{"id":41355,"date":"2008-07-07T18:17:12","date_gmt":"2008-07-07T10:17:12","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/discovery-ascent-trajectory-anomaly-noted-on-sts-124-ifa-review\/"},"modified":"2008-07-07T18:17:12","modified_gmt":"2008-07-07T10:17:12","slug":"discovery-ascent-trajectory-anomaly-noted-on-sts-124-ifa-review","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/discovery-ascent-trajectory-anomaly-noted-on-sts-124-ifa-review\/","title":{"rendered":"Discovery ascent trajectory anomaly noted on STS-124 IFA review"},"content":{"rendered":"<p>Shuttle Discovery\u2019s right Solid Rocket Booster (SRB) \u201ctailed off\u201d sooner than the left during the final part of first stage ascent \u2013 the IFA (In Flight Anomaly) review of the STS-124 mission has noted \u2013 causing Discovery to counter via \u201cgreater than typical steering commands\u201d.\n<\/p>\n<p>  The review, discussed at the all-powerful Program Requirements Control Board (PRCB) meeting, evaluated every single anomaly relating to what was a highly successful mission.\n<\/p>\n<p><em><img fetchpriority=\"high\" decoding=\"async\" height=\"129\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/forums\/get-attachment.asp?action=view&amp;attachmentid=13910\" width=\"600\" align=\"left\" vspace=\"5\" border=\"0\/\"><\/em><\/p>\n<p><em>**The most comprehensive collection&nbsp;of&nbsp;Shuttle, Ares, Orion&nbsp;and ISS&nbsp;related presentations and mission documentation, plus expansive daily processing documentation and updates&nbsp;are&nbsp;<\/em><font color=\"#0000ff\"><em>available to download&nbsp;on L2<\/em><\/font><font color=\"#0000ff\"><em>&nbsp;**<\/em><\/font><\/p>\n<p><font color=\"#ff0000\"><em><img loading=\"lazy\" decoding=\"async\" height=\"182\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/index.php?action=dlattach;topic=2859.0;attach=83887;image\" width=\"240\" align=\"left\" vspace=\"5\" border=\"0\/\"><\/em><\/font><font color=\"#0033ff\"><em>**Click&nbsp;here for sample of L2 menu and content**<\/em><\/font><font color=\"#ff0000\" size=\"3\"><\/font><font size=\"2\"><\/font><\/p>\n<p><em>**<\/em><font color=\"#ff0000\" size=\"3\"><\/font><font size=\"2\"><em>STS-124 L2&nbsp;Sub Section (over 3400mb) \u2013 Continuing through post flight and post mission IFA\/Mission reviews. 13 Post Flight IFA Review Presentations now available.<\/em><\/font><\/p>\n<p>**STS-125\/LON-400 L2 Sub Section Special already over 1650mb in size \u2013 special section Now Live, with over&nbsp;40 superb mission presentations. STS-125 Flight Plan (newly created) and Flight Data Files now uploaded. Mission Overview in CGI&nbsp;videos building up \u2013 starting with payload overviews.&nbsp;STS-400 Flight Plan. STS-400 EVA and mission overview Presentations (14). Daily extensive processing latest.<font size=\"3\"><\/font><\/p>\n<p><font color=\"#0000ff\" size=\"2\"><em>**STS-124 Post Flight \u2013 STS-119 Processing Latest**<\/em><\/font><font color=\"#000000\">&nbsp;\u2014 <\/font><font size=\"2\"><em>**STS-124 News Articles**<\/em><\/font><\/p>\n<p><font color=\"#0000ff\" size=\"2\"><em>**LIVE updates: Endeavour&nbsp;Dual LON and STS-126 Processing**<\/em><\/font><\/p>\n<p>     (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n<p><font color=\"#0000ff\" size=\"2\"><em>**LIVE updates on Atlantis&nbsp;STS-125 Processing Flow**<\/em><\/font><font color=\"#000000\">&nbsp;\u2014 <\/font><font size=\"2\"><em>**STS-125 News Articles**<\/em><\/font><\/p>\n<p><\/p>\n<p><em><u>STS-124 IFA Review Part 1 \u2013 SRB Tailoff:<\/u><\/em><\/p>\n<\/p>\n<\/p>\n<p>Discovery is currently processing towards the STS-119 mission next February, which will take onboard any post flight requirements gained via the IFA findings. The