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We'll refine this thread based on the MMT decision to either go for launch Sunday, or not.
In the meantime, I've written up some of the MMT presentations on L2:
http://www.nasaspaceflight.com/content/?cid=5304
Again, quote heavy, no need to repeat the post-MMT pressers or what other sites have already explained in their articles. We'd rather bring something new to the table, which is via our ability to gain these presentations.
This is the live update thread for the launch. Should we have a successful launch, it will continue as the Flight Day 1 Live Update thread.
Below are the rules for what is always a very busy day on this site (please take note):
Firstly, if you are guest, please note it is reccomended that you create yourself a login, as we protect the site's servers in the event of overloading by making it member only, see here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10291&posts=4&start=1 (membership to the open sections of the site is free).
This is a live update thread, so we do not want any "woo hoo, go Atlantis" comments clogging up the updates. We have a cheerleading thread for your best wishes:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10978&start=1
We also have a seperate weather specific thread, for comments on the status of the pre-launch weather: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=11028&posts=13&start=1
If you are in Florida for the launch and need tips on where to go for best viewing, we have a thread for that: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10458&start=1
All NASA TV video for the mission is available - for free - here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10045&start=1
If you're learning about the Shuttle - and let's face it, we all are unless your Wayne Hale - you are encouraged to ask questions, but please keep them here: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10600&start=1
Moderators will delete - without notification - any posts that do not follow the above request.
God Speed Atlantis.
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Great article. Lots of things I didn't know in there!!
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Wow, big article Chris! Hope we can get it launched this year if all goes to plan... :)
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Thanks, and that was just a summary. There's a lot, lot more.
Waiting on a NET for the post-MMT presser.
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Post-MMT Presser NET 5pm Eastern. But there's a graphic at the press site saying NET 4pm I'm told.
Will update when we know more.
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Just a note on the mention of the launch window from the tail of the previous status thread: the proposal being discussed modifies the window. If the program decides to implement the proposal, hopefully the new, shorter window will be announced/published. (If not, we'd find out during terminal count, again with all those assumptions.)
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I have tried to catch up on the articles and detail on here and L2 but I am confused a bit here. Forgive the redundant question but exactly WHAT is the plan for tomorrows launch - with respect to the sensors? If they tank and see the same failure signature are we done or are they going to Launch anyway? I don't want to get my hopes up that they have a work around when it may be simply a matter of try again and hope the error does not happen again. thank you in advance and again, sorry to be redundant, I just want to get it clear in my head what they are going to realistically attempt tomorrow.
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How does it change the launch time? I thought the proposal just 'eliminated' the spare minutes around the 'best' T-0 so that fuel margins are greatest?
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stockman - 8/12/2007 8:41 PM
I have tried to catch up on the articles and detail on here and L2 but I am confused a bit here. Forgive the redundant question but exactly WHAT is the plan for tomorrows launch - with respect to the sensors? If they tank and see the same failure signature are we done or are they going to Launch anyway? I don't want to get my hopes up that they have a work around when it may be simply a matter of try again and hope the error does not happen again. thank you in advance and again, sorry to be redundant, I just want to get it clear in my head what they are going to realistically attempt tomorrow.
LCC of 4/4 for the LH2 ECOs tomorrow. So any faults, it's a scrub.
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stockman - 8/12/2007 3:41 PM
If they tank and see the same failure signature are we done or are they going to Launch anyway?
Any ECO problems = No Launch.
Every time in the past that they've had ECO problems on the first tanking, all was fine on the second. So if that's the case, they'll go.
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All clear now ... thanks for the quick responses.
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rdale - 8/12/2007 3:42 PM
How does it change the launch time? I thought the proposal just 'eliminated' the spare minutes around the 'best' T-0 so that fuel margins are greatest?
We're saying the time thing; I was too vague. It changes window end, with window open at the in-plane time. They would also be dropping the ability to launch at window open. (Actually not sure if they could still posture for any FD4 rendezvous "panes" or whether those are too far out of plane).
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rdale - 8/12/2007 3:43 PM
stockman - 8/12/2007 3:41 PM
If they tank and see the same failure signature are we done or are they going to Launch anyway?
Any ECO problems = No Launch.
Every time in the past that they've had ECO problems on the first tanking, all was fine on the second. So if that's the case, they'll go.
That is what will allow them to move forward with the new monitoring, as it would be based on experience that ECO works on the second tanking attempt... any failure and its out of that experience base and all bets are off.. scrub,,
window will be shortened.. plan time is the same...
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Today's opening briefing estimate:
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Presser poker time.
I'll see your 4pm and raise you to 4:15pm NET.
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Chris Bergin - 8/12/2007 9:53 PM
Presser poker time.
I'll see your 4pm and raise you to 4:15pm NET.
Now NET 4:30 pm EST.
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This is now the launch day thread, as we understand the MMT has decided to attempt launch on Sunday.
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Rule only applies to LH2 ECO and not LO2?? i.e. LO2 can do weired stuff as long as we have four good tests on LH2 ECO?? and does that exclude all ECO's used for fueling??
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Avron - 8/12/2007 10:16 PM
Rule only applies to LH2 ECO and not LO2?? i.e. LO2 can do weired stuff as long as we have four good tests on LH2 ECO?? and does that exclude all ECO's used for fueling??
If any ECO sensors act up, it's an immediate scrub.
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Chris Bergin - 8/12/2007 3:07 PM
This is now the launch day thread, as we understand the MMT has decided to attempt launch on Sunday.
Indeed, as announced at the KSC press site. They will make a launch attempt tomorrow. MMT meeting has ended and briefing to begin "soon".
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DaveS - 8/12/2007 4:19 PM
Avron - 8/12/2007 10:16 PM
Rule only applies to LH2 ECO and not LO2?? i.e. LO2 can do weired stuff as long as we have four good tests on LH2 ECO?? and does that exclude all ECO's used for fueling??
If any ECO sensors act up, it's an immediate scrub.
Right -- that would be new behavior, too. (No recent history of LOX low-level sensors failing, if not long-term history.)
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The main shuttle page on the NASA.gov portal also reporting the plan now.
http://www.nasa.gov/mission_pages/shuttle/main/
A post MMT news conference on NASA TV is set for approximately 4:30 p.m. EST. The participants will be Wayne Hale, Space Shuttle Program manager, LeRoy Cain, MMT chairman, Doug Lyons, STS-122 launch director, and U.S Air Force Captain Chris Lovett, 45th Weather Squadron.
(The time is obsolete, but the participants aren't.)
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DaveS - 8/12/2007 12:55 PM
Chris Bergin - 8/12/2007 9:53 PM
Presser poker time.
I'll see your 4pm and raise you to 4:15pm NET.
Now NET 4:30 pm EST.
I'll raise PAO's 4:45 to 5:00.
Rats, busted.
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They've dropped the NET; 4:45 pm Eastern for the briefing.
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If we do go tomorrow, NASA TV will do tanking commentry - starting at 6:00am EST (11:00am GMT)
according to NASA STS 122 schedule.
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Now target for 4:45 EST without NET.
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If tanking coverage starts at 6am, how quickly (realisticly) will we find out about issues with the sensors?
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Briefing started and Wayne Hale has the mic.
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"The decision has been made to go forward and we will proceed to tanking tomorrow."
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ntschke - 8/12/2007 4:41 PM
If tanking coverage starts at 6am, how quickly (realisticly) will we find out about issues with the sensors?
Probably wouldn't be too long of a response time (although I'd predict you'll see something here before PAO says).
If I understand correctly, the sensor circuit issues didn't occur immediately after the checks started on Thursday. (It was about 15 minutes after fast fill on the LH2 side.)
If the circuits are behaving normally, not sure how many minutes/hours before the different projects (ET, MPS, etc.) might indicate some confidence.
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Interesting on the change they will bring in on the SSMEs. I'll go after that.
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psloss - 8/12/2007 4:50 PM ntschke - 8/12/2007 4:41 PM If tanking coverage starts at 6am, how quickly (realisticly) will we find out about issues with the sensors?
Probably wouldn't be too long of a response time (although I'd predict you'll see something here before PAO says). If I understand correctly, the sensor circuit issues didn't occur immediately after the checks started on Thursday. (It was about 15 minutes after fast fill on the LH2 side.)
Good point. Of course I'll be checking here, but curious if this would be something that would be pretty much yes or no within the first couple hours tomorrow morning. Crew prep wouldnt start until noon or so right?
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Doug Lyons on schedule...RSS retract at 11 pm local. Tanking (already noted) for 5:55 am local.
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Forecast is only 20% probability of KSC weather prohibiting launch on Sunday.
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Wayne Hale was asked about the engine "changes"...talking about accurate control of the fuel mixture and improved engine flow meters. Directed the main engine project to come back in 2 weeks to get improved flow meters into the flight sets.
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Heh, I'm just now noticing that Wayne is wearing a STS-96 Lead FD shirt. :)
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A launch tomorrow would also be on the day one year after the STS-116 launch. Just another bit of trivia ;)
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Reminder to keep this on updates specific to the launch countdown.
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If they don't get 4/4 LH2 ECO circuits tomorrow, they will scrub but continue collecting data (essentially it becomes a tanking test).
After drain, Doug Lyons saying they would do troubleshooting out at the pad and exhaust those procedures before thinking about a rollback...
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Not a lot of news coming out of Q&A. Currently going over "what ifs" with respect to losing the low-level cutoff system.
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do we have a precise launch time? in case not, why and when we'll know?
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3:21 EDT.
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C5C6 - 8/12/2007 11:38 PM
do we have a precise launch time? in case not, why and when we'll know?
Currently it is 3:21:01 pm EST, this is not set in stone. This will be refined during the T-20 minute and T-9 minute holds tommorow.
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apollo13 - 8/12/2007 11:41 PM
3:21 EDT.
EST! EDT ended a while ago!
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Question in the briefing about the launch window...it will open at the in-plane time and the close will be approx. 60 seconds after that. The duration will be based on how much of a performance loss was agreed on in the plan. (Maybe Chris has that in the L2 docs.) The in-plane time will be finalized during terminal count tomorrow (assuming they get there), but the times already posted online are likely still reasonable approximations.
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I think Doug Lyons said the first SIM test on the LH2 ECOs tomorrow would be when they are covered with propellant...approx. 45 minutes into tanking. (Not sure I heard that right.)
The briefing just concluded.
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Briefing concluded!
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And.. appropriately..
Atlantis at the pad, with sunset in the background. :cool: Hopefully this'll be the last time we'll see this... until she launches again!
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This launch now is on a pretty fundamental level (with regards to the last stand down).
