Boeing expanding SLS Core Stage production to KSC to build Artemis inventory

by Philip Sloss

Boeing, the prime contractor for NASA’s Space Launch System (SLS) Core Stage, is adding two new work locations at the agency’s Kennedy Space Center (KSC) in Florida as the company looks to support increases in the production rate of the launch vehicle. The completed engine section structure for the third Core Stage is being transported by barge from NASA’s Michoud Assembly Facility (MAF) in New Orleans to KSC, where Boeing will now outfit the most complicated element of the SLS inside the Space Station Processing Facility (SSPF).

After the rest of the third Core Stage unit is completed at Michoud, it will also be barged to KSC, where final assembly will be moving into High Bay 2 of the Vehicle Assembly Building (VAB) at KSC. The large volume of the VAB High Bay will allow Boeing to store completed Core Stages without interfering with continuing production, which frees up more space at Michoud to expand operations there for production of the new Exploration Upper Stage (EUS) for the next generation of the SLS vehicle.

Establishing KSC Worksites to Expand Overall Production

The initial goal for the SLS program is to reach a flight rate of one launch per year, but NASA and its prime contractors for the vehicle studied for a long time how to increase the production of its boosters, engines, and stages to reach higher flight rates. Boeing’s expansion of Core Stage production to Florida was born out of those continuing discussions.

“NASA had asked us to do some studies on developing a process to deliver one and a half cores per year or three every two years and also up to two per year,” John Shannon, Boeing’s Vice President and Program Manager for SLS, said in a Dec. 6 interview with NASASpaceflight. “Operations at MAF [are] going extremely well. We learned a lot about how to assemble the vehicle, what it takes during the Core Stage-1 and now Core Stage-2 builds.”

SLS successfully completed its first launch on Nov. 16, sending NASA’s human-rated Orion spacecraft on the Artemis I mission to orbit the Moon. The Block 1 configuration of the vehicle, which launched Artemis I, uses a modified version of United Launch Alliance’s Delta IV upper stage; however, NASA and Boeing are developing an in-house upgrade called the Exploration Upper Stage (EUS), which is also being manufactured and assembled at Michoud.

The Core Stage-3 engine section structure being loaded on the Pegasus barge at MAF on Dec 4. (Credit: NASA/Michael DeMocker)

The Block 1B vehicle will combine EUS with the Core Stage and Boosters to increase trans-lunar payload performance from 27 metric tons to at least 38. Boeing had to factor in the overlapping, multi-phase production of both stages when considering how to increase delivery rates. “We did facility studies, and with the addition of the entire Exploration Upper Stage set of tooling and assembly processes, it is really tight in the factory to be able to get two Core Stages out per year,” Shannon said. “So we started looking around [at] our options.”

Shannon said that building new facilities at Michoud was feasible but “pricey.” “We also wanted to reduce the overall cost of the rocket — we’ve been working on affordability a lot, so we kind of turned our eyes to KSC because there’s some really top-flight facilities that were being underused or not used at all,” he noted.

“I was familiar with them from time in the [Space] Shuttle program and the ISS (International Space Station) program, and so we started talking to KSC, and we worked out an opportunity for us to start using the Space Station Processing Facility (SSPF),” Shannon explained. Shannon was Program Manager for both programs, serving as NASA’s Program Manager for the Space Shuttle at the end of the program and as Boeing’s ISS Program Manager before managing Boeing’s SLS Program.

Beginning with Core Stage-3, Boeing is moving the outfitting and integration of all the Main Propulsion System (MPS) equipment inside the engine section structure to the clean room environment at the SSPF. In addition, they will stack completed engine sections with the rest of the stage in VAB High Bay 2 after it is completed at Michoud and transported to Florida.

“We looked at [the KSC expansion plan] a little more and said that we’re also going to need a place to store Core Stages, and we looked at the VAB,” Shannon said. “High Bay 2 hasn’t been used in a very long time, so we made a proposal to NASA to go do some demolition in High Bay 2, upgrade the crane, and build some pedestals in there.”

Shannon explained that Boeing will use the space in High Bay 2 in two ways. “One is to store finished Core Stages in High Bay 2, and the other one is the ability to take [the other] four-fifths of the rocket and mate it to an engine section,” he said.