review is also used to aid clearance for the upcoming shuttle missions \u2013 STS-125 with Atlantis in October, and STS-126 with Endeavour in November. <\/p>\n<p>Very little is being said about the booster incident, bar that it was caused by a drop in pressure on the right booster \u2013 as expected during the burnout of the booster prior to separation. However, the tailoff occurred prior to the same event on the opposite booster. <\/p>\n<p>With the reduction in thrust on one side of the stack, Discovery was forced to react with \u2018greater than typical steering commands\u2019 \u2013 which would have resulted in the SSMEs (Space Shuttle Main Engines) and\/or the SRB TVC (Thrust Vector Control) system countering to keep the shuttle on the correct trajectory. <\/p>\n<p>\u2018STS-124: Roll Moment During SRB Tailoff: Right SRB reached 50psi 0.88 sec sooner than left SRB, resulting in greater than typical steering commands,\u2019 noted Space Shuttle Systems Engineering and Integration Office\u2019s IFA report. \u2018Associated hazard report: Ascent trajectory anomaly.\u2019<\/p>\n<p>ATK \u2013 who build the boosters \u2013 are also aware, though their IFA presentation only notes they are ready to support the subsequent investigation and closure.<\/p>\n<p>\u2018Support IFA Closure for the GN&amp;C (Guidance Navigation and Control) flight dynamics during SRM tail off (unexpected roll rate before SRB staging),\u2019 ATK noted for the Reusable Solid Rocket Motors (RSRM). \u2018Overall performance of both STS-124 (RSRM-102) motors and ATK BSMs were excellent.\u2019<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"170\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/index.php?action=dlattach;topic=3993.0;attach=78737;image\" width=\"239\" align=\"left\" vspace=\"5\" border=\"0\/\"><em><font color=\"#0033ff\">**New L2 Trailer Video, with examples of L2 content&nbsp;\u2013 <\/font><font color=\"#ff0000\">TRAILER NOW AVAILABLE \u2013 CLICK IMAGE**<\/font><\/em><\/p>\n<p>Alternatively <font color=\"#0000ff\">**CLICK HERE**<\/font> For the free trailer for the 1,900mb L2 video of an exclusive tour of the VAB, OPF and Pad.<\/p>\n<p>There are no historical notes attached on the IFA review documentation of a similar event, though sources note that the vehicle is capable of coping with such events via the flight software, which automatically detects and corrects. <\/p>\n<p>The reaction of Discovery during the STS-124 event prior to SRB separation is deemed to be within specifications. A clip from the ET cam is believed \u2013 though not confirmed \u2013 to show the roll noted *click here for video*.<\/p>\n<p><b><i><u>SRB IFA Review:<\/u><\/i><\/b><\/p>\n<p>The boosters have since been through their post flight evaluations, after being towed back to port from Atlantic ocean. No issues have been found that relate to the performance of the boosters \u2013 which is documented as \u2018excellent\u2019.<\/p>\n<p>The separate SRB IFA presentation again notes a problem with the SWAR (Sea Water Activated Release) \u2018failures to release\u2019 \u2013 which is a known condition that has occurred on a number of flights in succession now.<\/p>\n<p>The SWAR provides a method of disconnecting main parachute from SRB after splashdown, with the immersion in seawater closing an electrical circuit to release a shear pin from the riser about two seconds after immersion. <\/p>\n<p>The SWAR was fully implemented in 1998 on STS-95, in order to increase diver safety by eliminating need to cut parachute lines. Since STS-122, the problem has been heavily documented on both post flight and pre-flight Flight Readiness Review (FRR) presentations. <\/p>\n<p>The problem is believed to be associated with a known failure mechanism with the pyrotechnic train, when the primer fails to breach three millimetres stainless steel booster closure cup with enough energy to ignite charge in booster.