{"id":37969,"date":"2019-07-19T19:42:48","date_gmt":"2019-07-19T11:42:48","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/sts-93-at-twenty-years-i-had-to-hit-the-button\/"},"modified":"2019-07-19T19:42:48","modified_gmt":"2019-07-19T11:42:48","slug":"sts-93-at-twenty-years-i-had-to-hit-the-button","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/sts-93-at-twenty-years-i-had-to-hit-the-button\/","title":{"rendered":"STS-93 at Twenty Years: \u201cI had to hit the button!\u201d"},"content":{"rendered":"<p>In the span of a few seconds, a smooth countdown to launch Space Shuttle Mission STS-93, a five-person crew, and the Chandra X-Ray Observatory abruptly ended twenty years ago just before ignition of Orbiter Columbia\u2019s three Space Shuttle Main Engines (SSME).<\/p>\n<p>An indication that hydrogen gas was leaking into the orbiter\u2019s aft compartment where the engines were mounted popped up on a systems engineer\u2019s computer screen as pre-liftoff water began to be poured into the launch pad flame trench.<\/p>\n<p>At T-10 seconds, the Ground Launch Sequencer (GLS) gave Columbia\u2019s flight computers the go to start the engines and the hydrogen burn off igniters started as another precursor to main engine ignition that occurs just under seven seconds from liftoff. Starting the engines with leaking hydrogen could make the situation worse, so with no time to lose, primary hazardous gas system engineer Ozzie Fish called out on the Shuttle launch team\u2019s main voice loop to stop everything.<\/p>\n<p>It could take a second or two to manually stop a Shuttle launch countdown, which fell on primary GLS engineer Barbara Kennedy to make happen by pushing a button on her console to cutoff the countdown.<\/p>\n<\/p>\n<p><iframe title=\"STS-93 RSLS HOLD at T-7 seconds - Columbia July 20, 1999\" src=\"https:\/\/www.youtube.com\/embed\/IeM_ujG7gVg?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen=\"\" name=\"fitvid0\" data-gtm-yt-inspected-14=\"true\" data-gtm-yt-inspected-21=\"true\"><\/iframe><\/p>\n<p>The indication of a leak turned out to be a false positive but the quick reaction of the pair was able to stop the launch sequence less than half a second before the first main engine start command, saving the launch team from a weeks-long turnaround after an \u2018on-the-pad\u2019 engine shutdown.<\/p>\n<p>Instead, Columbia was ready to try again in two days.<\/p>\n<p>GLS overview<\/p>\n<p>The Ground Launch Sequencer automated all the fast-paced activity during the last nine minutes of the terminal countdown. The software automatically conducted the final sequence of actions required to get the Shuttle ready for ignition of its engines and liftoff. In addition to sending commands to vehicle and ground support systems to perform actions on a specific timeline, the GLS also monitored all of the critical ground and vehicle parameters during that time to enforce a pre-determined set of Launch Commit Criteria.<\/p>\n<p>Aerospace &amp; Defense<path d=\"M7.59009 18.59L9.00009 20L17.0001 12L9.00009 4L7.59009 5.41L14.1701 12\" style=\"animation: initial !important; background: initial !important; border: 0px !important; box-shadow: none !important; color: inherit !important; cursor: inherit !important; direction: inherit !important; display: inline !important; fill: currentcolor !important; filter: initial !important; float: none !important; margin: 0px !important; opacity: initial !important; outline: 0px !important; overflow: initial !important; padding: 0px !important; stroke: initial !important; transform: initial !important; vertical-align: initial !important; visibility: inherit !important;\"><\/path>Astronomy<path d=\"M7.59009 18.59L9.00009 20L17.0001 12L9.00009 4L7.59009 5.41L14.1701 12\" style=\"animation: initial !important; background: initial !important; border: 0px !important; box-shadow: none !important; color: inherit !important; cursor: inherit !important; direction: inherit !important; display: inline !important; fill: currentcolor !important; filter: initial !important; float: none !important; margin: 0px !important; opacity: initial !important; outline: 0px !important; overflow: initial !important; padding: 0px !important; stroke: initial !important; transform: initial !important; vertical-align: initial !important; visibility: inherit !important;\"><\/path>Space Technology<path d=\"M7.59009 18.59L9.00009 20L17.0001 12L9.00009 4L7.59009 5.41L14.1701 12\" style=\"animation: initial !important; background: initial !important; border: 0px !important; box-shadow: none !important; color: inherit !important; cursor: inherit !important; direction: inherit !important; display: inline !important; fill: currentcolor !important; filter: initial !important; float: none !important; margin: 0px !important; opacity: initial !important; outline: 0px !important; overflow: initial !important; padding: 0px !important; stroke: initial !important; transform: initial !important; vertical-align: initial !important; visibility: inherit !important;\"><\/path>\n<p>     (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n<p>Liftoff of the STS-93 mission was scheduled overnight from July 19 into July 20, during the local midnight hour at the Kennedy Space Center (KSC). One group of GLS engineers was on console in Firing Room 1 of the Launch Control Center at KSC in the middle of the afternoon on the 19th, as other members of the launch team began remotely loading the External Tank of the Shuttle vehicle with its liquid, cryogenic propellants on Launch Pad 39B.