The other four of the five major elements of the Core Stage are, from top to bottom, the forward skirt, the liquid oxygen (LOX) tank, the intertank, and the liquid hydrogen (LH2) tank. Current production at MAF assembles and outfits those four elements separately first and then joins them together into a “four-fifths” assembly; when the engine section is completed, it is mated to the bottom of the LH2 tank to begin the final phase of overall stage assembly.

“So we said if we can bring down some engine sections, do some integration in the SSPF, and then bring down the 4/5ths that’s completed from Michoud, then we can do the stacking inside of the VAB High Bay 2 and really shorten our production time,” Shannon pointed out. Boeing estimates both per-unit cost-savings and an increase in production rate.

“We’re estimating around 50 million dollars [of savings] per Core, and we can do more than two Core Stages per year by utilizing the additional facilities,” Shannon said.

Credit: NASA/Jude Guidry.

(Photo Caption: NASA Administrator Jim Bridenstine looks at the Artemis I engine section when it was in production at MAF in August 2018. He is looking through the top of the clean-room environmental enclosure that has to be set up and broken down during integration at MAF. In the SSPF at KSC, the entire high bay is maintained at a 100k cleanliness level, which should eliminate the need to build up and break down smaller enclosures around different parts of the engine section.)

He noted that Boeing took the results of this study and their recommendations to NASA and their other stakeholders earlier in the year. “We had proposed it to NASA over the summertime [and] said this is really the only way we can get to a two-plus a year [production] rate,” Shannon said.

“We asked to get the ability to get into High Bay 2, so Boeing said we’ll take on the cost of doing the mods to the high bay. The SSPF we really didn’t have to do mods to, but we showed NASA that this is a better way to reduce the cost of the vehicle by reducing production time significantly. We’re in a mode of trying to save costs now that we understand how to produce the vehicle, so NASA was all on board with doing that.”

Shannon said that Boeing also consulted with their stakeholders in Louisiana about the impact of the proposed changes at Michoud. “We explained to them that this isn’t taking any jobs out of Louisiana, it is actually increasing the production rate at Michoud, along with giving us the space to do the upper stage work, so we’re going to end up hiring more people there, so they were happy with it, as well,” he said.

“It made sense all the way around, and then it was just making sure that we had all of our logistics covered to be able to ship engine sections and get the parts there and be able to hire up the right team to be able to do the assembly. For the long-term health of the program, this is a very positive move.”

Engine Section Integration in SSPF

Work to outfit engine sections with all their internal equipment and most of their external thermal protection system (TPS) is already in the process of moving to the Space Station Processing Facility at KSC. Structural assembly of engine sections will continue at MAF in New Orleans, where all of the friction-stir welding and bolted-assembly tools are in place.

The engine section structure of the element consists of a welded barrel, a welded mating ring, and a bolted thrust structure; the barrel and ring are then bolted to the thrust structure in a floor assembly jig (FAJ) at MAF. Thousands of bolts structurally integrate the barrel and the thrust structure while it’s in the jig, and some secondary structures like brackets to hold electrical wiring and other equipment are also added during this phase of assembly.

The Core Stage-3 engine section has completed its structural assembly at MAF, and on Dec. 4,  the structure was rolled out of the rocket factory in New Orleans and onto NASA’s Pegasus barge docked at Michoud to be transported to KSC. “[The engine section] is not shipped with the boattail on it, but it is shipped with all the major structures in it and the thrust structure installed, so from a structural build standpoint, it’s as far as we can go at MAF,” Shannon said. “When we would normally get into a clean room environment, that’s when we ship it to KSC for integration.”

Credit: NASA/Glenn Benson.

(Photo Caption: The Artemis I Orion Stage Adapter is received in the Space Station Processing Facility in April 2018. Boeing has allocated two of the eight large work area “footprints” on the SSPF high bay floor for Core Stage engine section integration work. The Core Stage-3 engine section will be positioned in Area 5, which is located on the right where the large American flag is. Area 7 is adjacent and behind that area on the right; work on the Core Stage-4 engine section will begin there next year after it is transported to KSC.)