A failure in STS-122's fail safe circuitry (ECO's) has actually increased the level of fail safe failure possibility now
It is good to see that the NASA team have reassured us that when the failsafe circuits go wrong - they go for maximum compliance
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When would the RSS retract have to be to make tanking at ~06:00 EST?
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Mike_1179 - 8/12/2007 6:05 PM
When would the RSS retract have to be to make tanking at ~06:00 EST?
That's roughly an hour before when tanking was on Thursday, so possibly 7:00 PM EST. I'll have my eyes peeled. :)
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Why do they need an RSS when the doors are closed and the module is bolted in?
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Ford Mustang - 8/12/2007 5:06 PMMike_1179 - 8/12/2007 6:05 PMWhen would the RSS retract have to be to make tanking at ~06:00 EST?
That's roughly an hour before when tanking was on Thursday, so possibly 7:00 PM EST. I'll have my eyes peeled. :)
In the conference, they said the RSS would be retracted at 11 p.m. EST, already noted in this thread
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apollo13 - 8/12/2007 5:07 PM
Why do they need an RSS when the doors are closed and the module is bolted in?
This should be in the Shuttle Q&A, but the RSS provides weather protection for the Orbiter and access for workers to get close to it. It contains the Payload Changeout Room, but that is only one of its functions.
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apollo13 - 8/12/2007 6:07 PM
Why do they need an RSS when the doors are closed and the module is bolted in?
The payload installation via the PCR only one of the tasks of the RSS. The RSS contains the OMBUU, which was used to topoff the H2 tanks of the PSRDS.
Weather protection is another task
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Jim - 8/12/2007 5:31 PM
apollo13 - 8/12/2007 6:07 PM
Why do they need an RSS when the doors are closed and the module is bolted in?
The payload installation via the PCR only one of the tasks of the RSS. The RSS contains the OMBUU, which was used to topoff the H2 tanks of the PSRDS.
Weather protection is another task
Plus multiple levels to access all the necessary other locations all along the orbiter body for checks and things like filling the foward and OMS RCS propellents and installing the final closeout TPS locations (as well as removing the orbiter window covers and adding the fwd & aft RCS launch covers).
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By when do they have to lower the beanie cap onto the tank?
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Obviously before they begin tanking 6 AM, EDT, tomorrow morning
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shuttlefan - 8/12/2007 7:49 PM
By when do they have to lower the beanie cap onto the tank?
I'm a bit surprised it's not already in position.
They have to at least have it in place before tanking ops start (ie- preps/chilldowns) just to make sure the seals are verified and the N2 purge flow is operating.
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punkboi - 8/12/2007 9:37 PM Obviously before they begin tanking 6 AM, EDT, tomorrow morning
Punkboi, 6am EST. AM also implies morning.
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RSS Retract to PARK position under way.. Caught this one LATE!
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Get ready to see her!!
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Can't wait for the xenon lights to come on!!
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Ready to fill her up again!!
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too bad they didnt have a live video of the RSS retract. I also caught it late too I thought it was going to start at 11 est but looked at the video feed and it was almost complete. Pretty interesting watching the RSS retract live.
also first time posting but few days lurker! so hello everyone.
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Nice catch, FM. :)
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and illuminated...
100
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NASAGeek - 8/12/2007 9:23 PM
too bad they didnt have a live video of the RSS retract. I also caught it late too I thought it was going to start at 11 est but looked at the video feed and it was almost complete. Pretty interesting watching the RSS retract live.
also first time posting but few days lurker! so hello everyone.
They never do. All the screencaps posted here with every RSS retract are from the NASA KSC video feed webcam page.
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If I'd have known it was starting at 10 instead of 11 (grrr).. I'd have tried to watch the live feed for ya'll and get a video.
Nice picture, mainengine!!! I'd love to see that in person right now!
EDIT: MKremer: I just checked it to make sure.. and thank goodness I did! ;)
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MKremer - 8/12/2007 10:26 PM
NASAGeek - 8/12/2007 9:23 PM
too bad they didnt have a live video of the RSS retract. I also caught it late too I thought it was going to start at 11 est but looked at the video feed and it was almost complete. Pretty interesting watching the RSS retract live.
also first time posting but few days lurker! so hello everyone.
They never do. All the screencaps posted here with every RSS retract are from the NASA KSC video feed webcam page.
Actually wednesday night they did have camera 060 (on the sound supression water tank) on the streaming link for the CIF Roof camera (Channel 12) panned in on the back side of the stack and was catching the RSS retract. Tonight they are still streaming that camera but it is panned in on the LOX sphere. I was hoping that they would have that camera in the same place they did wednesday night.
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Xenon lights are on! She looks marvelous!!!
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hobson911 - 8/12/2007 8:00 PM Actually wednesday night they did have camera 060 (on the sound supression water tank) on the streaming link for the CIF Roof camera (Channel 12) panned in on the back side of the stack and was catching the RSS retract. Tonight they are still streaming that camera but it is panned in on the LOX sphere.
Maybe you'll get to see live footage of the flame that shoots out from the top of the LOX sphere, then :bleh:
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GOX "Beanie" Cap has been placed on top of the ET:
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Could NASA still extend this mission two extra days? I'm doubting since they'll be cutting it close to Christmas.
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Yes. They can even when launch will be delayed to Dec 13.
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dember - 8/12/2007 9:15 PM Could NASA still extend this mission two extra days? I'm doubting since they'll be cutting it close to Christmas.
One of the reasons why the RSS was rolled back to enclose Atlantis on Thursday was to top-off the fuel cells (the liquid hydrogen, to be exact)...so NASA could maintain the two-day extension
And it's New Years Day that NASA is wary of...because of the YERO computer issue, among other things
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They had that same problem with STS-116.
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Looks like maybe a damaged Tyvek cover, or is this just shadow?
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The last ECO sensor comments on this thread apparently were posted several hours ago. However,
some thoughts have occurred to me during the night and I have clipped and posted them below:
------------------------------------------------------------------------------------------------------------------------------------------------------------
Following much of the discussion related to the ECO sensors, several thoughts have surfaced.
First, for background, I do not have L2 info which limits the basis for these comments.
A partial list of concerns follows. [Note: the ordering is not in order of importance.]
The ECO sensor problem is clustered among tanks of relatively recent production. Hence,
tossing reliability numbers around using the total number of tanks ( >100 ) seems to
be improper use of statistics.
There have been less than 300 flights. 3 sigma numbers that are talked about means
approximately (notice I wrote approximately) 1 item in 300 can be outside the limits
and a 3 sigma limit can still be met. That is in the vicinity of 99.7 percent likely
to work. (Somewhere, I thought I saw a claim that 3 sigma was grounds to claim
99.95 percent reliability -- ie., 1 chance in 2000 of failure. I could be wrong, but
it seems to me that it may have been posted somewhere on these threads -- it may have
even been someone merely quoting someone else from off thread -- the point is that
3 sigma -- even widely promulgated by some -- is not failsafe, especially when an
activity consists of a chain of events totally far more than 300.)
The total time over which the sensors have had the opportunity to "malfunction" (?) during
ground tests over recent flights is large (tanks are fueled for hours measured from
start of fast fill to liftoff). Total vehicle flight time with "suspect" sensors is probably
less than an hour. The odds favor no anomalous behavior (so far) during flight time
but rather while on the ground. (An alternate explanation that a root cause might
identify is that the problem can only occur on the ground and in fact is impossible
following liftoff, which includes removing all ground support equipment at the pad
from the equation and, presumably, many of the computers at the launch complex.)
Since erratic sensor behavior is a distinct possibility, it can/should no longer be
considered a failure if sensors act erratically during the ride uphill. What is the
minimum number of failures that might provide *momentary* loss of comm? If the answer is
one, and it takes time to switch to backup equipment or a backup link, the "now
non-failure within family erratic behavior" of the ECO sensors with a comm dropout
leaves the shuttle in a "coin toss' situation relative to shutting down engines or not.
What will/does the cue card indicate for this?
From the viewpoint of a control system, how much time is there from a valid indication
during flight of an ECO sensor switching state and the crew having to take action (flip
a switch or whatever) in an irrevocable manner - shutdown one or more engines? What is
the round trip time delay for comm -- each viable path (ground tracking station vs TDRSS)
and for commanding from Mission Control? (Any satellite links? Any delays from capcom
to and from the "back rooms"?)
Now for a few thoughts of "deja vu all over again" (apparently a Yogi Berra-ism):
The SRB O-ring seals repeatedly had problems (or was that normal behavior, based
on the analysis in that time frame?). A condition that was outside the then current
flight experience (cold weather) plus, perhaps, the need for (or could that part
be omitted) a significant wind shear on ascent led to the Rogers Commission. (Richard
Feynman certainly issued an "interesting" minority report as an appendix.)
The foam falling off the shuttle was downgraded to nothing more than a source of
maintenance work. It seems that an out-of-family piece of that same foam lead to
the CAIB.
Speaking of the CAIB, some interesting comments relating to power point presentation
were made that were not particularly complimentary when the objective is to get to
the bottom of things -- hmmm, an inadvertent pun considering where some of the ECO
sensors are located. Why mention that here? Perhaps with L2 (which I do not have),
my viewpoint would be different. However, based on what information I do have,
this current situation is too reminiscent of the situation that led to CAIB and
to the Rogers Commission. (Management hat vs Engineering hat -- anybody mind if
I wear a helmet instead?)
If the new "instrumentation on instrumentation" is providing sufficiently timely and
accurate information, take the time to "hardwire" it or "firmly" patch it into the
onboard software so that the crew can take appropriate action. Forget about
the schedule. A recent action, referred to as good news on this site, seems to indicate
that flight past the Sept 30, 2010, date is plausible. It is hard to believe that if
a good-faith effort to meet that date were to still result in a 1 or 2 month slippage past it
(which would also mean that the current 6 month or so pad following March, 2010, would have
also have been used), that the Congress would not provide a one-time incremental funding
On the other hand, was it Gen. Eisenhower that said he would rather have someone under his command
that was lucky than good? Thinking that through, hopefully, at a minimum, good luck rides with the crew
and preferrably both good luck and good decisions whenever the actual launch occurs.
------------------------------------------------------------------------------------------------------------------------------
Enough lost sleep for me -- back to sleep for a few hours.
Just my thoughts.
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Errr... as I'm not that goot at statistics I have a rather simple question:
where has the countdown clock in NASA-Web 5.0 gone??
I miss it!
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lsullivan411 - 9/12/2007 2:50 AM
Looks like maybe a damaged Tyvek cover, or is this just shadow?
Looks like its little 'parachute' may be flapping in the breeze a bit.
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Wisi - 9/12/2007 3:27 AM
Errr... as I'm not that goot at statistics I have a rather simple question:
where has the countdown clock in NASA-Web 5.0 gone??
I miss it!
