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

They didn't replce the plate in the previous repair, just the seal.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Just a reminder NASA will conduct a tanking test tomorrow morning to verify the repair for the hydrogen leaks.

It is scheduled to start at 7 AM EDT (1100 UT/GMT) and be on NASA TV.

The original problems occurred just under 3 hours in, the last launch attempt problems occurred earlier ~ 1 1/2 to 2 hours after tanking started.

MW

 

[roocnu]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Thanks for the reminder, MW.
Am tuned in to spaceflightnow.com at the moment - should know by about 9am if the test is successful. Looks like a beautiful morning in Florida.
Katrina

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Looks like a successful test. The tank will be unloaded starting around noon. If all continues to go well, all should be clear for a launch 10 days from now on July 11th at 7:39 PM EDT.

There will be a news conference at 1PM EDT.

 

[MeteorWayne]

Re: STS-127 Pre Launch Thread -- June 13 ppd

Just watched the post tanking test news conference...things went REALLY well. They understand the problem (tolerance buildup and miniscule misalignments) and have two things in place incorporated in the fix. Very close examination of the alignment, and modification of the seal to a design that had been tried before.

As to performance, the allowable limit is 40,000 ppm of hydrogen; both tanking failures had levels of 60,000 ppm.

The reading on this test was 12 ppm, effectiveily zero (12 ppm is the lowest that can be detected)

So all appears good, they even sent out the ice inspection team as they would in a normal launch (which had not been done during the attempts because the failure scrubbed the launch too early) so everything is on track for a July 11 launch. The countdown will pick up next Wednesday.

MW

 

[shuttle_guy]

Re: STS-127 Pre Launch Thread -- June 13 ppd

The tanking test went very well, however if I had had a vote it would have been to go for the launch. It is expensive to do a tanking test, it damages the tank foam (loading then draining causes the foam to form cracks and somtimes worse damage is caused), and the tanking test exposes the program to the loss of the vehicle due to a on pad explosion or fire.