<\/p>\n<p>Other issues noted include an aft single BSM (Booster Separation Motor) observed to be missing its graphite throat, a missing bracket on the Triple BSM forward mounting, and various missing insulation from the boosters \u2013 though only via minor liberations.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"198\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/index.php?action=dlattach;topic=1728.0;attach=87660;image\" width=\"294\" align=\"left\" vspace=\"5\" border=\"0\/\">For the first time \u2013 on recent flights at least \u2013 the electrical feed-through connectors on both boosters came into focus, with a foreign object and saltwater found on the pins that carry readings and instructions from the orbiter to the booster systems and visa versa.<\/p>\n<p>Infamous from the problems relating to the External Tanks since Return To Flight \u2013 and only focused on as the suspect hardware during STS-122\u2019s troubleshooting \u2013 the feed-through connectors on the boosters are similar in appearance.<\/p>\n<p><em>STS-122 ECO\/Feed-through connector&nbsp;related news content (all exclusives): <\/em><em>*Scrub 1*<\/em><em> \u2013&nbsp;<\/em><em>*MMT Debate*<\/em><em>&nbsp;\u2013 <\/em><em>*Scrub 2*<\/em><em>&nbsp;\u2013 <\/em><em>*Hale Memo*<\/em><em>&nbsp;\u2013 <\/em><em>*Forward Plan*<\/em><em>&nbsp;\u2013 <\/em><em>*Culprit Found*<\/em><em>&nbsp;\u2013 <\/em><em>*Tanking Test*<\/em><em>&nbsp;\u2013 <\/em><em>*Repair&nbsp;Options*<\/em><em>&nbsp;\u2013 <\/em><em>*MAF Plan*<\/em><em> \u2013 <\/em><em>*PRCB Debate*<\/em><em>&nbsp;\u2013 <\/em><em>*Plan Approved*<\/em><em>&nbsp;\u2013 <\/em><em>*Repair Schedule*<\/em><em>&nbsp;\u2013 <\/em><em>*Launch Date*<\/em><em>&nbsp;\u2013 <\/em><em>*New Issue*<\/em><em>&nbsp;\u2013 <\/em><em>*Hale Rallying Call*<\/em><em>&nbsp;\u2013 <\/em><em>*PRCB Launch Dates*<\/em><em>&nbsp;\u2013 <\/em><em>*New Connector Installed*<\/em><em>&nbsp;\u2013 <\/em><em>*Positive Test Results*<\/em><em>&nbsp;\u2013 <\/em><em>*Manifest Impacts*<\/em><em>&nbsp;\u2013 <\/em><em>*Optimism&nbsp;with forward plan*<\/em><em>&nbsp;\u2013&nbsp;<\/em><em>*Flight Rationale*<\/em><em>&nbsp;\u2013 <\/em><em>*Repairs Finalizing*<\/em><em>&nbsp;\u2013 <\/em><em>*Root Cause Confirmed*<\/em><\/p>\n<p>The foreign material found in the left aft feed-through connector has been determined as Froth-Pak foam, which is not relating to the flight \u2013 following the \u2018time of occurrence\u2019 to be determined as during disassembly. However, the notes on the right booster point to a rupture of the cable attached to the feed-through connector.<\/p>\n<p>\u2018Saltwater Found within Aft Skirt Feed Thru Cable Connector: Watertight reusable cable \u2013 Water found within jacket and opposite end of cable,\u2019 noted the IFA presentation. \u2018Suspect rupture in cable allowed water intrusion. United Space Alliance to determine cause and corrective action.\u2019<\/p>\n<p>Given the boosters impact the ocean following their separation and fall back to Earth, there is a good chance that the rupture to the cable occurred at that time, as opposed to during its flight. This will be investigated.<\/p>\n<p><b><i><u>Discovery\u2019s STS-124 IFA Review:<br \/><\/u><\/i><\/b><br \/>Only 16 items were recorded by the Mission Evaluation Room (MER) during Discovery\u2019s flight, with only a handful of those holding any relevance to her next flight. An Orbiter IFA based review expanded on all of those issues noted, along with their relation \u2013 if any \u2013 to Atlantis and Endeavour.