<\/p>\n<p>For STS-93, Kennedy, who was with United Space Alliance at the time, got the assignment to be the primary GLS. \u201cI had worked the prime seat before so it wasn\u2019t new to me in any way,\u201d she said in a recent interview.<\/p>\n<p>\u201cIt was a routine flow that we had performed for STS-93 but it was more exciting because it was the first woman commander with Eileen Collins at the lead and Jeff Ashby as the pilot, so that was kind of neat,\u201d Kennedy added. \u201cWith doing some pilot training in the past I really thought that that was superb that I was able to work the prime seat for GLS that day to help her get the Chandra X-Ray Telescope out into orbit, so that was quite an honor to be sitting in that seat when Eileen Collins was the first commander.\u201d<\/p>\n<p>\u201cIt was pretty much as I recall a standard Ground Launch Sequencer configuration that day and as we moved through the count we would do standard events and I don\u2019t remember anything anomalous that happened early in the flow \u2014 it could have been, it was a lot of years ago,\u201d she noted. \u201cWe were just excited to be there for that day.\u201d<\/p>\n<p>\u201cWe would have never known close to T-0 that we would have had an indication that we would have to react very quickly to that anomalous condition that we had not seen before.\u201d<\/p>\n<p><img fetchpriority=\"high\" decoding=\"async\" aria-describedby=\"caption-attachment-62283\" class=\"wp-image-62283 size-full\" src=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998.jpg\" alt=\"\" width=\"2094\" height=\"1343\" srcset=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998.jpg 2094w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998-350x224.jpg 350w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998-546x350.jpg 546w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998-768x493.jpg 768w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998-1920x1231.jpg 1920w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/FR1-Forward-1998-1170x750.jpg 1170w\" sizes=\"(max-width: 2094px) 100vw, 2094px\"><\/p>\n<p id=\"caption-attachment-62283\" class=\"wp-caption-text\">Credit: NASA.<\/p>\n<p><em>(Photo Caption: Firing Room 1 in 1998. The back row of consoles, including where the GLS group was stationed, are not visible from this point of view.)<\/em><\/p>\n<p>The GLS group worked at the Integration Console. \u201cWe\u2019re a part of what they call the Integration Console and they have several of the senior engineers working there and they\u2019re designed to integrate all problems and say \u2018we\u2019re go for launch,\u2019 Kennedy said.<\/p>\n<p>Their console area was in the back of the firing room. \u201cAll the way in the back, farthest from the windows,\u201d she noted.<\/p>\n<p>\u201cThe Ground Launch Sequencer folks are three people on the prime team and then three people on the earlier team. When they start tanking at T-6 hours and filling up the External Tank with the LOX (liquid oxygen) and LH2 (liquid hydrogen) fuel basically they have a early pre-setup and monitoring of all parameters in the launch sequencer and then the prime seat or \u2018hot-seat\u2019 people that are going to do the terminal count come in at T-3 hours so they\u2019re a little more fresh and ready to react,\u201d she noted.<\/p>\n<p>\u201cSo that\u2019s basically what we did when we worked the prime seat, it was T-3 hours, walk in the door and the team goes \u2018all right, GLS is here!\u2019 And about that time the crew is also getting suited up and ready to board the spaceship.\u201d<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-62284\" class=\"wp-image-62284 size-full\" src=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite.jpg\" alt=\"\" width=\"1548\" height=\"1020\" srcset=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite.jpg 1548w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite-350x231.jpg 350w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite-531x350.jpg 531w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite-768x506.jpg 768w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/Firing-Room-Integration-Console-Composite-1170x771.jpg 1170w\" sizes=\"(max-width: 1548px) 100vw, 1548px\"><\/p>\n<p id=\"caption-attachment-62284\" class=\"wp-caption-text\">Credit: NASA.<\/p>\n<p><em>(Photo Caption: A composite diagram showing the layout of the consoles in Launch Control Center Firing Rooms for Space Shuttle launches (upper left), and the seating chart for the Integration Console, which was in the far back\/right in the Firing Room (Firing Room 1 was used for STS-93). The GLS engineers were seated with Shuttle test and project engineers.)<\/em><\/p>\n<p>The sequencer is not active until later in the countdown, and while the crew is driven out to the launch pad to board the Orbiter, the GLS Group is setting up the software for the specific mission. \u201cWhen GLS Prime team comes in at T-3 hours we would initiate the launch sequencer, do the pre-sequencing events, set up what was going to be the parameters for that day for that specific vehicle, and then we would move on to activate critical monitoring,\u201d Kennedy explained.