This one?
http://countdown.ksc.nasa.gov/shuttle/countdown/cdt/
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MKremer - 9/12/2007 10:33 AM
Wisi - 9/12/2007 3:27 AM
Errr... as I'm not that goot at statistics I have a rather simple question:
where has the countdown clock in NASA-Web 5.0 gone??
I miss it!
This one?
http://countdown.ksc.nasa.gov/shuttle/countdown/cdt/
No, the small Flash-Clock that could be found via the Shuttle-Main-Page on the old NASA-Website. But this one works to. Is it up to date? As per http://spaceflightnow.com/shuttle/sts122/status.html we should be already in the T-6 hours hold... but the clock shows T-6hrs 17mins
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MKremer - 9/12/2007 4:31 AM
lsullivan411 - 9/12/2007 2:50 AM
Looks like maybe a damaged Tyvek cover, or is this just shadow?
Looks like its little 'parachute' may be flapping in the breeze a bit.
Thanks - was watching a little longer and starting to think that's what it might be.
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Wisi - 9/12/2007 1:27 AM Errr... as I'm not that goot at statistics I have a rather simple question: where has the countdown clock in NASA-Web 5.0 gone?? I miss it!
The webmaster for NASA.gov probably has little confidence that Atlantis will launch today that he/she didn't feel like updating the countdown clock on the page :bleh:
PS: The Tyvek covers on the shuttle look fine.
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One hour til tanking begins.
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Go for tanking expected soon.
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15 minutes to tanking, which will begin with chilldown, then slow fill.
Fast fill follows, and then we'll start to be in the area of watching the ECO readings.
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About an hour before the first SIM command which is when the ECO readings went bad last time out.
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Is nasa tv coverage still scheduled to start at 6:00?
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dember - 9/12/2007 10:49 AM
Is nasa tv coverage still scheduled to start at 6:00?
Probably.
Remember everyone, this is a live update thread. No posts unless it is an update on status.
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dember - 9/12/2007 5:49 AM
Is nasa tv coverage still scheduled to start at 6:00?
Yes, since essentially nothing has changed.
If there's a schedule, it's only likely to be pre-empted by a change. If a TV event says "no earlier than," that means they aren't sure when it's going to start.
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Chilldown begining, following go for tanking.
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NASA TV switched to KSC graphics...
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Initial PAO statement (George Diller) -- as already noted, go for tanking at 5:56 am. Chilldown started at 5:58 am.
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Expect to see first SIM test on the ECOs in about 40 minutes...around 6:35 am Eastern.
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I thought I was going mad when there wasn't a sign of go for tanking with five minutes to go :)
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Chris Bergin - 9/12/2007 6:02 AM
I thought I was going mad when there wasn't a sign of go for tanking with five minutes to go :)
If it's good news we might hear it near real-time, but I still think you will hear about the SIM test results before it gets to NASA TV.
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George Diller back to say that liquid hydrogen is now in slow-fill.
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And now slow-fill has started on the liquid oxygen side.
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9 hours exactly until launch...
(according to NASA.gov's countdown clock)
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We could do a caption competition with this (but we won't!! - live update thread) ;)
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George Diller back with a quick update...still in slow-fill on both LH2 and LO2...things still going smoothly all-around.
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20% concern with weather currently...
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So far so good. All four LH2 ECOs went wet (per L2).
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First indication now that the LH2 low-level/ECO sensors are becoming wet, per PAO.
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ntschke - 9/12/2007 6:29 AM
Come on ECOs!
The "favorable" scenario means that we will be watching a pot boil, so to speak -- all morning and most of the afternoon. They have to behave all the way down to the last GLS milestone at T-31 seconds (if not to T-0).
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When will the first SIM DRY-commands be sent?
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kimmern123 - 9/12/2007 6:31 AM
When will the first SIM DRY-commands be sent?
PAO indicated around 6:35 am, but that's a gross estimate.
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Please remember, this is a live update thread. NO posts unless they are specific updates. The reason people will be catching up during the day and don't need to trawl through lots of posts of "great news!" etc. Use the cheerleading thread. I'm here with you thinking the same, but we need stop it from turning into 60 pages of "woo hooing" ;)
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George Diller says slow-fill still in effect...the 5% sensor isn't completely wet yet.
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Daybreak at the cape:
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LO2 has transitioned to fast fill.
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PAO says to expect to know about how things are going on the LH2 side in the next half hour.
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About 10-15 mins from the first SIM test (command sent to turn ECOs from WET to DRY and back again) I believe.
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LH2 5% sensors are wet and transitioning to fast fill.
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No issues with the ECOs so far.
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PAO: LH2 ECO sensors have "cycled" and all are currently working.
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Sensor #3 has failed.
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PAO: LH2 console reports that one of the LH2 ECO sensors (#3) has failed (presumably "WET").
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Crap :( Will get details on the exact problem.
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'LH2 #3 ECO sensor has failed WET. This is NOT good news...'
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As per L2, it's an open circuit again.
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Per yesterdays discussion this MUST result in a scrub today right?
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triddirt - 9/12/2007 6:54 AM
Per yesterdays discussion this MUST result in a scrub today right?
Yes -- they said that in this case, they'd have a lot of troubleshooting to do, today and in the days ahead.
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According to yesterday's LCC update this is a scrub and essentially now becomes a tanking test.
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psloss - 9/12/2007 6:54 AM
triddirt - 9/12/2007 6:54 AM
Per yesterdays discussion this MUST result in a scrub today right?
Yes -- they said that in this case, they'd have a lot of troubleshooting to do, today and in the days ahead.
OK.. I hope they pre-packed Dan Tani a Christmas stocking... He may need it.
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prepare for scrub call.
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triddirt - 9/12/2007 6:56 AM
OK.. I hope they pre-packed Dan Tani a Christmas stocking... He may need it.
Delays in general are always a possibility.
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official scrub
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George Diller back...they will continue filling for the next half-hour to facilitate troubleshooting.
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This stinks! :(
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Interesting that it was only ECO #3 and not 3 AND 4 as was the case on Thursday. Per the previous flight rules, 3 of 4 would have been acceptable. Now we're looking at a possible January launch if they can't figure it out at the pad. Damn.
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Well, looking at this from the half-full side, this is new data (well, a new pattern) and may help them get to a root cause.
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Worth mentioning to L2 users, but the plans for this are available with the repair timeline graphs and what they'll now get out of a tanking test.
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Plan is to stop filling after 30 minutes, see if any more data needs to be collected. If not, they will drain at that point.
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PAO says an official scrub hasn't been called, but it's somewhat academic.
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NO official scrub announced yet - per PAO
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MMT is meeting to discuss the situation.
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Does this mean MMT will discuss the option of continuing the countdown with 3/4 sensors?
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Wayne sounded pretty firm. I don't think he'll let this one slide.
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Maybe still a small chance the MMT will not scrub?
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MMT has asked propulsion to come up with a timeline on how long it would take to drain LOX and LH2 to 5%. Will be a MMT meeting shortly to discuss what the official status will be. They have not declared an official scrub, but the LCC will not allow them to continue in this formation.
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ntschke - 9/12/2007 12:00 PM
Interesting that it was only ECO #3 and not 3 AND 4 as was the case on Thursday. Per the previous flight rules, 3 of 4 would have been acceptable. Now we're looking at a possible January launch if they can't figure it out at the pad. Damn.
seems less likely to be wiring that's common to both sensors then. perhaps it is actually a fault with the sensors, rather than wiring or connectors.
a pity they can't launch with only the one failure. but if one sensor "fixed" itself today, then maybe tomorrow the other one will be fixed too. fingers crossed.
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Was/is there an option of draining, collecting data, and refilling and still make the window? (Assuming of course that all sensors function on the refill)
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ntschke - 9/12/2007 12:10 PM
Was/is there an option of draining, collecting data, and refilling and still make the window?
Is that what the PAO was just hinting at?
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Bruce - 9/12/2007 7:09 AM
a pity they can't launch with only the one failure. but if one sensor "fixed" itself today, then maybe tomorrow the other one will be fixed too. fingers crossed.
It could argued the other way, though, too: this situation is different than other launch campaigns and the data is telling them to stop and look deeper.
Which is why it's nearly pointless to speculate -- we don't have sufficient insight on the outside to make those conclusions in real-time.
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Gonna get pretty busy in the firing room right now.
'This could be a good thing, because we will get data from the launch attempt, and from the test this morning, which might help us find the root cause.'
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No official scrub yet, but LCC rules are LCC rules and this configuration denotes scrub.
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Will continue filling the tank for another 15 minutes.
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Wayne Hail and Leroy Cain having an 'across-the-console huddle' to figure out the gameplan.
Mike Leinbach has now entered the 'huddle'.
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Chris Bergin - 9/12/2007 7:11 AM
No official scrub yet, but LCC rules are LCC rules and this configuration denotes scrub.
At least today's LCC rules around ECO sensors... Bet the rules CONTINUE to get revisted during this week..
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Now Mike Leinbach has joined the group at the Launch Director console. What's supposed to be his role today?
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triddirt - 9/12/2007 7:14 AM
At least today's LCC rules around ECO sensors... Bet the rules CONTINUE to get revisted during this week..
That's largely dependent on how smart the program gets on this UA in the near future.
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Diller is earsdropping on the flight directors :)
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triddirt - 9/12/2007 12:14 PM
Chris Bergin - 9/12/2007 7:11 AM
No official scrub yet, but LCC rules are LCC rules and this configuration denotes scrub.
At least today's LCC rules around ECO sensors... Bet the rules CONTINUE to get revisted during this week..
Yeah. They've got that "interesting data point" of this being the one sensor (ECO LH2 3) and not (4). Will be interesting (and we're watching) as remember, (1) failed during detank last time out.
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But the launch rule wasn't that they CAN go fly with 3 sensors operating properly ?
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Currently fine-tuning the troubleshooting plan.
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MMT now convening on a single channel for discussions. Should have results soon?
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The timing and pattern of how the circuits signal during drain is also something to be compared to the first tanking. (i.e., when they go back to DRY) And drain also simulates in-flight...
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ksc_houston - 9/12/2007 7:18 AM
But the launch rule wasn't that they CAN go fly with 3 sensors operating properly ?
For today, the rule was 4 of 4.
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Scrub anyway due to "30 minute timer" when entering fast fill. (per L2) Though that's the first time I've heard of this "timer".
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Kind of wish they wouldn't of changed the LCC.
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Direction to the launch team is 'continue, do not change any procedures until told to do so'.
EDIT: They changed the LCC so it'd be 4/4 for today, right? Couldn't they just change it again for 3/4? :o
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Earlier it was mentioned that they may drain back down to 5% and try filling again. Could this possibly be done and still be successful today in time for a possible launch?
