**The most comprehensive collection of STS-117 onwards related presentions and mission documentation, plus expansive daily processing documentation and updates are <\/em>available to download on L2<\/em><\/font> ** Including five presentations and surrounding updated information on the COPV issue.<\/font><\/em><\/font><\/p>\n **LIVE news updates on Atlantis STS-117 PAD FLOW \u2013 LIVE**<\/font><\/em><\/p>\n **LIVE news updates on Endeavour STS-118 (LON-318) Processing**<\/font><\/em><\/p>\n **LIVE news updates on Discovery STS-120 (LON-320) Processing**<\/font><\/em> <\/font><\/p>\n These tanks are around 50 percent lighter than their metal versions, which ultimately aided how much payload the orbiters could carry when they were designed. They were initially certified for 10 years, before having their lifetime extended. <\/font><\/p>\n A review, which was conducted by a team led by Dr. Jim Sutter (Glenn Research Center) and Dr. Brian Jensen (Langley Research Center) in 2004, found that there was an increased risk of a COPV failing. At the time it was deemed that if a tank ruptured, it would lead to the loss of the orbiter. <\/font><\/p>\n \u2018A 2004 NESC review of Orbiter COPV stress rupture certification identified \u2018stress rupture failure\u2019 as an area of increased risk,\u2019 noted NASA documentation this month. \u2018Stress rupture is a sudden catastrophic failure mode of Kevlar-wrapped COPVs that can occur at normal operating pressures (individual Kevlar fibers can weaken over time). <\/font><\/p>\n \u2018WSTF test of a 40\u201d COPV in 2006 measured a volume growth of 325 cu in, vice a design spec of 139 cu in. This concern prompted measurements of the five 40\u201d tanks on OV-104 (Atlantis), and two MPS tanks, s\/n 6 & 7, measured ~340 cu in volume growth. The other 40\u201d COPV tanks ranged from 178-286 cu in volume growth.\u2019 <\/font><\/p>\n It is understood that those tests at WSTF showed that a tank failure would not lead to the loss of the orbiter during a failure event, although the evaluations that have followed have been solely aimed at ensuring such tank failure scenario was not likely to happen. <\/p>\n \u2018We\u2019ve been working on the science of COPVs for several months now. We did discover that we have a risk factor in these older tanks that were probably over-stressed in their initial tests way back 25 years ago,\u2019 said shuttle manager Wayne Hale recently. <\/font><\/p>\n \u2018We have a pair of tanks that we have sitting in reserve that we took to the White Sands Test Facility (WSTF) \u2013 and we\u2019ve been expecting potential replacements for the fleet. We\u2019re talking with other folks that have used COPVs in other applications.\u2019 <\/font><\/p>\n The COPVs of most concern are the 40\u201d OMS\/MPS tanks, as these are the highest stressed COPVs and the largest contributor to stress rupture risk. However, NASA are confident the tanks are safe to fly. <\/font><\/p>\n \u2018We believe that we have an adequate level of safety for the upcoming flights, and we have a long program of tests to look specifically at what to do to mitigate these problems,\u2019 added Hale. <\/font><\/p>\n \u2018We built all the tanks that we thought we\u2019d need, and the vendor has frankly gone out of the business of building those tanks some number of years ago, so the question is what source of operational things could we do with lower pressures and so forth, in order to mitigate or reduce to the lowest possible factor the risk that we have a problem with one of those tanks.\u2019 <\/font><\/p>\n Ahead of the upcoming STS-117, and after Hale\u2019s earlier comments, the all-powerful Program Control Requirement Board (PRCB) looked at one area of mitigation \u2013 the offloading of some of the helium \u2013 which is vital for safe engine shutdown \u2013 contained in some of the COPVs.<\/font><\/p>\n <\/p>\n <\/font><\/p>\n \u2018(An) action was issued by the PRCB to determine if some amount of MPS Helium offload could help improve the reliability for the COPV tanks,\u2019 noted NASA information. \u2018It was determined analytically that even a 200 psi Helium offload did indeed prove reliability but not significantly. <\/font><\/p>\n \u2018MOD (Management Operations Directorate) recommended against any MPS Helium offload, mainly due to shortened guaranteed engine run time \u2013 which could be significant for an Engine-out RTLS (Return To Landing Site) abort case. <\/font><\/p>\n <\/p>\n \u2018The PRCB recognized that the small increase in COPV reliability from an MPS Helium offload was more than offset by the increased risk to Engine-out cases during ascent and concurred with the no offload recommendation.\u2019<\/p>\n <\/font><\/p>\n With the latest data showing that there is an adequate level of safety with the COPVs, STS-117 will proceed as planned. In fact, opening PRCB documentation seen at the start of the year showed the risk factors were extremely small. <\/font><\/p>\n The only additional related issue that was evaluated on Atlantis was observed rippling in the COPV\u2019s titanium liners on one of her COPVs. This tank will be replaced on Atlantis after STS-117, while two more tanks will be replaced on Discovery, ahead of STS-120. **INFINITY: 10 minute STS MUSIC VIDEO**<\/font><\/em><\/font> \u2013 COMING SOON: Atlantis\/Starlight. **NASASpaceflight.com Job Opportunities**<\/em><\/font><\/em> <\/font><\/em><\/p>\n <\/font><\/em><\/p>\n","protected":false},"excerpt":{"rendered":" Shuttle managers have opted against offloading the amount of helium stored in Atlantis\u2019 Composite Overwrap Pressure Vessels (COPVs), which was initially seen as a way of potentially increasing the reliability of the tanks inside the orbiter\u2019s MPS (Main Propulsion System). The decision not to offload the amount of helium was taken after evaluations showed it […]<\/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":[],"class_list":["post-41710","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41710"}],"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=41710"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41710\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}In all, orbiters have 24 of these tanks, which are kevlar-wrapped storage tanks for helium (He) and nitrogen (N2) gas. These tanks \u2013 in various sizes and used at various pressures \u2013 are located around the orbiter, mainly in the MPS, Reaction Control System (RCS) and Orbital Maneuvering System (OMS). <\/font><\/p>\n
\n<\/font><\/p>\n<\/font>**Ride home through the fire and plasma of re-entry with Atlantis on STS-115 \u2013 And now also with Discovery on STS-116 \u2013 TWO Stunning high quality 2hr, 355mb videos \u2013 from deorbit burn to post landing**<\/font><\/font><\/p>\n
![\"\"](\"http:\/\/www.nasa.gov\/centers\/glenn\/images\/content\/159752main_heliumtank_185x139.jpg\")
The PRCB decided against the move, following evaluations that showed the increase in reliability was small, and offset by the increased possibility of a unscheduled engine-out situation, which would be more than undesirable.<\/p>\n
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