Following a run of \u201cclean\u201d flights during 2008 \u2013 thanks to continued progress in reducing foam liberation from the External Tanks \u2013 the Space Shuttle Program (SSP) Flight Readiness Review (FRR) focused on the threat of ice liberation during ascent for 2009\u2019s opening mission, STS-119. This follows a near miss with a large piece of ice during STS-126.<\/p>\n<\/p>\n
An amazing amount of work has taken place with the tanks that are constructed at Lockheed Martin\u2019s Michoud Assembly Facility (MAF) in New Orleans, successfully rising to the challenge of reducing the threat of debris \u2013 mainly in the form of foam \u2013 shedding from the tanks during ascent, due to the potential of damaging impacts with the orbiter\u2019s Thermal Protection System (TPS).<\/p>\n
ET-129, which flew with Endeavour during STS-126\u2019s launch, was the cleanest tank yet, with only a few areas of minor foam loss.<\/p>\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/01\/a214.jpg\")
\u201c(4) observations elevated as Post Flight Assessment Reports (PFARs) and assessed as IFA candidates. No new failure modes identified. No constraints or corrective actions required for STS-119\/ET-127. No IFAs recommended for STS-126\/ET-129.\u201d<\/p>\n
All areas of foam loss were deemed as \u201cunderstood\u201d and relate to either cryopumping during ascent \u2013 a known condition, or small areas of manufacturing damage suffered due to \u201chigh traffic\u201d of engineers working in certain areas of the tank. Corrective actions have been noted on latter, via the FRR documentation.<\/p>\n
However, STS-126 did suffer one debris threat during early first stage flight.<\/p>\n
Although ice is a debris threat from the ET, the STS-126 event originated from Endeavour herself, according to ascent imagery. However, the debris failed to impact the vehicle.<\/p>\n
NASA educational resources (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n \u201cDuring STS-126, at approximately 26.7 seconds, debris was observed to liberate between the LH2 T-0 umbilical and port OMS pod,\u201d noted one of 43 FRR presentations, available on L2.<\/p>\n \u201cImagery analysis concluded that liberated ice measured approximately 11.5\u201d x 2\u201d,\u201d noted the presentation on the size of the ice debris. \u201cImagery and Debris Team trajectory analysis confirmed no contact with the Orbiter.\u201d<\/p>\n The T-0 umbilicals \u2013 located on each side of the orbiter \u2013 and mated to the orbiter via retractable plates in the Tail Service Masts (TSMs), which can be seen either side of the orbiter\u2019s aft.<\/p>\n As the name suggests, the T-0 umbilcals are retracted just as the vehicle is lift-offs, and it is thought the ice developed on the carrier plate of the LH2 umbilical during tanking. The ice remained with the orbiter before liberating 26 seconds later.<\/p>\n \u201cKSC led resolution team to determine root cause for STS-126 T-0 ice formation,\u201d noted the FRR presentation. \u201cDecision to perform full analysis to assess risk for future flights over range of masses and release times.\u201d<\/p>\n \u201cProduced impact conditions for Orbiter elements: Side Fuselage, OMS Pods, OMS Nozzle, Body Flap, Upper Wing, Elevon, and SSMEs (Space Shuttle Main Engines, plus RSRB (Reusable Solid Rocket Motors) and ET impacts.\u201d<\/p>\n Work is still taking place on threat analysis, following checks of the pad\u2019s GSE (Ground Support Equipment) on the Mobile Launch Platform (MLP), and on the umbilical connection area on Discovery.<\/p>\n \u201cPurge test on MLP 1 LH2 Tail Service Mast (TSM) Umbilical Helium flow test completed,\u201d noted the status of the investigation. \u201cInspection of T-0 Umbilical Carrier plate perimeter seal interface on OV-103 (Discovery) T-0 Plate completed.<\/p>\n Preventative actions for future flights will be the only outcome of the investigation, as opposed to being a threat for STS-119\u2019s launch.<\/p>\n The only threat to launch at present relates to the Flow Control Valve (FCV) changeout, which is taking place over the next week.<\/p>\n While the changeout will be performed in time for launch, flight rationale for the spare valves on Discovery \u2013 and the LON (Launch On Need) orbiter Endeavour \u2013 is still being built.<\/p>\n This issue remains the one constraint for flight as per the SSP FRR last week.<\/p>\n L2 members<\/em><\/em>: All documentation \u2013 from which the above article has quoted snippets \u2013 is available in full in the related L2 sections, now over 4000 gbs in size.<\/em><\/em><\/p>\n","protected":false},"excerpt":{"rendered":" Following a run of \u201cclean\u201d flights during 2008 \u2013 thanks to continued progress in reducing foam liberation from the External Tanks \u2013 the Space Shuttle Program (SSP) Flight Readiness Review (FRR) focused on the threat of ice liberation during ascent for 2009\u2019s opening mission, STS-119. This follows a near miss with a large piece of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[8329,9021,3610,9123,9219],"class_list":["post-41206","post","type-post","status-publish","format-standard","hentry","category-news","tag-debris","tag-et","tag-frr","tag-sts-119","tag-sts-126"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41206"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=41206"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41206\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}See Also<\/h4>\n
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![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/01\/a410.jpg\")
Engineers studied video taken of the T-0 umbilical area during lift-off, and included historical footage all the way back to STS-51L, and reviewed potential impact threats to several areas of the vehicle. Image left from STS-126\u2019s 330mb engineering launch video on L2 \u2013 angle from inside the TSM during LH2 T-0 umbilical retraction.<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2009\/01\/a312.jpg\")
\u201cDebris Transport Analysis (DTA) of ice\/frost release in work to characterize risk. Fault Tree Analysis and Block closure is in work. Assessing Ground Support Equipment hardware and process options to prevent ice\/frost or have it liberate at\/before T-0.\u201d<\/p>\n