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Not today. I don't think so.
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dember - 9/12/2007 12:22 PM
Kind of wish they wouldn't of changed the LCC.
Might not of passed through the MMT though. Remember, JSC Engineering, ET Project and SE&I (I believe) were...I won't say dissent, but had "questions" and the 4/4 may of been a wish. Crap wording on my part, but you get the idea.
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Confirmation of a scrub. Coming from Leroy Cain and Doug Lyons.
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shuttlefan - 9/12/2007 12:23 PM
Earlier it was mentioned that they may drain back down to 5% and try filling again. Could this possibly be done and still be successful today in time for a possible launch?
Nope.
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shuttlefan - 9/12/2007 7:23 AM
Earlier it was mentioned that they may drain back down to 5% and try filling again. Could this possibly be done and still be successful today in time for a possible launch?
Even if they tried filling again, it would be for troubleshooting.
I know there's some anxiousness out there for a launch, but if you follow the shuttle program, you will learn to be patient.
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That's it. Scrubbed. Now we see what they can find from the troubleshooting.
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OFFICIALLY SCRUBBED!
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official scrub from PAO
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GO to begin draining LO2.
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When is the earliest we could try again?
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dember - 9/12/2007 7:27 AM
When is the earliest we could try again?
That depends on MMT. If they find something, then it could be weeks. It all depends on the data..
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dember - 9/12/2007 7:27 AM
When is the earliest we could try again?
Way too early to know that with any reasonable certainty.
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dember - 9/12/2007 12:27 PM
When is the earliest we could try again?
To be honest, I think this is now going to be January, as per troubleshooting notes. We'll see what the MMT decide. Too early to say yet. They could even try again tomorrow...we'll see.
Remember, we're also watching the sensors still. They will go through some more tests.
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Watching the LH2 ECO sensor, waiting to see if/when it clears.
Hoping to get someone from senior management to talk with PAO, but they are extremely busy right now.
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Chris Bergin - 9/12/2007 7:28 AM
To be honest, I think this is now going to be January, as per troubleshooting notes. We'll see what the MMT decide. Too early to say yet.
Yup. At this point, they are probably several steps away from being able to talk about a new launch date. It's mostly dependent on a lot of troubleshooting (hinted at last night by Doug Lyons that they'd start after detanking with going into the aft).
They have to collect data, analyze it, and discuss what to do. And then possibly repeat that sequence.
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Chris Bergin - 9/12/2007 12:28 PM
dember - 9/12/2007 12:27 PM
When is the earliest we could try again?
To be honest, I think this is now going to be January, as per troubleshooting notes. We'll see what the MMT decide. Too early to say yet. They could even try again tomorrow...we'll see.
Remember, we're also watching the sensors still. They will go through some more tests.
January won't have that bigger impact on the schedule as if all goes to plan we could get 6 in 2008 or 5 in 2008 and then 5 in 2009, so I think we're pretty flexible at the moment...
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Ford Mustang - 9/12/2007 7:27 AM
dember - 9/12/2007 7:27 AM
When is the earliest we could try again?
That depends on MMT. If they find something, then it could be weeks. It all depends on the data..
If they attempt on Monday and fail to launch, then must standdown for 48 hours to replenish Orbiter cryogenics (fuel cell fuel). This means NET Thursday.. This is per Leinbach on Saturdays Post MMT conference
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Have there been concerns in the past about how all the tanking and detanking may affect the integrity of the ET foam?
I seem to remember a change was made to the recently around how long the stack was on the ground after the ET being filled? Not sure exactly...
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Stopped flow on LO2, for preparations with draining LO2.
Countdown clock will continue to count backwards, but they have scrubbed.
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triddirt - 9/12/2007 7:32 AM
If they attempt on Monday and fail to launch, then must standdown for 48 hours to replenish Orbiter cryogenics (fuel cell fuel). This means NET Thursday.. This is per Leinbach on Saturdays Post MMT conference
Very unlikely to attempt on Monday -- that would have been for something like KSC weather. They have an unexplained problem and new circumstance; can't just recycle.
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LO2 detanking has commenced. Will be a few minutes until they see indications of it on their screens, but it has started, nonetheless.
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I'm going to be a Gloomy Gus and predict this will end up being a rollback, and launch maybe even a week or two later than the Jan. 2nd date mentioned.
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jaredgalen - 9/12/2007 7:33 AM Have there been concerns in the past about how all the tanking and detanking may affect the integrity of the ET foam? I seem to remember a change was made to the recently around how long the stack was on the ground after the ET being filled? Not sure exactly...
It was mentioned in yesterday's post MMT that the tank is capable of 13 cycles. I believe that means a fill and drain is 2 cycles (can anyone confirm that for me?)
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My money is on a Mid-January time frame.
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We'll go when we get things right. That's as it should be.
Roci
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ShuttleDiscovery - 9/12/2007 12:32 PM
Chris Bergin - 9/12/2007 12:28 PM
dember - 9/12/2007 12:27 PM
When is the earliest we could try again?
To be honest, I think this is now going to be January, as per troubleshooting notes. We'll see what the MMT decide. Too early to say yet. They could even try again tomorrow...we'll see.
Remember, we're also watching the sensors still. They will go through some more tests.
January won't have that bigger impact on the schedule as if all goes to plan we could get 6 in 2008 or 5 in 2008 and then 5 in 2009, so I think we're pretty flexible at the moment...
Correct. To add, if they launch by mid Jan, they can still get 123 off in Feb. The constraint is getting all their reviews from the 122 mission looked at. They were still coming in for STS-120, a few weeks before the opening launch date for STS-122.
Also, the LON timeline needs to be considered, but the flows are green.
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MKremer - 9/12/2007 6:34 AM
I'm going to be a Gloomy Gus and predict this will end up being a rollback, and launch maybe even a week or two later than the Jan. 2nd date mentioned.
I'm with you, "Gloomy Gus"!! ;)
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MKremer - 9/12/2007 7:34 AM
I'm going to be a Gloomy Gus and predict this will end up being a rollback, and launch maybe even a week or two later than the Jan. 2nd date mentioned.
It will be interesting to see if they really go all out to find root cause or if they could go into another tanking down the road with this unexplained. It's like the question at the presser last night -- "are we going to be wondering about ECO sensors for the rest of the program?"
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The basis for the launch attempt today was this has happened before and on the second fill, the issue corrected itself. If 4/4 worked, then the issue would have been in the family of those previous problems and they were more comfortable launching. This is the first time they have re-filled the tank and not had a sensor work.
Based on that, this is out-of-family and it becomes more difficult to justify "try again and see if it works" without more data. With that in mind, it makes an attempt in the next day or two unlikely unless the troubleshooting points to something that's quick to fix
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ntschke - 9/12/2007 6:35 AM
jaredgalen - 9/12/2007 7:33 AM Have there been concerns in the past about how all the tanking and detanking may affect the integrity of the ET foam? I seem to remember a change was made to the recently around how long the stack was on the ground after the ET being filled? Not sure exactly...
It was mentioned in yesterday's post MMT that the tank is capable of 13 cycles. I believe that means a fill and drain is 2 cycles (can anyone confirm that for me?)
The tank hardware is good for 13 cycles. Wayne also mentioned they still may need to repair cracks or other foam problems that can develop well before that, though.
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Mike_1179 - 9/12/2007 6:37 AM
The basis for the launch attempt today was this has happened before and on the second fill, the issue corrected itself. If 4/4 worked, then the issue would have been in the family of those previous problems and they were more comfortable launching. This is the first time they have re-filled the tank and not had a sensor work.
Based on that, this is out-of-family and it becomes more difficult to justify "try again and see if it works" without more data. With that in mind, it makes an attempt in the next day or two unlikely unless the troubleshooting points to something that's quick to fix
Did they not have trouble with the ECOs on both STS-114 tanking tests though?
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Chris Bergin - 9/12/2007 7:37 AM
Also, the LON timeline needs to be considered, but the flows are green.
From a hardware processing standpoint, this kind of relieves time pressure on the LON...except that they may not want to stack the next ET "on-time" given the current situation...
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Confirmation that LO2 is draining.
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shuttlefan - 9/12/2007 7:38 AM
Did they not have trouble with the ECOs on both STS-114 tanking tests though?
Yes; however, they changed tanks and a lot of electronics in the orbiter aft after that. (Including the point sensor box.)
And still had one of the circuits fail WET on the first launch attempt tanking.
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How will this latest delay affect NRO L-24. If a longer delay is announced today, can the Atlas be launched tomorrow, or not?
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LOX ECO number 3 just failed DRY, per L2. Damn.
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Don't lynch me, but thats a completely separate one to the ones that failed the other time, correct?
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Chris Bergin - 9/12/2007 12:37 PM
Correct. To add, if they launch by mid Jan, they can still get 123 off in Feb. The constraint is getting all their reviews from the 122 mission looked at. They were still coming in for STS-120, a few weeks before the opening launch date for STS-122.
Also, the LON timeline needs to be considered, but the flows are green.
Leo isn't going to get very long in space! I can predict a 117/118 style crew change alreday whereby Reisman launches on 124! :o
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Gekko0481 - 9/12/2007 6:43 AM
Don't lynch me, but thats a completely separate one to the ones that failed the other time, correct?
Yes, before it was LH2 sensors, now it's a LOX sensor, which probably is going to make this situation worse. But I would wait for more from Chris before jumping to a conclusion.
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Gekko0481 - 9/12/2007 12:43 PM
Don't lynch me, but thats a completely separate one to the ones that failed the other time, correct?
To summarize:
LH2 ECO Number 3 failed WET
LOX ECO Number 3 failed DRY <--new issue.
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Chris Bergin - 9/12/2007 6:41 AM
LOX ECO number 3 just failed DRY, per L2. Damn.
Sorry if I'm jumping on this too early Chris, but is this the first case of a LOX ECO failing in the history of this whole ECO sensor fiasco?
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uko - 9/12/2007 7:17 AM
Diller is earsdropping on the flight directors :)
Flight directors are in Houston.
There is only one Launch Director, Leinbach,
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Jim - 9/12/2007 1:46 PM
uko - 9/12/2007 7:17 AM
Diller is earsdropping on the flight directors :)
Flight directors are in Houston.
There is only one Launch Director, Leinbach,
Don't forget Doug Lyons! He's the STS-122 LD.
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DaveS - 9/12/2007 6:48 AM
Jim - 9/12/2007 1:46 PM
uko - 9/12/2007 7:17 AM
Diller is earsdropping on the flight directors :)
Flight directors are in Houston.
There is only one Launch Director, Leinbach,
Don't forget Doug Lyons! He's the STS-122 LD.
And all the other launch controllers sitting at their consoles.....