<\/p>\n<p>\u201cAround the two-hour time period we would activate thousands of parameters and what their limits were,\u201d she said. \u201cYou begin with pre-sequencing events and activating parameters and constantly verifying a group of parameters and sometimes doing a \u2018one-shot\u2019 on other parameters just to see how other things are going and these are all in what they call the Description Document, the GLSDD.\u201d<\/p>\n<p>\u201cThose were all agreed upon for that flow, and so as you moved through the sequencing as some things might not be crucial for that launch, so you would mask out or bypass anything that was not [relevant] for that particular mission, so you had a configuration that was already set and agreed upon by NASA. As the launch progressed sometimes those parameters were changed to a different phase of the launch countdown and we would update those parameters and always field any issues coming in, so as you\u2019re walking through the launch countdown, getting down into T-20 minutes, different configurations were required and basically that\u2019s how the sequencer worked is that you did certain things in an order that was already pre-approved.\u201d<\/p>\n<p>\u201cIt was very routine many times, so it was not a surprise on any of these things that you had to change a configuration, it was pre-approved usually,\u201d Kennedy said.&nbsp; In addition to mission-specific parameters, mission or orbiter or situation-specific data may need to be ignored.<\/p>\n<p>\u201cFor an out-of-tolerance you would mask that for the day or you know if you had four parameters and you knew one was bad there was a way in the sequencer you could go into the table and simply mask out one of them to vote good if you wanted it or vote bad, so we had the capability in the software to do that,\u201d Kennedy explained. \u201cAlso for the sequencing, you could skip over line items in the sequencer; for example, if you had a powered payload or if you didn\u2019t have a powered payload, you would want to activate the things being monitored on a powered payload or conversely not being monitored.\u201d<\/p>\n<p>\u201cSo there were different configurations in the software and that was what was so neat about the Ground Launch Sequencer, we had a million lines of code but you had a lot of flexibility.\u201d<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-62285\" class=\"wp-image-62285 size-full\" src=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01.jpg\" alt=\"\" width=\"2046\" height=\"1534\" srcset=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01.jpg 2046w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01-350x262.jpg 350w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01-467x350.jpg 467w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01-768x576.jpg 768w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01-1920x1440.jpg 1920w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93-Composite-01-1170x877.jpg 1170w\" sizes=\"(max-width: 2046px) 100vw, 2046px\"><\/p>\n<p id=\"caption-attachment-62285\" class=\"wp-caption-text\">Credit: NASA.<\/p>\n<p><em>(Photo Caption: Images of the fully-loaded STS-93 Shuttle vehicle during the countdown for the first launch attempt taken by the Final Inspection Team from the Pad 39B service structure. The team went to the pad after the External Tank was filled and in stable replenish mode to inspect the vehicle.)<\/em><\/p>\n<p>The GLS was activated at T-45 minutes. \u201cYou would move through the countdown and various things on the vehicle would be done, cycling vent doors and as you moved through the GLS milestones going down into T-9 minutes we would verify that all systems were go before we picked up the count at nine minutes,\u201d Kennedy said. \u201cSo there was a built-in hold, both at [T-minus] 20 minutes and at T-9 minutes to ensure that you had finished troubleshooting any anomalous conditions and that you were ready to go.\u201d<\/p>\n<p>The GLS auto-sequence started at T-9 minutes and counting and was in control of the terminal launch sequence until T-31 seconds when it handed over primary control to the vehicle\u2019s flight computers located in the Orbiter. \u201cAs you\u2019re progressing and doing all these sequenced events, they\u2019re in order, they\u2019re run the same way every countdown and that\u2019s how it works in all of aerospace is that you have a known sequence and it should be pretty much hands-off, you shouldn\u2019t have a human in the loop for standard events like that, it\u2019s more efficient for the computer and the software to actually work per the countdown clock and sequence those events,\u201d Kennedy said.