EGS, Jacobs begin SLS booster build up for Artemis 1

by Philip Sloss

“There is some ordnance lines, some firing lines, that we install and checkout over in the Rotation building,” he explained. “That’s the separation ordnance for the three struts that we have on the [Core Stage Attach] ring.”

There is also some ground test instrumentation that needs to be installed on this first SLS vehicle for more pre-launch development tests. “We also have modal sensors that we will install on the aft motors; we do that in the build up stand,” Angermeier said.

“When we’re in the VAB we have the Integrated Modal Test that we have to do for the full vehicle. We have ninety-one sensors that we have to install on the two boosters while the booster segments are in the Rotation building, and so for the ones that we have to install on the aft motor, we do that in the build up stand.”

“And basically we have a series of closeouts on the [Core Stage Attach] ring and other parts of that booster assembly,” he noted. “Once we’re done with the fully integrated aft booster assembly, we’ll keep that in the build up stands until we need those over in the VAB once we commit to stacking.”

“So when we need them over in the VAB, we’ll lift it out of the build up stand, we will put it on a transportation pallet, and then we’ll use one of our transporters to take it over to the VAB, and we’ll commit to stacking.”

Credits: NASA/Kim Shiflett.

(Photo Caption: A composite of images from the start of right-hand aft segment lifting operations on June 24. After being set on the inspection stand pedestals, a lifting ring was disconnected from the aft end of the segment to prepare for the mate with the aft skirt. The segment was then lifted by one of the overhead cranes still attached to the forward lifting ring off the pedestals and into the build up stand for mating to the right-hand aft skirt.)

After both aft segments are offloaded from their railcars and installed in the build up stands in the Rotation/Processing Building, the rest of the segments will be brought to the building for offloading. “All the other segments, they come off the railcar and they go over to that pedestal like I mentioned before,” Angermeier said. “There’s a few operations that we do on the pedestal, and then we lift it and put the segment on top of a pallet that’s in what we call one of two inspection stands.”

Center and forward segments will be stored in the nearby Surge buildings of the RPSF until it is their turn for stacking in the VAB.

Stacking flight hardware on the Mobile Launcher will not begin until completion of the Core Stage test-firing at the end of the ongoing Green Run test campaign.

Spaceport facility sharing

The train carrying the 10 Artemis 1 live solid rocket motor segments from Promontory to KSC also included cars with two inert motor segments for the commercial OmegA launcher under development by Northrop Grumman. The company is planning OmegA’s first launch next year, and launch operations share multiple Launch Complex 39 facilities that EGS uses for SLS launch operations.

“One thing we’ve been working on within our program and with [KSC is] doing everything we can to make it a multi-user spaceport. And there is a lot of activity as you can see with SpaceX and their activities out at Pad A and then with Northrop Grumman and their OmegA rocket,” Angermeier said.

OmegA includes segmented solid rocket motor stages at its base. As with the SLS Boosters, they will be received and processed in the RPSF following rail transportation from the same Utah production facilities.

“The thing that we work with Northrop Grumman is a shared use of the facilities; it really comes down to when do the two programs need flight hardware elements processed and ready for use,” Angermeier said. “The facilities that they’re utilizing are managed by the Exploration Ground Systems program, the program that I work for.”

“We have daily integration meetings and they are part of those meetings and we do everything we can to make sure that the two programs can co-exist and not create any schedule impacts for either program. We worked with Northrop Grumman to understand their schedule and when they need those segments offloaded.”

Credit: NASA/Ben Smegelsky.

(Photo Caption: Jacobs personnel stand under the left-hand aft skirt in one of two build-up stands in the RPSF on June 23. Surrounded by an environmental enclosure, the inside of the aft skirt houses thrust vector control (TVC) components from hydraulic actuators to hydraulic power units to avionics boxes. Both aft booster assemblies will be integrated side-by-side in the RPSF build up stands this Summer.)

“It turns out that the timing when they need those is after we offload all the Artemis 1 segments. And so in our schedule right now we plan to get all the segments offloaded for Artemis 1 in the August time-frame, and then once we’re done with those in mid- to late-August, that’s the tentative schedule to offload the OmegA segments,” he said.

As with SLS launch processing, OmegA motor segments will be stacked on a separate mobile launcher in the VAB. EGS will integrate SLS vehicles in the northeast High Bay 3 cell of the VAB while Northrop Grumman will integrate OmegA vehicles in the southwest High Bay 2 cell.

As with the RPSF, the two programs will also synchronize operations and share ground support equipment in the VAB. “It’s a lot of integration,” Angermeier said. “We do have five major cranes in the building, but you can only have one major lift going on at a time in the building.”

