Endeavour rollaround moved forward to Thursday – FRR concludes

by Chris Bergin

The unique transfer of Endeavour and the STS-126 stack from Pad 39B to 39A has been moved forward to Thursday at 8am. Meanwhile, the main SSP FRR has concluded with no major issues reported.

A key milestone for the move is due to take place over the next 24 hours, with the arrival of STS-126’s “Leonardo” Multi-Purpose Logistics Module (MPLM) at 39A. It is scheduled to be loaded into the Payload Changeout Room (PCR) on Wednesday – pending acceptable weather conditions.

“At Pad B, will do final power up today and a software load. Continuing with preps to rollover,” noted Ground Operations (L2) on Tuesday. “Still planning on rolling over from Pad B to Pad A on Saturday, October 25.

“Prior to the arrival of the vehicle, will be getting the payload to the pad on Wednesday evening. Will get that transferred into the PCR.”

Several scenarios are being worked, should unacceptable weather delay either the arrival of STS-126’s payload at the pad, the rollaround, or both.

“As of yesterday, the weather forecast is not favorable for payload delivery and roll over preparations, therefore, several scheduling scenarios are being considered,” added Tuesday processing information on L2.

“Currently, the STS-126 payload (MPLM) is scheduled to be transferred to Pad A tomorrow. Call to Stations (CTS) for roll over preparations occurred yesterday at 1200 EDT. OV-105 (Endeavour) is scheduled to be rolled from Pad B to Pad A on Saturday, 10/25 (weather permitting).”

UPDATE: Wednesday morning processing information notes a telecon will take place later today on the potential to move the rollaround up to Thursday, in order to avoid unacceptable weather conditions at the weekend. This has since been approved.

Issues being worked on Endeavour currently hold no constraint to the launch date target of November 14, although one problem is being worked at Pad 39B – and needs to be resolved ahead of the rollaround.

“Failed Leak Check on Ground Cooling System Lines 20 and 21 during S0004 in VAB. At Pad B while looking for a leak it was discovered that the Freon lines were misconfigured,” added processing information.

“Work is in progress to reconfigure Freon lines and change supply line filter. Currently it is a constraint for move to Pad A.”

This issue relates to a ground cooling unit, which perform the same function the orbiter’s radiators on orbit – cooling the electronics and other heat producing hardware in the orbiter. This unit was connected to the orbiter with the inlet and outlet lines reversed.

Given this unit is a GSE (Ground Support Equipment) freon heat exchanger loop, the system would still basically function if left as-is. However, the supply line filter – as are the incorrectly connected lines – would benefit from being correctly configured, thus engineering work is taking place.

Once the orbiter is launched, the heat exchanger is removed from the loop and thus would not cause an in-flight problem. During launch and landing heat rejection is also accomplished by the Flash Evaporator System (FES).

Meanwhile, work on the fillerbar that was damaged during a leak on Endeavour’s F5R thruster is not expected to take more than a day or so, and will likely be carried out once the STS-126 stack has taken up occupancy on 39A.

All the affected TPS (Thermal Protection System) – which related to around 16 tiles on Endeavour’s nose – have been cleaned and deemed to be undamaged by the “ooze” that leaked from the thruster.

Also under discussion is the potential of removal and replacement work on the command receiver/decoders for STS-126’s SRBs (Solid Rocket Boosters). This relates to Range Safety requirements.

“Late last week in a discussion with the Range, the command receiver/decoders were identified as going beyond 180 days since bench testing at launch time,” added the latest Shuttle Stand-up/Integration report on L2. “That is a goal established with the Range.

“The Range basic requirements include full up test of equipment 180 days prior to launch. Twelve years ago, the Range requirement was tailored, and they allowed that as a goal. In discussions, the Range established a preference to make that a requirement again for NASA.

“Will meet with them to discuss this. If they do require it, we’ll have to R&R the command receiver/decoders from STS-126.”

Ahead of the rollaround of Endeavour, STS-126 underwent a two day SSP FRR (Space Shuttle Program Flight Readiness Review).

No major issues are in need of discussion, with current pre-emption of topics previously discussed over the past few weeks – bar the addition of a debate surrounding a new crew survival radio.

“Completing review of FRR charts on Special Topics this afternoon with Johnson Space Center (JSC),” noted one department on the stand-up report. “Has to do with potential for non-flight washers and LESS carrier panel assembly.

“Charts will show have evaluated three items for flight rationale: panel deflection and analysis show that will not be a problem, fastener integrity – completed analysis to show have positive margin, and panel retention – evaluated using a Monte Carlo approach to show potential for tolerance stackups to prevent engaging locking feature. Have confidence the panel will stay on vehicle.

“On the new survival radio that are trying to fly on STS-126, there were three batteries (out of 30) that look like they discharged during testing. They were hot when they came out of testing. Are dissecting those batteries and sending out to labs to understand what happened during the test.”

“Had Engineering Directorate pre-FRR last Friday, with no major issues,” added the Chief Engineer. “Talked much about the carrier panel and crew survival radio battery issue. Will coordinate with Orbiter, but will probably bring to FRR.”

The FRR concluded during Wednesday, with no major issues noted.

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

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