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-58466\" src=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/10\/L2-banner@2x.jpg\" alt=\"\" width=\"4500\" height=\"2532\"><br \/>\nThe prime GLS operator was one of the voices Shuttle launch viewers would hear during those final nine minutes of the countdown; as the sequencer passed through the different GLS milestones and verified that all the Launch Commit Criteria was being met, the GLS operator would make that call on the voice loop to inform the rest of the launch team. \u201cYou\u2019re moving through T-9 minutes and the auto-sequence has been initiated and of course you\u2019re going to go for the OAA (Orbiter Access Arm) retract at seven minutes and thirty seconds, then the APU start happens at five minutes,\u201d Kennedy said.<\/p>\n<p>\u201cIf any anomalous condition occurs before that time you would stop at five minutes before you initiated APU start.\u201d The GLS engineers were monitoring their screens for the nominal progression through the milestones and anything not-so-nominal.<\/p>\n<p>\u201cWe had another main screen that the other GLS operator [watched]\u2013 there was a prime seat and a backup seat,\u201d Kennedy explained. \u201cSo that was the screen where the anomalous conditions came in, it was called the lookup.\u201d<\/p>\n<p>\u201cAs the lookups would display any anomalous condition you would be monitoring to say OK, that one voted good because we had two of the four that were good, and that one voted good because we had one of the three that were good. We had a lot of redundancy in Shuttle for protection of both the crew and the vehicle.\u201d<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-62286\" class=\"wp-image-62286 size-full\" src=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_.jpg\" alt=\"\" width=\"1535\" height=\"1023\" srcset=\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_.jpg 1535w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-350x233.jpg 350w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-525x350.jpg 525w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-768x512.jpg 768w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-1170x780.jpg 1170w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-585x390.jpg 585w, https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2019\/07\/S93E0397.crop_-263x175.jpg 263w\" sizes=\"(max-width: 1535px) 100vw, 1535px\"><\/p>\n<p id=\"caption-attachment-62286\" class=\"wp-caption-text\">Credit: NASA.<\/p>\n<p><em>(Photo Caption: Another image of the fully-loaded STS-93 Shuttle vehicle (Orbiter, External Tank, Solid Rocket Boosters) during the countdown for the first launch attempt taken by the Final Inspection Team on the evening of July 19, 1999.)<\/em><\/p>\n<p>The Orbiter\u2019s Redundant Set Launch Sequencer (RSLS), running on its four primary General Purpose Computers (GPC), is in charge of the last half minute of the countdown. Although the RSLS was now issuing commands and enforcing the Launch Commit Criteria, the GLS continues to monitor that criteria and is still issuing some commands.<\/p>\n<p>The automatic hand-off from GLS to RSLS occurs with the \u201cGo for Auto-Sequence Start\u201d milestone at T-31 seconds and the GLS operator announces that milestone on the voice loops and arms a manual cutoff capability. \u201cOnce we sent the \u2018go for auto-sequence start\u2019 to the on-board, the on-board actually launches the vehicle, so at that point, you\u2019re just monitoring.\u201d<\/p>\n<p>\u201cYou\u2019re working through T-31 seconds, you\u2019re prepared for a cutoff any time after that.\u201d Below the console displays was a programmable function panel, with several buttons. \u201cOnce the 31 second [milestone] comes through you arm the manual cutoff, so you would arm it with your left hand and then you would have your thumb on the button for the execute which would send the vehicle the stop.\u201d<\/p>\n<p>\u201cThe arm is on the top and the execute is on the right bottom,\u201d she noted. While the GLS and Columbia\u2019s computers are busy starting the Solid Rocket Booster (SRB) hydraulic power units (HPU), finishing configuration of the Main Propulsion System (MPS) for engine start, and continuing to verify all the criteria are being met, NASA Test Director (NTD) Doug Lyons made calls on the launch team voice loop as the countdown passed through twenty-five, twenty, fifteen, and ten seconds for an on-time liftoff at 12:36 am Eastern Daylight Time.<\/p>\n<p class=\"post-nav-links\">Pages: 1 2<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the span of a few seconds, a smooth countdown to launch Space Shuttle Mission STS-93, a five-person crew, and the Chandra X-Ray Observatory abruptly ended twenty years ago just before ignition of Orbiter Columbia\u2019s three Space Shuttle Main Engines (SSME). An indication that hydrogen gas was leaking into the orbiter\u2019s aft compartment where the [&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":[1785,8951],"class_list":["post-37969","post","type-post","status-publish","format-standard","hentry","category-news","tag-columbia","tag-sts-93"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/37969"}],"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=37969"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/37969\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=37969"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=37969"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=37969"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}