The SSPF high bay is a large clean room area for processing spaceflight equipment, which made it very appealing as a location to expand engine section production. “It’s a huge facility that is a ‘100K’ clean room, and it has an airlock in the front of it where you bring large pieces there, clean them, and then you can take them into this clean room,” Shannon explained. “We started thinking about that and realized that if we could do some of our final engine section integration work there, then we would alleviate ourselves from having to build all of the clean areas and the areas that are all shrouded by plastic and such that we have the purges going in, which saves a huge amount of time.”

During the outfitting/integration of the first two Core Stage engine sections at MAF, the clean area enclosures were set up right around the flight hardware and would need to be broken down and then rebuilt to allow MPS equipment to be “flown” inside — lifted and lowered inside by crane. A large cover with the same 8.4-meter diameter as the engine section sealed the top of the clean area.

“We’ve got that big shower cap over the top, and every time that we fly any hardware into the engine section, we take that cap off, and then we fly [the MPS hardware] in there, and then we put the cap back on, and then we’ve got to go through the purge cycle to get it back to a clean room environment,” Shannon said. “You don’t have to do any of that [in the SSPF] at KSC; once it comes through that airlock, it is in a clean room environment, and you’re able to do all of assembly and all of your work — you’re not waiting around for the purge system to do its thing.”

Once Pegasus arrives at the KSC Turn Basin, Shannon said the structure will be rolled off the barge and rolled down the road to the SSPF: “We’ll offload it, clean it in the airlock [at the SSPF], and set it up in the tooling that is set up inside the SSPF and get to work on it.”

The engine section for Core Stage-3 is the first to be integrated at KSC, but Boeing has reserved floor space in the SSPF high bay for simultaneous work on a second one beginning next year with the engine section structure for Core Stage-4. “The floor is marked out into eight big rectangles,” Shannon said. “Right now, we’ve got rectangle number five to put all of our tooling, and we’ve got the team with their computers doing ship-side support, and they fill up that area pretty well. We can also do some offline work on some subcomponents that we fly into the engine section.”

“And then next July, we’re going to have section seven, which is the farthest back rectangle on the right-hand side if you’re looking at the back wall. So five and seven will be side-by-side, so we’ll have engine section three and engine section four being built at the same time back there.”

The engine section, where the powerheads of the four RS-25 engines and all the supporting MPS equipment come together, is the most complicated element of the SLS vehicle as a whole and the Core Stage specifically. At KSC, all of the wire harness runs for the electronics will be laid out and eventually interconnected. All of the pneumatic, hydraulic, and cryogenic tubing will also be welded and bolted together, along with the installation of instrumentation and avionics.

Later in integration offline subassemblies like the four thrust vector control (TVC) platforms that carry the hydraulic systems equipment and the five large helium composite overwrapped pressure vessel (COPV) bottles for the MPS pneumatic system will be “flown” by cranes into the engine section for installation. The engine section will go through a standalone functional test and then, when it’s ready to be mated to the rest of the Core Stage, it will be covered up, rolled out of the SSPF, and driven up the road to VAB High Bay 2.

VAB High Bay 2 Has Room for Core Stage Storage and Vertical Stacking

While the first engine section integration will begin in the SSPF, Boeing will also be working to outfit and configure VAB High Bay 2 for final assembly of a full Core Stage and storage of another. High Bay 2 was maintained as a “hurricane shelter” storage location for a completed Space Shuttle stack over the last decade of the program; after Shuttle was retired, NASA leased the high bay to Northrop Grumman for launch integration of its OmegA commercial launch vehicle.

Cancellation of the OmegA program in 2020 left the high bay again open for a commercial partner, and Boeing is now beginning work to turn it into a final assembly and storage area for SLS Core Stages.

Credits: NASA/Bill White (left) and Kim Shiflett (right).

(Photo Caption: VAB High Bay 2 as seen in 2017 and 2019. Two of the Space Shuttle External Tank checkout and storage cells can be seen on the left-hand, north wall of the high bay. Boeing is planning to convert some of that infrastructure into a storage cell for completed Core Stages. A processing cell to support final assembly of another Core Stage will be created on the right-hand, south wall. Boeing will also be refurbishing the yellow, 325-ton crane that services High Bays 1 and 2 which can be seen on the far left attached to a proof load fixture.)

