NASA EGS, Jacobs preparing SLS Core Stage for Artemis 1 stacking - NASASpaceFlight.com - NASASpaceflight.com

April 21, 2021.

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The Core Stage of NASA’s first Space Launch System (SLS) vehicle arrived at the Kennedy Space Center (KSC) and was moved into the Vehicle Assembly Building (VAB) on April 29.

The stage is now in the low bay of the VAB, where some “traveled” work from the recently-completed Green Run design verification campaign will be performed in parallel with preparations for stacking with the new launch vehicle’s Solid Rocket Boosters (SRB), which are already in place on the Mobile Launcher in VAB High Bay 3.

First, Core Stage prime contractor Boeing completed the Green Run design verification campaign on the first flight article, Core Stage-1, at the Stennis Space Center in Mississippi.

Just before arrival, the SLS Core Stage team completed the Element Acceptance Review (EAR) for Core Stage-1 on April 26.

The next major milestone is to get the stage mated to the SLS Boosters, which are assembled on Mobile Launcher-1 in the High Bay 3 integration cell of the VAB.

Mating the Core Stage to the Boosters is the next big, highly visible milestone, but moving the stage into launch position also opens up major job paths that EGS and Jacobs can then work on simultaneously.

“There’s a lot of parallel work that’s going to be happening once we stack and get the Core Stage mated to the Boosters.”.

The stage is still resting in its Multi-Purpose Transportation System (MPTS) carrier, where the remainder of the work while it is horizontal will be done.

The major job originally planned while the stage was horizontal in the VAB Transfer Aisle was installation of the components of the Flight Termination System (FTS).

The FTS assemblies will be installed inside the systems tunnel of the Core Stage, which runs almost the entire length of the element along its exterior

The work was planned for this point in the processing flow because there is better access to the tunnel and the work area now while the stage is horizontal

With the additional traveled work from Stennis, the current forecast for mating the Core Stage to the Boosters is the end of May, beginning of June

Some of the refurbishment of the Core Stage thermal protection system (TPS) was moved to the KSC task list while it is still horizontal

Similar to the work deferred from Stennis, any refurbishment work that doesn’t need to be done while the stage is horizontal will be deferred to later in the launch processing flow; however, there are some TPS inspections and repairs that need to be done now

In the top middle of the images are two dark areas around the intertank to LH2 tank flange where the spray-on foam insulation (SOFI) closeouts need to be repaired. In addition, the plan is to repair areas of the Core Stage TPS while the stage is in its current horizontal orientation, especially areas that would be inaccessible after it is stacked vertically with the SLS Boosters.)

There are areas around the outside of the stage that are easier to access right now than they will be after it is mated to the two boosters

In particular, after the boosters are attached, they will physically restrict access to external areas on the sides of the Core Stage

The boosters will block the 90 and 270 degree locations around the 360-degree circumference of the stage, so any repair locations that would be made hard or harder to reach would be candidates to tackle now

The flanges are where the five major structural elements of the Core Stage are bolted together during assembly

(Photo Caption: A graphic showing the SLS vehicle configuration with the different points around the circumference of the Core Stage. The Boosters attach at the 90 and 270 degree locations; TPS repair work in those areas is being prioritized since they will be inaccessible after the Boosters and Core are mated.)

The more visible TPS damage seen during the two static test-firings was to the bottom of the stage on its base heatshield, but that traveled work can be scheduled for later in the processing flow in parallel with the critical path processing of the assembled SLS vehicle

“We should have very good access to the base heat shield after the Core Stage is vertical and integrated with the boosters in HB-3,” Alldredge noted

The SLS Core Stage was the final major Artemis 1 component to arrive at KSC, which will enable EGS and Jacobs to complete launch preparations

The Core Stage Green Run Hot-Fire that was completed on March 18 at the Stennis Space Center was the final major standalone development test

The four engines in the Core Stage are returning to KSC for the first time in almost a decade after being stored at Stennis Space Center for several years

Once the work in the low-bay transfer aisle is completed, the self-propelled motorized transporters (SPMT) will again pick up the MPTS carrier with the Core Stage on board and roll them into the north transfer aisle between the VAB’s high bays, where the stage will be prepared for the lift “up and over” into High Bay 3 for mating to the Boosters

The unit at Stennis was disconnected from the Core Stage before it was rolled onto the barge and after it had been rotated or “broken over” from vertical to horizontal

The second unit was delivered to KSC when the Core Stage Pathfinder stopped through in 2019 for shipping and handling practice, and will again be used to take the Core Stage back to a vertical orientation for attachment to the SLS Boosters

The first piece is the Transportation Interface Fixture (TIF) that will be used to hold the 45,000-pound, yellow-painted spider while it is moved into place and bolted to the top end of the stage

One of the two 325-ton cranes will be attached to the spider on the front of the Core Stage, and the 175-ton crane will be attached to lift points on the engine section structure

And then after they level [the Core Stage] with the master link which is connected to the spider, they then fly it up and be able to lower it down and mate it to the Boosters.”