Author Topic: STS-121: July 1 Launch SCRUB (Read 133986 times)

Chris Bergin · « **on:** 07/01/2006 10:52 am »

Morning.

Here we go with the first attempt.

Updates into here.

Stardust9906 · « **Reply #1 on:** 07/01/2006 10:54 am »

psloss · « **Reply #2 on:** 07/01/2006 11:03 am »

Latest report: LOX is about 20% full, LH2 about 25%, and the ECO sensors look good...

HKS · « **Reply #3 on:** 07/01/2006 11:03 am »

NASA TV say that ECO sensors are looking good so far

20% LO2 in the tank
25% LH2 in the tank

Stardust9906 · « **Reply #4 on:** 07/01/2006 11:04 am »

40% chance of not meeting weather criteria for launch.

Stardust9906 · « **Reply #5 on:** 07/01/2006 11:22 am »

Tank now approximately 1/3 full. No problems with ECO sensors up to now.

Chris Bergin · « **Reply #6 on:** 07/01/2006 11:27 am »

The projected problems with the ECOs won't occur until later, if they are going to fail.

They've obviously gone "WET" - which is what they should do. Problem will occur if they switch "DRY" at any point prior to launch.

DaveS · « **Reply #7 on:** 07/01/2006 11:35 am »

Quote

Chris Bergin - 1/7/2006 1:14 PM

The projected problems with the ECOs won't occur until later, if they are going to fail.

They've obviously gone "WET" - which is what they should do. Problem will occur if they switch "DRY" at any point prior to launch.

Well, actually not. What they will do is take all 8 sensors to a DRY state through the sim circuit and see if they do that. That is what got the first 114 launch attempt when LH2 ECO sensor#2 got stuck and indicated WET when it was commanded to go DRY.

Stardust9906 · « **Reply #8 on:** 07/01/2006 11:36 am »

Tank now 40% full. Troubleshooting a heater on an aft thruster.

James (Lockheed) · « **Reply #9 on:** 07/01/2006 11:43 am »

DaveS, That was 114.

The reason they switched through the SIM was due to intermittent readings. SIM commands will be used for troubleshooting.

Chris Bergin · « **Reply #10 on:** 07/01/2006 11:49 am »

MMT latest: Bottomline: No formal constraints to STS-121 launch were identified. All MMT members were GO.

Update on the "Bird Hold": Bird plan – As a follow on to the Level 1 FRR action, a criteria has been developed to hold for 4 or more birds (moderate) consistently within 75 ft of vehicle. There is a low probability of this occurring based on bird count/location over the last few days in the afternoon timeframe.

Chris Bergin · « **Reply #11 on:** 07/01/2006 11:59 am »

POSSIBLE SCRUB.

Management meeting now taking place.

More when I get it.

Chris Bergin · « **Reply #12 on:** 07/01/2006 12:01 pm »

Teleconference called. Orbiter RCS heater problem

psloss · « **Reply #13 on:** 07/01/2006 12:01 pm »

Is this the issue with the verniers that we heard about earlier?

You could very faintly hear some discussion a few hours ago...I heard that they needed someone in the crew module to do further troubleshooting...obviously can't do that until stable replenish...

Chris Bergin · « **Reply #14 on:** 07/01/2006 12:01 pm »

Source: "Possibility of scrub due to Orbiter RCS heater problem.

"There is some discussion over whether or not to continue to prepress (to test the prepress system) if we do scrub; most of the MAF (Michoud Assembly Facility) people are against (testing the prepress in a scrub senario)."

Chris Bergin · « **Reply #15 on:** 07/01/2006 12:09 pm »

Waiting to hear more. But it currently looks like we are close to a scrub due to the RCS heaters.

The MAF talk is to continue to test the tank to prepress - to see how the tank performs, then continue with the stand-down.

Boston Shuttle Head · « **Reply #16 on:** 07/01/2006 12:19 pm »

Just looking for a description as to what the RCS heaters do and why they are so critial to launch. Any explanation would be appreciated.

Stardust9906 · « **Reply #17 on:** 07/01/2006 12:21 pm »

Flightstar · « **Reply #18 on:** 07/01/2006 12:22 pm »

Troubleshooting ongoing with the heater.

psloss · « **Reply #19 on:** 07/01/2006 12:23 pm »

PAO referred to it as "the heater on the vernier control system on the left OMS pod"; troubleshooting ongoing...

(Reference edited back out; better reference below)