During the Space Shuttle program, NASA had four storage/checkout cells for External Tanks (ET) adjoining the tower structure between VAB High Bays 2 and 4, Tower B. Each of the four high bays is flanked by towers; High Bay 2 has Tower B on its north wall and Tower A on its south wall. Shannon said that some of the checkout cell infrastructure will be retained on the north Tower B side for storing one Core Stage, but Boeing will also develop final assembly processing cell on the south Tower A side.

“The diameter obviously is the same between the stages and the ET, so we’re going to leave some of the platforms in,” he said. “There was an old [Mobile Launch Platform] that we’re going to end up [demolishing], we’re going to have to fix up the crane, and we’re going to have to build a pedestal.”

“For the most part, it’s not a huge amount of work; we’ll use both the north wall and the south wall of High Bay 2 to fit two Core Stages in there. We’ll use existing platforms and build scaffolding off of that to get access, and we’ll have a really nice place to store our Core Stages kind of out of [the] way in the VAB but also where we can work on them and get them prepped up to be moved over to High Bay 3 when needed.”

Boeing spokesperson Megan Gessner noted in an email: “Core Stage 3+ processing will be on the A tower side and consist of a base pedestal system and multiple platforms to access the vehicle internally and externally. An additional pedestal stand will be emplaced on the Tower B side and have the capability to stand up a Core Stage vertically.”

“This Tower B side will provide access to the engine section volume and partial access to other volumes internally and externally via various levels of existing ET check-out cell platforms,” Gessner added.

Boeing will be working with a frequent partner, Futuramic, on the new tooling to support both vertical storage and final assembly of Core Stages. Shannon was planning to begin discussions with them soon: “I’m going to thank [Futuramic] for all their support to Artemis I first, and then we’re going to go through the design of the pedestals and tooling,” he said.

Boeing hopes to have an initial set of tooling by the middle of 2023. “The (demolition) contracts have been let, and I think that work will be starting pretty soon,” Shannon added.

Credit: Philip Sloss for NSF.

(Photo Caption: Placard as seen entering the VAB in 2012. Boeing will outfit a storage cell for a completed Core Stage on the north Tower B side of High Bay 2 and a processing cell for finishing assembly of Core Stage elements on the south Tower A side.)

The initial use of the tooling could be as early as the third quarter of 2023, demonstrating the vertical storage capabilities of VAB High Bay 2. Work continues at Michoud on hardware for the next three cores, including the completion of Core Stage-2 in the first half of 2023.

“We’re finishing our final testing on the engine section; we’ll rotate it right after Christmas,” Shannon said. “You take it over to the Building 110 area, [and] you add the big weights on it to counter-balance it.”

After the engine section is rotated from its vertical orientation with its counter-balancing structure attached to horizontal, it will be brought back to the final assembly area at MAF and mated to the rest of Core Stage-2. “We’ll rotate it, bring it back over, and [after mating it to the rest of the stage] do checkouts, engine installs, and all the final TPS work on it, and then first half of next year we’ll be rolling Core Stage 2 out,” Shannon said.

“That’s well ahead of the need date for Artemis II for other reasons, and so we’ll take it to KSC and it’ll be in the [VAB] Transfer Aisle for some series of months.” While it might be possible to store the completed second Core Stage that will be used on the Artemis II mission, there aren’t many places even at the large facilities at Michoud to put it without interfering with the ongoing work on hardware for the third and fourth builds.

“It’s a good problem to have, but we realize there’s some pinch points in the factory flow [at Michoud] to have multiple, almost full-size, 212-foot vehicles maneuvering around, and so this is really going to help us,” Shannon noted. Even within the large confines of the VAB, storing Core Stage-2 on its side in the Transfer Aisle takes up a lot of floor space; once the VAB crane for High Bay 2 is upgraded and the new tooling is ready, the plan is to lift the stage, rotate it to vertical, and put it in the new storage cell on the north wall of the high bay.

“We’ll do some work in the Transfer Aisle [on Core Stage-2], but then we’ll stand it up in High Bay 2 and finish every bit of work that has to be done on it,” Shannon said. “So when we lift the Core Stage over to High Bay 3 and we mate it to the Boosters [for Artemis II], it is a completely finished, ready-to-go Core Stage, and we don’t have to do some of the work that we had to do on Artemis I’s vehicle.”

