The final work on Kennedy Space Center\u2019s Pad 39B is being conducted in line with the construction and outfitting of systems on the Mobile Launcher (ML) for the Space Launch System (SLS). This multi-element verification and validation (V&V) testing is set to take place next year, a full dress rehearsal ahead of the rollout of the Exploration Mission-1 (EM-1) rocket.\n<\/p>\n
Pad 39B:<\/p>\n
In parallel with the work to outfit the Mobile Launcher, as outlined in an article earlier this week, construction efforts at Launch Pad 39B are also moving towards completion.<\/p>\n
Work to refurbish the pad flame trench was recently completed, which allowed installation and build up to start for the flame deflector and sound suppression water piping that sit below the launch vehicle and platform.<\/p>\n
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\u201cThe sound suppression pipe that you saw go in, that is part of the flame trench flame deflector construction project,\u201d Regina Spellman, GSDO Senior Project Manager for Launch Complex 39B explained in an interview with NASASpaceFlight.com.<\/p>\n
\u201cThat pipe has to go in first because of its size and the flame deflector gets constructed around it. They started erecting the flame deflector last week and in just the short ten days or so [of construction] it\u2019s incredible the amount of progress being made. It\u2019s actually starting to look like a deflector. The entire project should be finishing up this fall.\u201d<\/p>\n
This deflector will channel the launch vehicle exhaust in one direction \u2014 to the north. The SLS vehicle and tower will be situated at the pad similarly to the Saturn V, with the tower positioned on the north-side of the vehicle; the flame trench runs in a north-south direction under the launch platform.<\/p>\n
The approach with the new deflector is different from the Space Shuttle, where exhaust was channeled both to the north and south.<\/p>\n
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\u201cThe main reason is the rocket engine configuration,\u201d Spellman explained. \u201cIf you think about the tail end of the Space Shuttle \u2014 the External Tank, the SRBs \u2014 the engines and the rockets were staggered. If you envision in your mind an upside down V-shape [for the deflector], part of the engines were on the south side of the apex of that V and the other part were on the north side. For SLS, they are all in a line and so we\u2019re able to get it all on the same side of the deflector.\u201d<\/p>\n
\u201cAnd then it\u2019s also a lot more efficient from an operations and maintenance standpoint. The front face will have the surface that can withstand the exhaust blast, [but] the back side is just open structure, so we can get in there and maintain it much simpler. So it\u2019s optimized that way and because of the rocket configuration, them all being in a straight line it puts it all on the single side.\u201d<\/p>\n
The sound suppression water system fill will be fed with 400,000 gallons of water from the pad water tower. Spellman noted that they are planning on testing the different legs of the system before the launch vehicle gets to the pad.<\/p>\n
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\u201cOnce we\u2019re finished with the flame deflector and prior to the Mobile Launcher coming out, we\u2019re going to flow that water \u2014 because we have done some modifications to that system and we\u2019re putting in a new header underneath the deflector, we want to run water through that before the Mobile Launcher comes out there,\u201d she said.<\/p>\n
\u201c[When] the Mobile Launcher is going to be there, we\u2019re doing other testing, we\u2019ll also have some time [to] flow water then also through the Mobile Launcher leg of it.\u201d<\/p>\n
The flame deflector is one of the handful of big projects remaining at the pad.<\/p>\n
\u201cWe have three projects that are remaining of our large projects and then several small things that we have to finish up,\u201d Spellman added. \u201cThe flame trench flame deflector is one of those, the liquid hydrogen separator [is another]. That should be finishing up within the month.<\/p>\n
\u201cAnd then our third project is the environmental control system, and they are in system testing now, they\u2019re in a pre-testing phase just trying to run the system with the control software and then we\u2019ll get into operational simulations of that environmental control system.\u201d<\/p>\n
The addition of the separator to the hydrogen venting system at the pad was driven by differences between the Shuttle vehicle and SLS.<\/p>\n
\u201cDuring Shuttle, when they would drain off the hydrogen from the vehicle it would go to the flare stack and be burned off,\u201d Spellman explained. \u201cIt would warm up enough that when it got to the flare stack it would be in a gaseous state.<\/p>\n