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Hoping to have Doug Lyons at the console with the PAO.
MMT will formally convene in about 1 hour. We do anticipate to have a press conference whenever that is over.
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shuttlefan - 9/12/2007 6:46 AM
Chris Bergin - 9/12/2007 6:41 AM
LOX ECO number 3 just failed DRY, per L2. Damn.
Sorry if I'm jumping on this too early Chris, but is this the first case of a LOX ECO failing in the history of this whole ECO sensor fiasco?
The LOX ECOs were the problem during the earlier flights, I recall.
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Did they have ECO problems for 25 years of the program or has it gone worse in recent years?
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Videos
STS-122 - TANKING COMMENTARY Part 1
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&task=view&id=3186&Itemid=2
STS-122 - TANKING Scrubbed
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&task=view&id=3187&Itemid=2
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dotdk - 9/12/2007 6:56 AM
Did they have ECO problems for 25 years of the program or has it gone worse in recent years?
It got far more worse starting with the first tanking test for the Return-to-Flight mission, STS-114 in 2005.
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Andy USA - 9/12/2007 1:55 PM
shuttlefan - 9/12/2007 6:46 AM
Chris Bergin - 9/12/2007 6:41 AM
LOX ECO number 3 just failed DRY, per L2. Damn.
Sorry if I'm jumping on this too early Chris, but is this the first case of a LOX ECO failing in the history of this whole ECO sensor fiasco?
The LOX ECOs were the problem during the earlier flights, I recall.
Wrong! It has always the been the LH2(hydrogen) ECO sensors that have failed. Never a LOX ECO sensor.
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Did things just get better or worse?
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To add, they've still got LOX in the tank, they've not drained it back yet...hense "failing DRY" on that LOX ECO number 3.
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shuttlefan - 9/12/2007 6:58 AM
dotdk - 9/12/2007 6:56 AM
Did they have ECO problems for 25 years of the program or has it gone worse in recent years?
It got far more worse starting with the first tanking test for the Return-to-Flight mission, STS-114 in 2005.
That's because they changed the launch criteria.
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dember - 9/12/2007 1:59 PM
Did things just get better or worse?
Worse! Especially with a LOX ECO sensor failing "DRY".
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Still draining LOX. Once that is finished, going to drain LH2. Troubleshooting begins particularly at 5%.
EDIT: Dave, if there was LOX still in the tank, wouldn't it fail dry anyways, since it was still wet, as Chris has said?
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To address some of the recent inaccurate comments:
- This is the first LOX ECO failure.
- This is the first "Failed Dry" failure
- The LCC changed post-Challenger from 3/4 to 4/4. The LCC didn't change RTF on the count (I cannot say for sure whether the number of times they're looked at during the countdown changed RTF).
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Ford Mustang - 9/12/2007 1:01 PM
Still draining LOX. Once that is finished, going to drain LH2. Troubleshooting begins particularly at 5%.
EDIT: Dave, if there was LOX still in the tank, wouldn't it fail dry anyways, since it was still wet, as Chris has said?
Eh? The sensor should show "WET" as it is wet with LOX. To show DRY is an error.
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Chris Bergin - 9/12/2007 8:05 AM
Ford Mustang - 9/12/2007 1:01 PM
Still draining LOX. Once that is finished, going to drain LH2. Troubleshooting begins particularly at 5%.
EDIT: Dave, if there was LOX still in the tank, wouldn't it fail dry anyways, since it was still wet, as Chris has said?
Eh? The sensor should show "WET" as it is wet with LOX. To show DRY is an error.
Ah, misunderstood there. Thanks for clearing that up for me, Chris. Too early for all of this.. :)
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So a LOX failing dry is an open or closed circuit?
EDIT: or: if you cut the wires, an LH2 fails wet and a LOX fails dry?
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say again when this launch window closes and why
thanks
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Integrator - 9/12/2007 1:07 PM
say again when this launch window closes and why
thanks
13th - Beta Angle.
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Ford Mustang - 9/12/2007 7:01 AM
Still draining LOX. Once that is finished, going to drain LH2. Troubleshooting begins particularly at 5%.
EDIT: Dave, if there was LOX still in the tank, wouldn't it fail dry anyways, since it was still wet, as Chris has said?
So for troubleshooting to begin at 5%, will they leave 5% LH2 in the tank for awhile to perform that troubleshooting?
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joncz - 9/12/2007 8:05 AM To address some of the recent inaccurate comments: - This is the first LOX ECO failure. - This is the first "Failed Dry" failure - The LCC changed post-Challenger from 3/4 to 4/4. The LCC didn't change RTF on the count (I cannot say for sure whether the number of times they're looked at during the countdown changed RTF).
Up until yesterday, the LCC was 3/4. They switched to 4/4 for this attempt only. Was it ever 4/4 beofore today?
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and the next opportunity is Jan 9? we have requested special instrumentation on the next flight so this will affect that request.
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About 15 minutes left with draining of LOX. At that point, they may sit for a few minutes on the LH2 (and not drain right away).
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How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
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Anyone think we can get off before the 13th? I'm doubtful.
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Prior to Challenger it was 3/4. Post-Challenger they went to 4/4 until they started having ECO problems. Then they revisited the requirement and went back to 3/4.
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dabella - 9/12/2007 2:11 PM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
That is what they don't know! Could be wiring, could be the sensors. They don't know.
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dabella - 9/12/2007 7:11 AM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
Dan.-
The work itself isn't particularly difficult but it would result in a long delay as they'd have to rollback to the Vehicle Assembly Building to actually do the work... The work is complex though because the technicians would have to enter a manhole at the bottom of the tank and then climb up into the tank to reach the sensors. Maybe I shouldn't be saying it isn't difficult but they've replaced those sensors before.
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dabella - 9/12/2007 8:11 AM
How difficult is to replace the failing ECO's? If the problem are the sensors itself that should fix it?
That's the thing -- the history of this says that the sensors themselves aren't necessarily suspect. They've never been able to isolate a location within the whole circuit from the sensor in the tank to the electronics box that processes the signal inside the orbiter aft compartment.
They replaced the LH2 sensors on the STS-115 tank, and one of the circuits STILL failed wet on the 1st tanking.
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Doug Lyons now talking to PAO. I'm recording this.
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All 4 sensors went DRY by SIM command, for about two or three minutes. Then #3 failed, and went back to WET.
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PAO: Where do you think we go after today?
Lyons: MMT meeting at 9 AM, trying to decide where to go. Multiple paths going into MMT, will try to decide which way to go, to implement as soon as possible.
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Coverage ended
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Sounds like they'll hold at 5% in the LH2 tank for about 4 hours to troubleshoot, did I pick that up correctly?
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Well, if this is a complex problem that is repeating over time and is a security issue and the root cause is unknown, imho, its a good idea to pause the program until a fix or a replacement to the system is found...
it will take time, but its the safest way to go i think..
Dan.-
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Sounds like they'll have to throw the full resources of NASA at this one.
They can't have this little niggly problem plagueing the rest of the remaining flights.
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Do yall think the MMT will decide to roll her back and fix the problem?
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Engineers checking the status of the LOX ECO Number 3 issue, regarding if it's a SIM failure (bad) or a "PSB dry transition range" <--not sure if that's still as bad, but they are looking at it. Hopefully it's not a straight out fail, but I don't know more than what I'm getting.
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dabella - 9/12/2007 8:25 AM
Well, if this is a complex problem that is repeating over time and is a security issue and the root cause is unknown, imho, its a good idea to pause the program until a fix or a replacement to the system is found...
The failures in the past have only occurred during a full tanking and even then have been intermittent. So in the past they have been unable to reproduce the problem. This is the first time a sensor circuit has failed WET on successive tanking cycles. And how it behaves during detanking today is TBD. (The "detankings" in the past "second tankings" have been "flight drains" and I believe the circuits continued to behave as predicted in-flight.)
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Justin Wheat - 9/12/2007 1:28 PM
Do yall think the MMT will decide to roll her back and fix the problem?
We do not know at this stage. Let's please keep the chatter down to a minimum, as we're trying to provide live updates.
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If they roll back for repairs which High Bay will the stack end up in?
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ETEE - 9/12/2007 8:33 AM
If they roll back for repairs which High Bay will the stack end up in?
Whichever integration cell is open.
Edit -- the 123 boosters are being stacked in HB 1, so that would be HB 3.
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Well, this is a 'surprise'...
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Ford Mustang - 9/12/2007 8:36 AM
Well, this is a 'surprise'...
Not to this geek...seen it before. :)
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It's probably already been asked, but why can't they just increase the number of sensors?
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video
STS-122 - Atlantis Status Update December 9
http://www.space-multimedia.nl.eu.org/index.php?option=com_content&task=view&id=3188&Itemid=2
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GW_Simulations - 9/12/2007 8:42 AM
It's probably already been asked, but why can't they just increase the number of sensors?
Even if they could do so hypothetically, it doesn't solve the problem. The system already has a lot of redundancy and any circuits you add could behave just like the #3 one is currently or like the #4 did on Thursday.
It would also increase overall complexity and add additional failure modes.
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GW_Simulations - 9/12/2007 7:42 AM
It's probably already been asked, but why can't they just increase the number of sensors?
The whole orbiter hw & sw system is only designed for 4.
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dabella - 9/12/2007 8:25 AM
Well, if this is a complex problem that is repeating over time and is a security issue and the root cause is unknown, imho, its a good idea to pause the program until a fix or a replacement to the system is found...
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Security issue?
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does anyone know why the ECO sensor always get into trouble?
It seems that the same problem strike many shuttle launches
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8900 - 9/12/2007 8:59 AM
does anyone know why the ECO sensor always get into trouble?
It seems that the same problem strike many shuttle launches
Incorrect -- they don't always get into trouble and it hasn't been many. This is only the fourth stack with "trouble."
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Looks like better news on the LOX ECO 3 issue. It's been classed as a possible independent SIM command console issue and not a sensor fault. (i.e. KSC sent the command, without telling the other centers, so some consoles flash it as an issue, when it was commanded to go DRY, rather than failing DRY).
They are evaluating what happened, but that is more hopeful! :cool:
Of course, that doesn't change the LH2 ECO issue.
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MMT did start at 9am per ISS comms, 24-hr turnaround is the current posture but "will know more in an hour or two"
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Are we saying there is a chance for tommorow?
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psloss - 9/12/2007 9:03 AM 8900 - 9/12/2007 8:59 AM does anyone know why the ECO sensor always get into trouble? It seems that the same problem strike many shuttle launches
Incorrect -- they don't always get into trouble and it hasn't been many. This is only the fourth stack with "trouble."
And I belive these issues have all come AFTER RTF. I'm sure they've looked into it but there must be some significance to that. Either the tanks/sensors reached a threshold of viability or...maybe there were some design change made?
