NASA SLS core/booster mate sets the stage for Artemis 1 pre-launch checkout - NASASpaceFlight.com - NASASpaceflight.com

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The integrated operations team of NASA’s Exploration Ground Systems (EGS) and prime launch processing contractor Jacobs completed mating the SLS Core Stage for Artemis 1 with its boosters on June 13, another in a series of firsts that will culminate in the debut flight of NASA’s new launch vehicle, currently projected for no earlier than late-2021.

After the stage was raised off its transportation carrier and rotated vertical, the backbone of the launch vehicle was lifted up into High Bay 3 of the Vehicle Assembly Building (VAB) at the Kennedy Space Center (KSC) and bolted to its two Solid Rocket Boosters (SRB).

Now that the Core Stage and boosters are bolted together, EGS and Jacobs can now branch work out into parallel paths, beginning to plug SLS into the EGS control system to prepare for months of testing and checkouts while continuing to stack the rest of the launch vehicle and eventually the Orion spacecraft.

The first flight SLS Core Stage and boosters were “soft-mated” around 9 pm Eastern on June 12 and “hard-mated” at approximately 6 am on June 13, after six weeks at KSC of post-Green Run refurbishment, lift preparations, and then crane operations in the VAB to move the Core into place with the boosters on the Mobile Launcher.

When connected, the Core’s primary forward attach points rest on top of the boosters’ forward attach interfaces.  The forward Core Stage attach fittings are at the ends of the main thrust beam running through the intertank.

Once fully mated, the weight of the Core Stage is supported by the boosters.

At liftoff, the boosters will pick up the Core Stage through the intertank thrust beam and hoist the whole flight vehicle into the sky.

After the boosters burn out, separation bolts will disconnect them from the Core Stage — with booster separation motors firing to push them safely away.

Mating of the “partial stack” of the Core and boosters is a major milestone in the first Orion/SLS launch campaign.  The SLS Core Stage was the final Artemis 1 flight hardware element to arrive for launch in late-April, completing its double-duty as the program’s propulsion test article for the special Green Run design verification campaign

The hard-mating of the Core Stage and boosters also allows a branching out of multiple work paths over the next several weeks

(Photo Caption: NASA diagrams of the forward and aft connections between the SLS Core Stage and Boosters

The left diagram is a side cross-section of the attachment that shows that the Core Stage (CS) rests on top of the Boosters (SRB). The right diagram is looking down the length of the vehicle from the top towards the bottom to show the three struts that connect each booster to the engine section on opposite sides of the Core.)

In parallel with preparation for the Integrated Modal Test later in the processing flow, the rest of the SLS is now preparing to be stacked on top of the Core Stage

The upper SLS elements can now line up for their turn, beginning with the Launch Vehicle Stage Adapter (LVSA)

The lower flange on the LVSA will be bolted to the forward skirt of the Core Stage and then that mated flange will be closed out with spray-on foam insulation

The MSO doesn’t represent the form and fit of Orion, but it does mimic the mass and center of gravity of the spacecraft in its launch configuration and can stand in for the spacecraft for the Integrated Modal Test, which is planned as a one-time only exercise

Immediately after the Core Stage and boosters were hard-mated, the forward skirt area became a busy location with preparations for stacking the LVSA as well as getting the Core Stage Forward Skirt Umbilical connected

The first task was to open up access to the forward skirt volume by using the still-attached crane to remove the lift spider and weather cover, the latter of which has been attached to the Core Stage since New Year’s 2020

“Once we’re hard-mated to the boosters, they have direct access to that [forward skirt] flange, so they’ll disconnect the weather cover and the lift ring, and the weather cover will fly with the [lift spider on the crane]

“The Core Stage Forward Skirt Umbilical [connection] we have to balance that out around the LVSA foaming operation to make sure we get that portion of the flange done [and] also balance that out with the RINU optics.”

(Photo Caption: As seen from high on the umbilical tower of Mobile Launcher-1, the Core Stage is suspended in position in High Bay 3 to be connected to the two SLS Boosters on June 12. Over the next few weeks, the rest of the SLS flight hardware will be stacked on top, along with an Orion mass simulator for upcoming testing and checkout of the launch vehicle and ground control systems.)

Another connection from the Mobile Launcher to the forward skirt is the Vehicle Stabilizer System (VSS), which is a liftoff-released, two-point attachment that helps dampen vehicle motion on the Mobile Launcher due to winds when it is outside, either on the launch pad or while it is being moved between the pad and the VAB

“The Vehicle Stabilizer will need to be mated before the Integrated Modal Test, but we know we need the Core Stage Forward Skirt [Umbilical mated] to be able to power up the vehicle

We know we need to get that Launch Vehicle Stage Adapter and Core Stage forward flange closed out and foamed

For the first round of tests through the Integrated Modal Test, the structural test article (STA) of the Orion Stage Adapter will be stacked with the rest of the SLS vehicle and the Orion mass simulator rather than the flight article