<\/p>\n<p>The items listed included the Left OMS Secondary TVC (or gimbal) controller\u2019s \u2018failure to null in both pitch and yaw\u2019 \u2013 which is still undergoing evaluation in the Orbiter Processing Facility (OPF) in order to find a root cause.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"198\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/index.php?action=dlattach;topic=1785.0;attach=82787;image\" width=\"262\" align=\"left\" vspace=\"5\" border=\"0\/\">This issue, which had no impact to the mission, still proved to be useful for lesson\u2019s learned, as engineers on the ground worked through scenarios relating to a worse situation with the position of the OMS engine bell during re-entry \u2013 providing a ready-made plan in the unlikely event it is required in the future.<\/p>\n<p>\u2018At 0\/00:00:51 MET, both Left OMS TVC Secondary position transducers ramped from the nominal ascent stow positions (approximately +6.0 degrees for both pitch and yaw) to 0.0 degrees in both pitch and yaw axis,\u2019 noted the presentation. \u2018The change in indicated position took approximately 10 seconds. <\/p>\n<p>\u2018The primary position feedback indications remained in the nominal stow positions during the same timeframe. The left OMS was utilized for OMS assist, OMS 2, and OMS 3 (NC-1) burns as planned. OMS 2 was burned using primary TVC, and a post burn gimbal check was not performed on the left secondary TVC.<\/p>\n<p>\u2018The Left OMS TVC was parked through the EOM C.G. (End Of Mission Center of Gravity \u2013 post NC 1) and powered off. The Left OMS remained in this config until the deorbit burn. <\/p>\n<p>\u2018All remaining on-orbit single engine OMS burns were completed using the right OMS engine. During wheel touch down both indications recovered indicating an intermittent open circuit in, or to, the power supply to the OMS controller.<\/p>\n<p>\u2018Post-Flight Plan: STS-119: TVC was actuated using the secondary controller in the OPF; no issues identified. Will continue troubleshoot to isolate the open circuit or controller. STS-125\/STS-126: None.\u2019<\/p>\n<p>A sign of the level of detail the orbiters are put through during their processing is in evidence with the findings that a blown one amp fuse was the cause of an issue with Fuel Cell 3\u2019s hydrogen flowmeter.<\/p>\n<p>\u2018Fuel Cell 3 CPM (Cell Performance Monitor) and H2 Flowmeter Instrumentation Loss: The fuel cell 3 CPM substack 1, 2, and 3 measurements and the hydrogen flowmeter measurement failed to offscale low at 159\/01:18:16 GMT. <\/p>\n<p>\u2018These four measurements are powered by the mid-PCA 3 through a common fuse (F6). A 0.4 amp drop in the overall current on MPCA-3 was observed, which is consistent with the expected current for the instrumentation lost.<\/p>\n<p>\u2018Loss of this measurement resulted in loss of insight into monitoring a potential problem developing in a cell. As a workaround, the Fuel Cell Monitoring System (FCMS) was powered up daily to record and download individual cell data. <\/p>\n<p>\u2018As a result of this failure Main Bus B and Main Bus C remained bus tied after SSPTS (Station-Shuttle Power Transfer System) deactivation except for critical burns.<\/p>\n<p>\u2018Post flight plan: STS-119: The 1 amp fuse F6 in Mid PCA3 has been removed and found to be blown. Continuity and isolation checks will be conducted on the path that powers the H2 flowmeter and the CPM to further troubleshoot this problem. STS-125\/STS-126: None.\u2019<\/p>\n<p>Only one issue will require evaluation on all the orbiters in the fleet, namely a problem with the external airlock upper hatch latching difficulty, which was reported by the STS-124 crew.