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psloss - 9/12/2007 9:03 AM
8900 - 9/12/2007 8:59 AM
does anyone know why the ECO sensor always get into trouble?
It seems that the same problem strike many shuttle launches
Incorrect -- they don't always get into trouble and it hasn't been many. This is only the fourth stack with "trouble."
I'm still betting that this is a wiring issue related to the RTF mods on the ET.
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ntschke - 9/12/2007 9:07 AM
And I belive these issues have all come AFTER RTF. I'm sure they've looked into it but there must be some significance to that. Either the tanks/sensors reached a threshold of viability or...maybe there were some design change made?
No idea -- that's what they've been trying to answer since April, 2005.
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Yeah I thought it was something to do with the post-Columbia mods too as this hasn't really been an issue before...
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Officially announced at KSC press site: NET January 2.
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collectSPACE - 9/12/2007 2:16 PM
Officially announced at KSC press site: NET January 2.
Thanks Robert, so that'll currently point towards a plan of troubleshooting at the pad, for now.
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Excuse my lack of understanding but what does NET mean?
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Reno - 9/12/2007 2:25 PM
Excuse my lack of understanding but what does NET mean?
"No Earlier Than" - as in the earliest they could launch is the NET date, though it can move later as they proceed.
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This launch date protects STS-123 quite well then providing they don't rollback and delay further...
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On the ISS Audio Feed, they were talking about some concerns about EVAs and the possibility of a Stage EVA. Mission Management Team is apparently talking to Holly Ridings about this right now or very soon.
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Hi Guys,
Great site. Been a slient observer till now.
Will this have a definate knock-on effect to STS-123 & STS-124 dates or could they still be fluid? Have planned a visit in April for STS-124 but not so confident now.
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Abbotsman - 9/12/2007 8:33 AM
Hi Guys,
Great site. Been a slient observer till now.
Will this have a definate knock-on effect to STS-123 & STS-124 dates or could they still be fluid? Have planned a visit in April for STS-124 but not so confident now.
Welcome.
They are ok on the manifest until STS-122 breaches past the middle of January. Otherwise they can still launch STS-123 in February, should STS-122 launch early in January.
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GOX Vent Hood is retracted.
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Post MMT briefing posted on NASA TV for 10 am Eastern...
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Briefing is starting.
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Bill Gerstenmeier, Leroy Cain, and Doug Lyons are the briefers.
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Short term KSC troubleshooting team will report to the PRCB on Tuesday (for 1st time).
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Early January target date is preliminary; depends on what they find out based on executing the troubleshooting plan (which is TBD).
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Should finish the troubleshooting with the cryos in the LH2 tank in the early afternoon local time and then finish draining.
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The balance of the questions so far are asking for speculation...
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Will pushing back STS-122 to NET Jan affect STS-125 in August (or too early to tell)?
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Kel - 9/12/2007 3:22 PM
Will pushing back STS-122 to NET Jan affect STS-125 in August (or too early to tell)?
Not if they launch early Jan.
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The chaps said if they do get a launch in early january on 122 they wont push back any other flights.
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Sounds like conflicting views on whether or not they can pull a sensor out at the pad. Doug says it been done but...
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Reno - 9/12/2007 3:28 PM
Sounds like conflicting views on whether or not they can pull a sensor out at the pad. Doug says it been done but...
For what it's worth, the Lockheed/MAF guys preference the clean room deal (the tent we saw on the previous R&R) in the VAB....but it's not likely to be the sensors themselves.
We've got a lot of documentation on L2 in regards to the feedthrough connectors (as highlighted in documents the other day). So I'll write up what they've got on that over the next 12-24 hours as an article.
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The only thing that seemed like news out of this to me was there being some increased chance of another tanking test. Leroy Cain prefaced that by saying he was speculating to some extent and the plan would come from the troubleshooting team be presented to the program on Tuesday.
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Now, the entire GOX Vent Arm is retracted.
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Statement by the STS-122 crew:
We want to thank everyone who worked so hard to get us into space this launch window. We had support teams working around the clock at KSC, JSC, and numerous sites in Europe. We were ready to fly, but understand that these types of technical challenges are part of the space program. We hope everyone gets some well-deserved rest, and we will be back to try again when the vehicle is ready to fly.
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If they're considering putting a Time Domain Reflectometer in the circuit as part of their additional instrumentation, then they would go for another tanking test in hopes (as Leroy said) that the open circuit reoccurs. The TDR would tell them where the open circuit was.
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A lot of the focus of the investigations so far seems to have been on the possible effects of the LH2 and the cryogenic temperatures on the sensors and wiring. Is it possible that it's not that at all and that it is a mechanical problem that arises when you put tonnes of propellant in the tank? That could explain why they haven't been able to reproduce it anywhere else than with the complete stack at the pad. I wonder if that's the thinking behind detanking to the 5% level and waiting for a few hours - the sensors will still be covered but the weight of the tank will be less than the weight at the point that the problem occurred.
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Thanks for the thread to catch up with what happened :(
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As we are now holding until Jan 08, will the stack be rolled back to the VAB?
If not - will any adverse weather affect the orbiter / ET / SRBs?
I assume if the stack stays the RSS will be rolled back for protection?
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LSainsbury - 9/12/2007 1:04 PM
As we are now holding until Jan 08,
Jan. 2nd ;)
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apollo13 - 9/12/2007 5:05 PM
LSainsbury - 9/12/2007 1:04 PM
As we are now holding until Jan 08,
Jan. 2nd ;)
Yes - I know - I meant Jan 2008!!
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LSainsbury - 9/12/2007 12:04 PM
As we are now holding until Jan 08, will the stack be rolled back to the VAB?
If not - will any adverse weather affect the orbiter / ET / SRBs?
I assume if the stack stays the RSS will be rolled back for protection?
It is helpful to read back through the thread, because all of the questions have already been answered.
The new launch date is NET Jan. 2. It is not known yet if they will have to roll back. To early to tell. We will know more on Tuesday when a troubleshooting team meets with the PRCB. Also, yes the RSS should be moved back into the mate position later today.
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So if they roll back will they just pull Atlantis and put her on a new stack? or try to replace the ECOs? At this point I would want a new tank altogether, just from the "this thing is jinxed" pov.
From my POV it would be quicker to just swap the ship out to another stack (if one is ready) than to have to root around inside the tank to get the ECOs and change them.
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OK - will re-read the thread - thanks for that! :)
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Zoomer30 - 9/12/2007 12:20 PM
So if they roll back will they just pull Atlantis and put her on a new stack? or try to replace the ECOs? At this point I would want a new tank altogether, just from the "this thing is jinxed" pov.
From my POV it would be quicker to just swap the ship out to another stack (if one is ready) than to have to root around inside the tank to get the ECOs and change them.
They will have to troubleshoot everything first. It would be bad to move Atlantis to a new stack and then it turns out the problem isn't even on the ET side, but in the Orbiter's wiring. Then they would be having the same problem and would have gotten anywhere. I am sure we will know a little more on Tuesday. I am pretty confident that the folks down there at KSC will be working hard in the next few days to figure this problem out.
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Do they have a breakdown of ECO issues per shuttle? I mean does it seem like its just one ship or is it just random? I dont know. There really needs to be a way to test these things before they waste cash putting the propellants in only to find out they dont work. I would say at this point since the issue was not the same this time (different sensors) it could be a wiring issue. Broken sensors dont fix themselves.
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Very saddening to see such a perfect lead up effort get trounced by a flawed system. However they did good work and I want to thank them.
Now that we have a chance to take a breath. Let me throw in my call to disable the entire ECO sensor system.
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Zoomer30 - 9/12/2007 7:20 PM
So if they roll back will they just pull Atlantis and put her on a new stack? or try to replace the ECOs? At this point I would want a new tank altogether, just from the "this thing is jinxed" pov.
From my POV it would be quicker to just swap the ship out to another stack (if one is ready) than to have to root around inside the tank to get the ECOs and change them.
Bad and uninformed POV.
They did *exactly* this with STS-114. They hauled Discovery back to the VAB, demated her from ET-120, mated her to ET-121 rolled back out to the pad, prepped for launch.
Launch day, July 13 2005:
Prior to crew ingress a ECO sensor check was made, and guess what? LH2 ECO sensor#2 failed "WET". Launch attempt scrubbed when Stephen Robinson was being strapped in.
Spent 13 days troubleshooting the problem with no success. Although they found a very small grounding imperfecting in some wiring in Discovery which they fixed, they were never able to pinpoint it as the cause.
Now STS-115 launch attempt#2, September 8 2006:
Launch was scrubbed when LH2 ECO sensor#3 failed "WET". This despite it being changed out in the VAB to prevent this from happening.
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Zoomer30 - 9/12/2007 12:43 PM
Do they have a breakdown of ECO issues per shuttle? I mean does it seem like its just one ship or is it just random? I dont know.
On L2.
There really needs to be a way to test these things before they waste cash putting the propellants in only to find out they dont work.
They "test" them all the time. The sensors behave differently at cryo temperatures so you don't really know if they work until you tank. That is the bottom line here.
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Will this delay in any way influence the ISS crew exchanges? Leo seems to get a mighty short stay if he goes up on 122 and down again on 123.
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Believe it or not, cryo liquid tanks sensors is one area that could stand some technology improvement. Another is cryo mass flow, that allows determination of what part is liquid, what part is boiling. Turbine flow meters fail in this respect. Delta IV Heavy encountered this on first launch attempt and had an early shutdown, preventing attainment of desired orbit. The problem is rocket engineers are never sure exactly how much fuel and oxidizer their systems are using in flight, so they compensate for uncertainty by overtanking propellants and depend on ground test and derived measurements, such as those from these ECO sensors to determine cutoff criteria. True mass flow through the engine is unknown. Anyone with new sensor technology ideas in these areas should promote them and the various companies that produce liquid rocket engines should investigate integrating these new technologies. It's like driving a car on a long trip with no gas gage.
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"They "test" them all the time. The sensors behave differently at cryo temperatures so you don't really know if they work until you tank. That is the bottom line here."
Why don't they test the sensors with real cryo before putting them into the ET?
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lcs - 9/12/2007 2:40 PM
Why don't they test the sensors with real cryo before putting them into the ET?
Wayne Hale said they've done that.
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kimmern123 - 9/12/2007 7:24 PM
Will this delay in any way influence the ISS crew exchanges? Leo seems to get a mighty short stay if he goes up on 122 and down again on 123.
I mentioned that way back in the thread, but no one responded. One month after so much training isn't really fair, especially as he is an ESA astronaut so he has a lower chance of flying again.
