Endeavour heads into countdown – Atlantis window damage cleared

by Chris Bergin

Endeavour is now proceeding through the complex ballet of S0007 Launch Countdown operations for Saturday’s launch attempt of STS-127 to the International Space Station (ISS). Meanwhile good news has been reported on the damage sustained by Atlantis’ Window 5 (Pilot window), with mold impression results revealing the defects do not breach the unacceptable depth threshold, thus clearing the window for STS-129.

Endeavour STS-127 Pad Flow Latest:

Engineers have ably guided Endeavour through her pre-launch processing milestones, despite time constraints relating to turning the vehicle around after the successful tanking test at the start of the month.

No technical issues are being worked on the vehicle, with the only additional work relating to cosmetic damage observed on the left hand Solid Rocket Booster (SRB) and the removal of cracked foam from External Tank (ET-131’s) LO2 Feedline.

“Orbiter: OV-105 / ET-131 / BI-138 / RSRM-106 (Pad-A): S0071, OMS/RCS/MPS Orbital Maneuvering System/Reaction Control/Main Propulsion System) hyper pressurization for flight is complete less post ops,” noted processing information on L2.

x2“ET-131-TS-0019, the repair of cracked foam on the ET LO2 feedline began on Wednesday. Left-hand SRB paint defect repair: Sanding and sampling of the area is complete.

“Samples were taken to the lab to verify the presence of rust. Eddy current testing revealed no anomalies. Primer and top coat application are complete.”

Nominal procedures completed in the recent flow included the programming of the WLE IDS (Wing Leading Edge Impact Detection System) units, which have a primary role of “feeling” any debris impacts on the orbiter’s RCC (Reinforced Carbon Carbon) panels during ascent.

“Wing Leading Edge flight programming was successfully completed on all units. Range safety system re-programming and battery change out is complete. The flight doors have been installed.

“LOX storage tank sampling was completed (earlier in the week). APU/HPU (Auxiliary Power Unit/Hydraulic Power Unit) cart GN2 sample is complete with nominal results. The GH2 battery recharge was rescheduled for late Wednesday.”

The STS-127/2J/A mission package includes the Japanese Experiment Module – Exposed Facility (JEM-EF) and the Japanese Experiment Logistics Module – Exposed Section (ELM-ES) as well as the Integrated Cargo Carrier – Vertical Light Deployable (ICC-VLD).

Atlantis/STS-129 Processing Latest:

Positive news has been reported on the results of mold impressions taken on Atlantis’ Window 5 pressure pane, which has found the damage – suffered when a work light knob was found to be embedded between the pane and the dashboard – is not serious enough to warrant the pane’s replacement.

x3Given the challenging aspect of replacing the pressure pane, Atlantis would have expected to endure a six month impact on her processing flow inside OPF-1 (Orbiter Processing Facility).

“The window was inspected after the knob was removed. The deepest defect is approximately 0.0003” depth, the reportable depth threshold is 0.0015” and above,” noted findings from the mold impressions taken on Monday night, and acquired by L2.

Thanks to the successful removal of the knob – via the pressurization of the crew cabin in tandem with the application of dry ice to shrink the knob – no additional damage was suffered to either the pressure pane or the surrounding hardware.

Had that removal procedure failed, more intrusive methods would have been employed, which in turn had the potential to increase the damage on the pane.

“Pictures show that it is unlikely metal from the knob is still trapped in the defect,” added the findings. “Whether the coating requires replacement will be discussed.”

The news means Atlantis remains on track for a launch No Earlier Than (NET) November 12, 2009, on a mission that will deliver the Express Logistics Carriers 1 & 2 (ELC-1 and ELC -2), along with SASA and MISSE (Materials on International Space Station Experiment) 7A and 7B, to the Space Station.

Nominal processing work has continued throughout the window evaluations, highlighted by troubleshooting on the radiator flow control valve – an issue noted during Atlantis’ STS-125 mission to service the Hubble Space Telescope, along with the removal and replacement of the S-Band right-hand lower antenna.

“Ammonia boiler flushing continues and should terminate late Wednesday. Freon coolant loop 1&2 functional checks were completed on Tuesday. Engineering is evaluating data results,” noted processing information on L2.

“S-band thermography was completed Tuesday. S-band antenna removal picked up Tuesday night. Re-installation is planned for Thursday.”

Discovery/STS-128 Processing Latest:

x4Discovery is preparing to rollover to the Vehicle Assembly Building (VAB) on July 14, ahead of her August STS-128 logistics mission – carrying the MPLM (Multi-Purpose Logistics Module) Leonardo primary payload to the ISS.

“Structural leak checks will be completed this week,” noted the Shuttle Standup/Integration report on L2, citing United Space Alliance (USA) Ground Operations. “Orbiter final power down occurred Tuesday at 1300 EDT.

“Weight and CG (Center of Gravity) work done on Wednesday, and the vehicle will transfer to the OTS (Orbiter Transporter System) on Thursday, July 9. The vehicle should be ready to roll to the VAB on July 14.”

Ahead of transferring the veteran orbiter on to her taxi ride to the VAB, engineers worked through the final pressurization of the vehicle’s landing gear. All went to plan, bar an issue with a transducer associated with the reading of the tire pressures.

“Final tire pressure for flight, Nose Landing Gear was completed last night. Main Landing Gear will be completed late Wednesday.

“Pressure transducer milli-volt reading does not correlate to tire pressure. Troubleshooting plan is to take the pressure panel to the highest acceptable pressure band for the tires and then check the transducer milli-volt reading.

“If bad then the plan is to take the pressure panel to the lowest acceptable pressure band for the tires and if the transducer milli-volt reading is still bad then we’ll reconfigure with a different pressure panel.”

The actual mating of Discovery to the OTS will occur during first shift on Thursday, with Call to Stations (CTS) at 6am local time.

L2 members: 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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