“Whenever you lift a segment that’s not inert, a segment that has propellant in it, you have to clear the entire building. We have worked with Safety and there will be some operations that we may be able to do in parallel in the Vehicle Assembly Building while we’re lifting the segments. But generally speaking, we could not be lifting an Artemis 1 booster segment while they are lifting an OmegA segment up into High Bay 2.”

Stacking starts with the aft assemblies

While waiting to stack the flight hardware on Mobile Launcher-1 in VAB High Bay 3, EGS and Jacobs will run through one more practice session with inert motor hardware. Over the past two years, segment-to-segment mating exercises were performed “offline” in VAB High Bay 4, where SLS motor segments will go for final preparations to be lifted into the integration cell.

During previous practice periods, Mobile Launcher-1 was still under construction and going through checkout activities in and around the VAB; EGS and Jacobs will now get a chance to run through stacking procedures with the ML in High Bay 3. “Right now we have it tentatively set for early-August,” Angermeier said. “We have about two weeks of operations practicing stacking.”

“They have been practicing a lot of the joint mating activities offline in High Bay 4 with one of the stands that we have over there. Our plan to stack it on the ML is we will stack the aft motor inert and then we’ll stack an inert center segment on top of that.”

“Then we’ll destack that inert center segment, lift the aft motor assembly off one set of support posts and put it on the other one and then we’ll stack the inert center on top of that one again. So basically we’re going to work on both Vehicle Support Posts (VSP) with the [inert] aft booster, so we’ll get a chance to essentially mate that first joint twice up on the ML in August.”

Following roll on a transportation pallet from the RPSF to the VAB, most segments will go through a similar sequence of final stacking preparations in High Bay 4. “For the non-aft segments, we have to place it over the slap stand, and we do our operations to ensure that the lower part of that segment (tang) from a roundness perspective is going to fit nicely with the clevis part on the segment that’s already up in the High Bay,” Angermeier said.

Credit: NASA/Glenn Benson.

(Photo Caption: NASA EGS and Jacobs technicians practice segment lifting and field joint mating operations with inert hardware in VAB High Bay 4 in January. On the left, an inert center segment is lifted to practice mating its bottom, clevis end to the top, tang end of an empty, bare metal segment case. On the right, another bare metal cylinder is mated to an inert aft assembly in one of the build up stands used early in the Shuttle program. The inert aft assembly and inert center segment will be used to practice stacking and mating operations on Mobile Launcher-1 in High Bay 3 later in the Summer.)

“So we lift off the pallet, we position over what we call the slap stand, we do the inspection of the lower mating joint. We do the alignment [check], and then once we get the go from engineering that we have good alignment between the clevis and the tang, we will lift and go up and over and commence the mating operation over in High Bay 3.”

“For the [aft] segments they will just roll into the center part of High Bay 4, we’ll attach the 384-beam and we’ll go up and over.”

In contrast to when they were used on Shuttle SRBs, the aft booster assemblies will not be held down for launch. “With Shuttle what we had is a system where the nut was pyrotechnically split in two and then the bolt would fall into our hold down post and then the nut would fly with the boosters and then we would get it post-flight,” Angermeier explained.

“We do not have that on Artemis rockets, so when we stack it there’s no bolts that we attach to the support post and the aft skirt.” Non-pyrotechnic, non “T-zero” bolts will be used temporarily when the fully integrated vehicle is moved by a Crawler Transporter during rollout to the pad and rollback from the pad to the VAB.

“Prior to roll for Wet Dress, we clamp the boosters to the VSP using a nut/bolt similar to what we used in shuttle, eight total,” he explained. “When we get to the pad for Wet Dress, we will remove the bolts to rehearse what we will do following the launch rollout.”

“We will reinstall the bolts prior to rollback following WDR, and they will stay installed until we rollout for launch. They will be removed days prior to launch when we are at the pad. The boosters are heavy enough that we won’t have to worry about them moving around without bolts installed.”

Following roll on a transportation pallet from the RPSF to the VAB, most segments will go through a similar sequence of final stacking preparations in High Bay 4. “For the non-aft segments we have to place it over the slap stand and we do our operations to ensure that the lower part of that segment (tang) from a roundness perspective is going to fit nicely with the clevis part on the segment that’s already up in the High Bay,” Angermeier said.

“So we lift off the pallet, we position over what we call the slap stand, we do the inspection of the lower mating joint. We do the alignment [check] and then once we get the go from engineering that we have good alignment between the clevis and the tang and we will lift and go up and over and commence the mating operation over in High Bay 3.”

“For the [aft] segments they will just roll into the center part of High Bay 4, we’ll attach the 384-beam and we’ll go up and over.”

Lead images credit: NASA/Kim Shiflett.

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