They may have Leo come down on 124, and everyone else bumped down one flight, but who knows? We'll ahve to wait and see! :)
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Zachstar - 9/12/2007 1:57 PM
Now that we have a chance to take a breath. Let me throw in my call to disable the entire ECO sensor system.
I'll pick fixing the sensor system instead. Incredibly useful for avoiding cryo pump cavitation when you run out of prop, which has happened twice.
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Integrator - 9/12/2007 12:29 PM
Believe it or not, cryo liquid tanks sensors is one area that could stand some technology improvement. Another is cryo mass flow, that allows determination of what part is liquid, what part is boiling. Turbine flow meters fail in this respect. Delta IV Heavy encountered this on first launch attempt and had an early shutdown, preventing attainment of desired orbit. The problem is rocket engineers are never sure exactly how much fuel and oxidizer their systems are using in flight, so they compensate for uncertainty by overtanking propellants and depend on ground test and derived measurements, such as those from these ECO sensors to determine cutoff criteria. True mass flow through the engine is unknown. Anyone with new sensor technology ideas in these areas should promote them and the various companies that produce liquid rocket engines should investigate integrating these new technologies. It's like driving a car on a long trip with no gas gage.
It seems to me that if you know the precise time between when the 100% sensors go dry and when the 5% sensors go dry, and the throttle command curve between those two points, that you should be able to make a mighty-accurate prediction of when the ECOs would be uncovered.
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psloss - 9/12/2007 2:45 PM
Zachstar - 9/12/2007 1:57 PM
Now that we have a chance to take a breath. Let me throw in my call to disable the entire ECO sensor system.
I'll pick fixing the sensor system instead. Incredibly useful for avoiding cryo pump cavitation when you run out of prop, which has happened twice.
and something that you can use moving forward... there are lessons to be learned here...
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Lee Jay - 9/12/2007 3:03 PM
It seems to me that if you know the precise time between when the 100% sensors go dry and when the 5% sensors go dry, and the throttle command curve between those two points, that you should be able to make a mighty-accurate prediction of when the ECOs would be uncovered.
That be one 5% sensor I think... so if its gone now what?
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Lee Jay - 9/12/2007 3:03 PM
It seems to me that if you know the precise time between when the 100% sensors go dry and when the 5% sensors go dry, and the throttle command curve between those two points, that you should be able to make a mighty-accurate prediction of when the ECOs would be uncovered.
But as we saw - engines can run richer or leaner than anticipated, or system leak can use more than anticipated...
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rdale - 9/12/2007 1:14 PM
Lee Jay - 9/12/2007 3:03 PM
It seems to me that if you know the precise time between when the 100% sensors go dry and when the 5% sensors go dry, and the throttle command curve between those two points, that you should be able to make a mighty-accurate prediction of when the ECOs would be uncovered.
But as we saw - engines can run richer or leaner than anticipated, or system leak can use more than anticipated...
Right...but tank volume change is ground truth.
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Avron - 9/12/2007 3:03 PM
and something that you can use moving forward... there are lessons to be learned here...
Well, maybe. It's a much more straightforward thing if you know what root cause is. So far, they've had a much tougher choice/risk trade without knowing root cause and they may be faced with it again.
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Maybe Congressman Weldon introduced his bill because he psychically forsaw that the sensors will require until 2015 to work properly...
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The system may be flawed and has a few sneaky gremlins, but its needed. Is it possible that testing them "dry" may damage them? If it does, it would be a nasty paradox. You need to know if they can sense a "dry" condition but in doing so they may not be able to sense a dry condition the next time. I'm thinking of heat build up.
If I read it right, when the cryo gets below the sensor level, the heat cant disapate as quick, this tells the computer that the cyro is low.
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ShuttleDiscovery - 9/12/2007 1:43 PM
kimmern123 - 9/12/2007 7:24 PM
Will this delay in any way influence the ISS crew exchanges? Leo seems to get a mighty short stay if he goes up on 122 and down again on 123.
I mentioned that way back in the thread, but no one responded. One month after so much training isn't really fair, especially as he is an ESA astronaut so he has a lower chance of flying again.
They may have Leo come down on 124, and everyone else bumped down one flight, but who knows? We'll ahve to wait and see! :)
That would mean no Americans on ISS between the next Soyuz and 124.
Won't happen.
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Jorge - 9/12/2007 8:49 PM
That would mean no Americans on ISS between the next Soyuz and 124.
Won't happen.
Or maybe not, then! :)
It would just be more hassle to swap the FE2s around anyway, I suppose. I'm sure Leo will be grateful no matter how long he gets on ISS..
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Something intresting on the KSC camera feeds. Look at channel 13 which is currently on camera 61..they have it zoomed in on the top part of the tank looking at something. It looks like there may be a crack but I really cannot tell. Maybe someone else can elaborate as to what they may be looking at?
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Zoomer30 - 9/12/2007 3:47 PM
The system may be flawed and has a few sneaky gremlins, but its needed. Is it possible that testing them "dry" may damage them? If it does, it would be a nasty paradox. You need to know if they can sense a "dry" condition but in doing so they may not be able to sense a dry condition the next time. I'm thinking of heat build up.
If I read it right, when the cryo gets below the sensor level, the heat cant disapate as quick, this tells the computer that the cyro is low.
We know its an open circuit, the question is where and why...
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hobson911 - 9/12/2007 3:25 PM
Something intresting on the KSC camera feeds. Look at channel 13 which is currently on camera 61..they have it zoomed in on the top part of the tank looking at something. It looks like there may be a crack but I really cannot tell. Maybe someone else can elaborate as to what they may be looking at?
Sure is closed in tight...
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Did a google search on something like:
eco sensor design failure space shuttle
One of the url returned was:
www.nasa.gov/pdf/160763main_NESC%20Update,%20Volume%204.pdf
[Ok, hope I cut and pasted that correctly.]
The title of the document found there is:
STS-114 Engine Cut-off Sensor Anomaly Technical Consultation Report
Lets just say that there is material there that I find appalling. If the report is accurate, and
the results are so eye-catching that some independent check needs to be done that the
report found is indeed authentic, there are, at least based on my perspective, unbelieveable
problems.
For starters, look at the possibility mentioned for noisy power supply. In that seems to be
the distinct possibility that the power supply/converter is oscillating. In addition 741 op amps
are apparently subject to overvoltage possibilites). It certainly seems that the erratic behaviour
has odds at least one to two orders of magnitude greater to be found in the point sensor box
than in the sensor or the wiring.
The apparent design flaws with the PSB are in all boxes. It is hard to believe that the wiring
and/or sensors are the culprit. Having said that, it is possible that, if the PSB design is marginal
or has negative margin (a phrase "borrowed" from a different context from the CAIB), small legitimate
wiring changes to the sensors (stray capacitance, wire inductance) could affect the operation of
the PSB.
I have heard nothing about a redesign of the PSB box since STS-114. Personally, if the report is
accurate, the design is not acceptable for non-man-rated applications, let alone a manrated one.
Just my perspective. (Reminds me of the temp sensor problems that were known prior to 51-F, but
they kept flying. It seems to be that the troubleshooting effort if barking at a shadow and not at the
root cause. Oh well, ..........
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There's lots of different rocket designs being used. OK, not many that are man-rated, but surely someone else has solved this problem of eco sensors. Is it something that can be bought elsewhere? Presumably the whole system would need to be changed, and that's not going to happen quickly.
Maybe there's more to this 2015 extension. Maybe NASA have said there's too much pressure to get ISS complete AND finish by 2010. Maybe someone has finally realised that NASA will look just a bit silly with a 5 year must-rely-on-soyuz plan.
Either design to fly safely without eco sensors. Or install a system that works. Wayne Hale's comment/excuse about them being borrowed technology from the Saturn programme is about as close to an admission of "not fit for purpose" as we'll ever get.
All IMHO of course :)
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hey you - 9/12/2007 3:08 PM
Did a google search on something like:
eco sensor design failure space shuttle
One of the url returned was:
www.nasa.gov/pdf/160763main_NESC%20Update,%20Volume%204.pdf
[Ok, hope I cut and pasted that correctly.]
I'll do the same search, but the document pulled up by your URL above includes only the following:
The NESC was part of a team to determine the root cause of the anomalous behavior
observed in the Space Shuttle Engine Cut-Off (ECO) sensor system during External
Tank (ET) tanking tests and launch attempts on STS-114. A theory was developed
that would explain how a sensor could show an apparent failure on first exposure
to liquid hydrogen (LH2), but show no indication of anomalous behavior when
returned to ambient temperature or on subsequent exposure to LH2.
The team performed cryogenic cycling of 50 fully instrumented recent vintage
(2002-2003) flight grade sensors between ambient and LH2 temperatures to determine
the validity of the theory. It was noted that the STS-114 ECO sensors
were of an earlier vintage. Both non-destructive and destructive physical analysis
techniques were employed to characterize the sensors. While all sensors behaved
nominally, nondestructive and destructive physical analysis indicated some issues
with the material selection and process variability used in the fabrication of a swaged
circuit board terminal connection that could be highly sensitive to human factors in
the assembly process and result in lot-to-lot variability.
I don't see anything particularly damning in that text...
Have a better link?
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Ok.... a couple questions that haven't been asked yet...
1. Will they offload the PRSD fuel cell load given the standown?
2. Will they execute a complete countdown backout and start a whole new countdwn from the T-43hour mark once they're back in a launch posture?
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jimvela - 9/12/2007 3:30 PM
I'll do the same search, but the document pulled up by your URL above includes only the following:
I re-ran your Google search adding one search term:
eco sensor design failure space shuttle NESC
Note the addition of NESC...
The second link down returns the following url:
http://www.nasa.gov/pdf/160734main_STS-114%20Engine%20Cut-off%20Sensor%20Anomaly%20Technical%20Consultation%20Report.pdf
This document has a great deal of analytical detail, I'll go study it. Most designs, if put under intense scrutiny yield lots of critical observations even for things with lots of flight heritage.
Maybe someone more qualified that myself will look this over and comment...
{edit to correct obvious typo}
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Trekkie07 - 9/12/2007 5:31 PM
Ok.... a couple questions that haven't been asked yet...
1. Will they offload the PRSD fuel cell load given the standown?
2. Will they execute a complete countdown backout and start a whole new countdwn from the T-43hour mark once they're back in a launch posture?
yes and yes
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jimvela - 9/12/2007 3:38 PM
This document has a great deal of analytical detail, I'll go study it.
Mods feel free to kill this post if it's excessively lengthy or off-topic...
A quick look reveals the text below. Hopefully someone else will comment further.
My reaction is that transorbs are regularly misused by EEs (I've seen this myself), but that this issue feels to me like some kind of wiring/signal path problem.
The rant I originally quoted above looks to be just that, a rant.
