Discovery deservicing in OPF-3 – TPS assessment positive
Following her 13 day mission in space on STS-119, Discovery is being deserviced inside her Orbiter Processing Facility (OPF-3), ahead of her next mission, STS-128. Close inspections of her Thermal Protection System (TPS) created a list of work that will be carried during her 101 day processing flow.
Discovery touched down on KSC runway 15 at 15:14:45 local time on Saturday, completing a successful mission installing the final solar array truss to bring the ISS to full power.
De-orbit burn, re-entry, and landing performance were all nominal, with entry controllers reporting the flagship orbiter enjoyed a faultless return home.
Once safed at the Shuttle Landing Facility (SLF), S0069 Integrated Roll-In operations picked up. Orbiter tow first motion from the SLF to OPF3 was at 18:46 local, before she was spotted in OPF-3 at 20:55. Fuel cell shutdown/ground power transfer was completed at 00:30 on Sunday.
TPS assessment began at 15:40 on Saturday, with engineers documenting most areas of Discovery’s heatshield, prior to being towed back to the OPF.
“Overall vehicle looked good. There was one protruding Ames gap filler, it was the gap filler seen on orbit,” noted the TPS assessment report on L2. “There were three instances of missing putty repairs.”
A special Boundary Layer Transition (BLT) Detailed Test Objective (DTO), which involved one tile on Discovery’s belly protruding slightly, was also inspected, with no damage reported in the local area.
“BLT protuberance did not exhibit significant slumping or erosion,” added the report. “Structural integrity was maintained. BLT protuberance tile did not appear slumped, although minor glazing was noted along the trailing edge of the fin. Streaking was noted along 3 tiles downstream of the protuberance. “
Also reported were the thermal barriers on the Nose Landing Gear Door (NLGD), which provided close up views of an item of interest found during Flight Day 3’s RPM photography.
“On orbit ‘fray’ on Forward NLGD thermal barrier was actually frayed edge of patch, no damage to weave of fabric noted,” added the report, before listing other areas of interest on the forward section of Discovery.
“Right portion of Arrowhead Blanket was protruding .05” around attach point. Chin panel -441 gap filler had one tear on the right side approximately 1” long. Right hand side gap measurement was .180, left hand side gap measurement was .170, and the center measurement was .210.”
“Unknown marking on the V070-391035-313 tile was an orange marking approximately 2” long, no protrusion noted. Large amount of degradation seen on FRCS (Forward Reaction Control System) thermal barrier R4R. Damage was noted in previous repair location.”
For Discovery’s Main Landing Gear Doors (MLGS), the thermal barriers also appeared nominal, while a gap filler – noticed in the RPM photography, actually survived re-entry, as opposed to coming lose during Flight Control Surface checkouts on Flight Day 12, or during re-entry.
“Gap filler on the left hand inboard elevon was still present. The protrusion appeared to be the same as on orbit with no obvious effects of overtemp. The gap filler was confirmed to be 3 plies of Ames.”
“Left hand inboard elevon damage appeared to be the same as on orbit, with and estimated depth of .3-.4”. Rounding of damage edges indicates evidence of possible heating.*
Other items of interest included missing putty repairs on three tiles – which can be expected, a broken “piano key” tile on the body flap, and a protruding gap filler on one of Discovery’s OMS Pods – which have performed well since the couple of incidents with torn stitching between the tiles and the blankets.
“Discolorations noted on orbit aft of the LH ETD were not noted as abnormal on the runway,” the report added. “Piano key tile above the body flap had a large portion of the cantilever broken off.
“Tile between engines 2 and 3 had an edge broken off. Piece of material debris identified on top of the RH (Right Hand) side of the body flap. Source unknown (see left image).
“OMS protruding gap filler noted on orbit as 500-001 was visibly frayed. It is notable that this portion of the gap filler was not noted as protruding on orbit.”
Further inspections on Discovery’s TPS are being conducted in the OPF, ahead of final deservicing tasks and preparations to enter her into the STS-128 processing flow, which has technically started with post STS-119 work.
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. STS-119 L2 Section includes same collections of all MMT presentations, images and video, now over 3,000 mb in total.