Credit: NASA/Michael DeMocker.

(Photo Caption: The Core Stage-3 engine section structure is moved at MAF on Nov. 7 to be prepared for shipment to KSC. In the background, the structure of the Core Stage-4 engine section is seen in a floor assembly jig, where the barrel, ring, and thrust structure are being bolted together.  That unit could be shipped to KSC as soon as next July to begin its integration.)

Depending on the availability of the new storage cell and the integration schedule for Artemis II, Core Stage-2 could be in storage vertically in VAB High Bay 2 for a few months or longer. To increase Core Stage production beyond the one unit needed for the initial flight rate, Boeing is looking to build a small inventory of these large rocket stages in the VAB for NASA’s Artemis launch schedule.

“We want to get ahead by a couple of Cores from the manifest, and I think probably by the Artemis V or VI time frame, we’ll be able to do that,” Shannon said.

Workforce Hiring at MAF and KSC to Support Production Expansion

The addition of a second Core Stage production site at KSC will require an increase in the workforce at both locations. “We’re really not impacting the workforce at MAF; we’re actually staffing up there because when you do this, it enables you to get more vehicles in flow, and if you have more vehicles in flow, you need a larger workforce to do that at Michoud,” Shannon said.

Michoud will still be completely assembling and mating the other four major Core Stage elements, and Boeing is adding the entire EUS production cycle to that work. “The plan right now is to finish four-fifths of the rockets completely [and] also to finish the EUS completely before we ship [them] of [Michoud],” Shannon said.

“And I would even say there’s the potential down the road that we’ll have two engine sections in work at the SSPF and two engine sections in work at Michoud if we have a way to jockey the space around to support that, but right now we think just from a floor space use standpoint that would be a little more difficult to do.”

Shannon also noted that the Michoud workforce in New Orleans plans to stay. “There are very few people that work at MAF that are moving to Kennedy Space Center,” he said. “Most of the people working at MAF like working at MAF. We’ve really tried to focus on hiring local talent in Louisiana. That’s where they’re from, where they like to work, so they’re staying.”

As Boeing transitions from design to initial production of EUS flight and test hardware for its first flight, they are looking ahead to having both the liquid stages for the Block 1B vehicle in full production at the same time. “We’re increasing the number of people at MAF by about 125 people, and that’s to support the additional vehicles that we’ve got under flow and also to do the Exploration Upper Stage work, so they’re fully staffed and going up a little bit,” Shannon said.

Credit: NASA/Eric Bordelon.

(Photo Caption: The top “four-fifths” of Core Stage-2 are seen after they were joined in March; from left/aft to right/forward are the LH2 tank, intertank, LOX tank, and forward skirt. Boeing will continue to fully outfit the four elements individually and then bolt and connect them at MAF. Beginning with Core Stage-3, the “four-fifths” assemblies will then be shipped to KSC where they will be attached to engine sections in the VAB.)

Boeing already has a large presence on the Space Coast, with the headquarters of its Space and Launch Division in Titusville, Florida; the workforce at KSC will also expand. “We had a pretty good Boeing footprint down there supporting other vehicles, like Commercial Crew [Starliner] or X-37; they’re available to us, and we’re also hiring people,” Shannon said.

Shannon also noted that they had added people in Florida to support the effort to launch Artemis I, and they could also be a part of the new Core Stage work at KSC on the engine sections in the SSPF and the full stages in the VAB. “It’s really about 145 at KSC for what we have [planned] now, and that would go up a little bit once we get Core Stage 4’s engine section there,” he said. “But right now, our target is about 145 people.”

In terms of logistics and support, Boeing will move existing tooling to KSC, but Michoud will remain central to the logistics supply chain. “We’re still kitting the parts at Michoud, so we’re not changing where the suppliers send the hardware,” Shannon said. “We have a pretty intricate and mature system for kitting the different pieces at Michoud, and then we send them by truck to Kennedy, where they’re inspected before they go into the SSPF and then get installed.”

“We’ve modified a building at KSC where we can take [support] hardware in, do the inspections, and then get it over to the SSPF.”

(Lead image: The Core Stage engine section for Artemis III on board Pegasus for transport to KSC. Credit: NASA)

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