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" height=\"193\" alt=\"\" hspace=\"5\" src=\"http:\/\/forum.nasaspaceflight.com\/index.php?action=dlattach;topic=1728.0;attach=87659;image\" width=\"223\" align=\"left\" vspace=\"5\" border=\"0\/\">\u2018The crew reported difficulty closing and latching the External Airlock Upper Hatch on Flight Day 11,\u2019 added the IFA presentation. \u2018Attempts to position the actuator handle over the decal that indicates the correct \u2018pre-closing\u2019 position were unsuccessful, as a hard stop was encountered prior to reaching that position. <\/p>\n<p>\u2018After approximately 10 minutes of attempting various techniques, the crew was able to seat the hatch by moving the handle slightly in the latching direction. Latching was then completed successfully.<\/p>\n<p>\u2018Post Flight Actions: Troubleshooting has determined that a stop bolt in the latch mechanism is adjusted such that the actuator handle can travel approximately 405 degrees from the fully-latched position (should be approximately 440 degrees). <\/p>\n<p>\u2018Ground cycles have duplicated the crew\u2019s inability to reach the \u2018pre-closing\u2019 position. It is not yet known whether this is due to improper rigging or a problem with the rigging specification itself.<\/p>\n<p>\u2018Post Flight Plan: OV-103: Adjust stop bolt rigging and review procedures. OV-104\/105: Inspect and adjust rigging if required.\u2019<\/p>\n<p>Numerous other items in the presentation related to items such as the APU (Auxiliary Power Unit) 3 injector water cooling line thermostat, which was noted as \u2018dithering\u2019 for around half of the mission \u2013 this is being replaced ahead of STS-119.<\/p>\n<p>Also gaining a mention was the Rudder Speed Brake (RSB) Thermal Clip liberation event near the end of the mission, with a plan already in place for the replacement of the clips on Atlantis for her STS-125 mission.<\/p>\n<p>As previously reported by this site, the long-term plan to evaluate the potential of removing all the clips\/tabs from the orbiters in time for STS-126 \u2013 should it be deemed as viable.<\/p>\n<p>A second IFA review article will follow in the coming days, focusing on the performance of the External Tank (ET-128) and all debris events (from the flame trench to during ascent). <\/p>\n<p>All 13 STS-124 IFA presentations are already available to download on L2.<\/p>\n<p><font color=\"#0000ff\"><em>L2 members<\/em><\/font><em>: All documentation&nbsp;\u2013 from which the above article has quoted snippets \u2013 is available in full in the related L2 sections, updated live.<\/em><\/p>\n<p><em>**BRAND NEW STS-124 MISSION OVERVIEW MUSIC VIDEO \u2013 AVAILABLE HERE** (Free Video Section \u2013 Only requires to be logged into the forum)<br \/><\/em><br \/><em>Click here for a range of superb&nbsp;STS mission specific music videos created by Max Q videos<\/em><em>&nbsp;<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Shuttle Discovery\u2019s right Solid Rocket Booster (SRB) \u201ctailed off\u201d sooner than the left during the final part of first stage ascent \u2013 the IFA (In Flight Anomaly) review of the STS-124 mission has noted \u2013 causing Discovery to counter via \u201cgreater than typical steering commands\u201d. The review, discussed at the all-powerful Program Requirements Control Board [&hellip;]<\/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-41355","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41355"}],"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=41355"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/41355\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=41355"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=41355"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=41355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}