Just because the Transorb is rated for a higher voltage than nominal operating range of the parts in the circuit doesn't make it wrong- many circuits with high input impedances get AFU if there is enough leakage current from the transorb into the circuit. I've personally seen many more problems where a transorb value was lowered by some 'expert' causing enough leakage current to completely hose a design...
This is in my limited knowledge (no direct knowledge other than what I've read here as a non L2 member)- I shouldn't be considered an expert at anything.
Here's the FORs from that document:
http://www.nasa.gov/pdf/160734main_STS-114%20Engine%20Cut-off%20Sensor%20Anomaly%20Technical%20Consultation%20Report.pdf
8.0 Findings, Observations and Recommendations
8.1 Findings
F-1. STS-114 troubleshooting did not isolate the root cause of the ECO sensor failures.
F-2. The SSP does not test ECO sensors prior to launch countdown in LH2 at -423 deg F, but tests them in liquid nitrogen (LN2) at -320 deg F.
F-3. Isolation and continuity checks of PSB connectors are not routinely performed.
F-4. PSB transient suppressor electronics are not subjected to routine functional tests.
F-5. An Electromagnetic Interference (EMI) induced failure observed during testing of modified PSB electronics was reproduced at the NASA Shuttle Logistics Depot (NSLD). The failure was traced to circuit differences between a flight unit and the modified PSB under test, which was removed from the Shuttle Avionics Integration Laboratory (SAIL). It was initiated by non-standard sensor test resistance values and has been explained by circuit analysis and testing.
F-6. PSB electronics were subjected to stability testing in the past for several hours with no heat-sinking and no temperature monitoring. While current practice is to test the boxes on a heat-sink, latent effects of the earlier testing are unknown.
F-7. PSB electronics have been the subject of a number of workmanship issues including poor solder joints, lack of solder on some connections, and discrepant flex ribbon assemblies (the flex ribbon assemblies have been especially problematic, according to NSLD personnel). Extent of remaining workmanship problems is unknown.
8.2 Observations
O-1. While the root cause of the STS-114 failure was not identified, two probable causes surfaced including an intermittent open somewhere in the wiring from the PSB to the sensors and return, an intermittent high resistance or open of the sensor itself, or a thermally-induced intermittent failure internal to the PSB. To minimize flight risk, the SSP implemented a set of real-time screens during launch countdown to help detect and isolate a failure. The SSP determined, and the NESC concurred, that launch with a single failed ECO sensor was acceptable providing the problem could be isolated to the one sensor/electronics channel which failed during the first STS-114 launch attempt.
Sensor 2 and 4 PSB inputs were switched to facilitate real-time troubleshooting and problem isolation during launch countdown, but the failure did not recur.
O-2. There are a number of open questions pertaining to the ECO sensor. The sensors are not screened at LH2 temperatures prior to installation as noted in Finding F-1. This may affect their reliability. The design incorporates swaged terminals and stainless steel surface passivation which may also contribute to intermittent cold opens.
O-3. Since multiple power grounds enter the PSBs, they must be shown to be isolated through routine continuity and isolation tests performed at the interface connectors. The chassis continuity connections need to be verified, as do the transient suppressors installed across the sensor lines and 28-volt bus in the power converters.
O-4. Transient suppressors used in this design may be incorrectly sized. Review of the PSB power converter schematic (1500067, revision T) shows the Transient Voltage Suppressors (TVS) to be back-to-back 1N5611s. According to the data sheet for this part, it begins to zener at 43.7 volts and clamps at 63.5 volts at peak surge current. The IC1 and IC2 op-amps are 741s and are directly across the unfiltered 28-volt supply in the drawings reviewed (1500062-005 revision D). According to the data sheet, the LM741 absolute maximum Vcc rating is +22 volts, or 44 volts total. It appears that input voltage surges, particularly strong ones, may be able to overvoltage stress the op-amps if these schematics are correct.
O-5. A problem with loose card guides noted during troubleshooting of the STS-114 ECO problems has not been fully resolved. The guides in at least one PSB were re-glued (S/N 110). However, when the unit was disassembled due to a card guide lug short circuit, the guides were found to have again de-bonded. The guides are necessary to help dissipate a relatively high heat load (over 100 watts of waste heat) and are a potential source of internal contamination when de-bonded due to the potential for liberation of copper beads incorporated in the epoxy adhesive to improve thermal conductivity.
O-6. There are a number of lingering issues with parts used in the PSBs. Government-Industry Data Exchange Program (GIDEP) Alert BZ-A-80-01D covered many Fairchild Semiconductor part numbers and Lot Date Codes (LDC). Parts considered suspect during the STS-114 troubleshooting were researched (LDC 7830 2N2222), but the PSBs contain other transitors including 2N2907 and 2N2219, which may also be covered by the Alert if they were manufactured by Fairchild and are in the LDC range of concern.
O-7. Specific issues with two of the PSB’s tested during the STS-114 troubleshooting have yet to be resolved. The PSB S/N 112 power converter has been noisy. This may be related to power converter instability or limit cycle regulation. Age may affect capacitor properties that can also possibly affect stability. This should be investigated further to ensure high reliability. In addition, the potential for copper path damage between the signal conditioner card circuitry and electrical connector in PSB S/N 111 should be assessed.
O-8. Test method CS116 has replaced CS06 as a method of testing EMI / EMC compliance. Although CS116 is a less-stringent test, unlike CS06 it applies to signal lines as well as power lines. The Point Sensor Box has been designed with bandwidth-limiting networks only on the power leads. Suspicion remains that the signal lines were never designed to be subjected to high input levels and CS116 testing could be over-stressing the circuitry, particularly the transient suppressors intended to provide ESD protection.
8.3 Recommendations
R-1. Conduct a series of cryogenic tests to determine whether reliability issues exist with the ECO sensors. These tests should address issues surrounding the use of staked connections and passivated stainless steel surfaces.
R-2. Modify PSB pre-flight testing and incorporate checkout of transient suppressor electronics and verification of multiple power grounds.
R-3. Verify CS116 EMI / EMC testing does not overstress PSB input circuitry.
R-4. Complete a review of the PSB circuit design and ensure transient suppressor electronics are properly sized and that all parts have been screened for any GIDEP-related issues.
R-5. Ensure all PSBs have been screened for potential workmanship and assembly issues, including loose card guides and damaged flex-ribbon assemblies, and that such problems have been eliminated to the extent possible.
R-6. Determine whether power-on testing of PSB electronics without a heat-sink may have resulted in component overstress and, if so, what components are likely to be affected and how failure of those components may manifest itself in flight.
R-7. Isolate the cause of PSB S/N 112 power converter noise and inspect PSB S/N 111 for copper path damage between the signal conditioner card circuitry and electrical connector.
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A nice view....
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psloss - 9/12/2007 6:25 AM
shuttlefan - 9/12/2007 7:23 AM
Earlier it was mentioned that they may drain back down to 5% and try filling again. Could this possibly be done and still be successful today in time for a possible launch?
Even if they tried filling again, it would be for troubleshooting.
I know there's some anxiousness out there for a launch, but if you follow the shuttle program, you will learn to be patient.
I've been following the program for20 years and I AM patient. Just was curious about that option. Thanks. ;)
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Watch the webcams. They are due to RSS mate very soon.
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When is the crew scheduled to head back to Houston?
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kimmern123 - 9/12/2007 6:11 PM When is the crew scheduled to head back to Houston?
The astronauts will depart for NASA's Johnson Space Center in Houston at 5:00 p.m. EST (2200 GMT) and resume training for their space station construction flight. from Space.com
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excuse me, i tried to find the answer but got no success, are we having a rollback to the VAB???? or the ECO issue can be fixed at pad and the next launch window starts on jan 2????
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C5C6 - 9/12/2007 5:46 PM
excuse me, i tried to find the answer but got no success, are we having a rollback to the VAB???? or the ECO issue can be fixed at pad and the next launch window starts on jan 2????
That depends on the outcome of the ongoing testing/troubleshooting, doesn't it?
You can't find a definitive answer because there isn't one yet.
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Found this:
During the post-scrub news conference, Launch Director Doug Lyons said that a rollback to the Vehicle Assembly Building was not a situation managers were considering currently, and explained that the pad offers extensive access to the systems for troubleshooting and investigation.
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RSS Rotation to MATE position has been underway for a while...
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C5C6 - 9/12/2007 7:46 PM
excuse me, i tried to find the answer but got no success, are we having a rollback to the VAB???? or the ECO issue can be fixed at pad and the next launch window starts on jan 2????
lets see if the tests of today, narrow things down.. I hope the tests finally target the problem area, so that it could be understood .. based on that there may be an option to work the loading so as to get 100% repeatable /understandable results, without doing any work internally... who knows...maybe a R&R effort, maybe something that requires redesign..
I would be very mpressed if the NET Jan 2 date can be targeted..
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see you next month Atlantis
edit: Make that next year.
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Bruce - 9/12/2007 5:26 PM
1. There's lots of different rocket designs being used. OK, not many that are man-rated, but surely someone else has solved this problem of eco sensors. Is it something that can be bought elsewhere? Presumably the whole system would need to be changed, and that's not going to happen quickly.
2. Maybe there's more to this 2015 extension. Maybe NASA have said there's too much pressure to get ISS complete AND finish by 2010. Maybe someone has finally realised that NASA will look just a bit silly with a 5 year must-rely-on-soyuz plan.
3. Either design to fly safely without eco sensors.
1. not for this application
2. This was a congressman's proposal, not NASA's. There is plenty of time before 2010
3. The ECO system is for safety and can't fly without it
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Ford Mustang - 9/12/2007 7:08 PM
RSS Rotation to MATE position has been underway for a while...
Nice images Ford, as always.
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We'll go to a new thread later today, as part of the troubleshooting effort.
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Chris Bergin - 8/12/2007 1:21 PM
In the meantime, I've written up some of the MMT presentations on L2:
http://www.nasaspaceflight.com/content/?cid=5304
That is long article! :o
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Polecat - 10/12/2007 1:06 PM
Chris Bergin - 8/12/2007 1:21 PM
In the meantime, I've written up some of the MMT presentations on L2:
http://www.nasaspaceflight.com/content/?cid=5304
That is long article! :o
Not as big as the next, which will easily be the most fascinating I've written (not my writing, the quotes I'll be using).
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I have written an article about the ECO sensors and how they work. I was motivated by a lot of false info (obviously not in this forum) and my own desire to understand. The question now is where have I myself screwed up? ;)
I'd appreciate if those with a little time could have a look and pinpoint me to what is wrong. It is available at:
http://spacelaunch.gerhards.net/2007/12/space-shuttle-eco-sonsors-in-depth-view.html
Many thanks,
Rainer