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\u201cFor SLS, we are actually using hydrogen also for cooling of the engines. Because of the amount of hydrogen that we\u2019re using, when they drain it back the analysis has shown that it may not all be in gaseous form when it hits the flare stack and so the separator is kind of like an above ground septic tank, if you will, where it gathers the liquid and allows it to warm up.<\/p>\n
\u201cThen as it goes from liquid to gas it gets sent over to the flare stack to be burned off. And that way we\u2019re ensuring that we\u2019re not hitting that flare stack with liquid.\u201d<\/p>\n
Spellman also noted the additional consumption of hydrogen was one of the factors that drove starting the construction project for an additional liquid hydrogen sphere at Pad B, although it won\u2019t be required until the SLS Block 1B vehicle flies, which is planned for its debut on the second SLS launch.<\/p>\n
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Although not a construction project, another sign of the pad returning to operational status will be the refilling of the liquid oxygen and liquid hydrogen cryogenic spheres there.<\/p>\n
\u201cWe\u2019re going to fill them both at the same time,\u201d Spellman noted. \u201cWe\u2019re going to start hopefully sometime in the September time-frame and it\u2019ll take about six months to get both of them completely full. The reason it takes so long is one, just the quantity that is required \u2014 both of them are almost 900000 gallons and we fill them with tankers.<\/p>\n
\u201cWe have a wave of tankers come in and fill these, so it takes time just to accumulate that amount or quantity and also because all of the steel structure is at ambient temperature, which right now in Florida is pretty hot. So we fill them with the cryogenics and we start to cool down the structure.<\/p>\n
\u201cA lot of that initial wave of tankers are really just going to boil off while the structure is coming down to temperature and then we\u2019ll start to accumulate. It takes a while to accumulate that amount of commodity.\u201d<\/p>\n
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Those waves of tankers will continue to make regular visits to replenish boiloff of the commodities, and given that the first launch has slipped into 2019, NASA has waited to start the process.<\/p>\n
\u201cThat\u2019s one of the reasons why we have delayed filling them in addition to having the construction that is going on out there in the hazardous environment that the cryogenics that would create,\u201d Spellman explained. \u201cWe don\u2019t want them sitting and just boiling off and just continuing to replenish them. We\u2019ve been down for about ten years, and so it was efficient to just drain them and bring them back up. Once they\u2019re full prior to the first launch we will continue to just top them off.\u201d<\/p>\n
Spellman also noted that both spheres went through refurbishment while they were drained.<\/p>\n
\u201cBoth of them have been refurbished and repainted and just basic corrosion control of the spheres themselves,\u201d she said. \u201cWe did top off the Perlite \u2014 the sphere actually has an inner sphere inside of it and the annular space between the two spheres has an insulating material called Perlite.<\/p>\n
\u201cTowards the end of the Shuttle program there were signs where that Perlite had settled and so there was kind of a hot spot where it was boiling off a little quicker. We have gone in and topped that off to get it back to expected performance.\u201d<\/p>\n
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The current forecast shows that the Mobile Launcher will be ready to move into substantial integrated testing first in the VAB and then out at Pad 39B early next year. Crawler Transporter 2 will pick it up and transport the ML to the pad first for some fit checks.<\/p>\n
\u201cFirst we\u2019ll leave the park site where we\u2019re doing construction and we\u2019ll head to the pad for\u2026probably a week to do some mechanical fit checks,\u201d Cliff Lanham, GSDO Senior Project Manager for the Mobile Launcher said. \u201cThen from there, we\u2019ll roll into the VAB \u2014 that\u2019s probably in the mid-January time-frame.<\/p>\n
We\u2019ll spend roughly until mid-May doing multi-element testing with the VAB, and we\u2019ll roll to the pad in May and plan to finish up in September of 2018 with our multi-element pad testing.\u201d<\/p>\n
(Images via NASA and L2 SLS Sections \u2013 the latter including a master LETF and ML Update Section full of images and videos from the test sites. To join L2, click here: \/\/www.nasaspaceflight.com\/l2\/)<\/p>\n","protected":false},"excerpt":{"rendered":"
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