SLS engineering tests to accompany pre-launch checkouts for Artemis 1 - NASASpaceFlight.com - NASASpaceflight.com

July 21, 2021.

July 19, 2021.

July 4, 2021.

The launch campaign for NASA’s Artemis 1 test flight will be punctuated by critical and unique tests to support both pre-launch checkouts of this first-flight vehicle and long-term design objectives.

The Integrated Test and Checkout (ITCO) of the flight and ground systems will include special engineering tests for the Orion and SLS Programs

The Artemis 1 flight vehicle is a group of interconnected machines that each controls different phases of the launch and mission

The Artemis 1 vehicle includes three independent flight control systems

The NASA SLS flight system being flown for the first time will be in control from liftoff to cutoff/suborbital insertion by the Core Stage

At that point, control is handed off to the United Launch Alliance flight system on the Interim Cryogenic Propulsion System (ICPS) for flight through the trans-lunar injection burn (TLI)

All three flight systems need to be aware of each other, and up until shortly before ignition they are responding to directions from the ground launch command and control system

Before the crawler-transporter takes the Mobile Launcher with the vehicle stacked on it out to the launch pad, all those interconnections and their thousands of constituent signals need to be validated during integrated checkouts while parked in the Vehicle Assembly Building (VAB)

In addition to the standard pre-launch checkouts that every Orion/SLS vehicle will go through in the VAB, a number of engineering tests will be carried out during the Artemis 1 campaign as part of the overall development of the spacecraft, launch vehicle, and ground support systems

(Photo Caption: The ICPS in-space stage for Artemis 1 is suspended on one of the VAB cranes in position while being mated to the partially-assembled SLS stack on July 6. Along with preparatory checkouts, the SLS vehicle will be put through a series of engineering tests prior to the Artemis 1 launch.)

John Blevins, NASA’s Chief Engineer for the SLS Program, said in a July 12 interview. “As we stacked and put the boosters together, and before we put the Core Stage on, we did this test that we call the booster pull test

One of the more prominent tests on the Artemis 1 launch processing schedule is the Integrated Modal Test, which is the latest in a series of modal tests that have been performed on different parts of the flight and ground structures

During the Green Run design verification campaign of the Core Stage at the Stennis Space Center, a modal test was performed on the standalone stage while it was suspended on a crane at the test stand

“We basically suspended the vehicle with shakers on it, and we did that modal test and were able to get the information that really went to finalize the finite element model.”

“The Integrated Modal Test is one of the more exciting ones,” Blevins observed

“We’re going to do that with the integrated vehicle; that modal test has got six shakers to do that. We’ve already done some modal testing down at KSC

And now we’ll have the vehicle on the Mobile Launcher, so we’ve got this modal test with the six shakers to do that in place.”

As with the test on the Core Stage by itself at Stennis, the integrated SLS vehicle with a mass and center of gravity Orion simulator on top is still connected to the Mobile Launcher

A dynamic rollout test is planned when the Artemis 1 vehicle rolls out to the launch pad for its last planned series of tests — and then on its way back from the pad to the VAB for final launch closeouts

“Some of them we would call sensor-to-effector testing.” One of those software tests is an “end-to-end polarity test” that demonstrates that gimbaling commands to the SLS Solid Rocket Booster (SRB) nozzles and Core Stage engines from the flight software guidance system are properly translated from vehicle motion sensors

Not all of these are standard; this is a little bit more than a normal rocket because it’s a first launch of a rocket. We won’t do a modal test again [after Artemis 1]; we won’t instrument some of the things as much, but all of those are really important tests,” Blevins added

(Photo Caption: A finite element style rendering of the vehicle configuration that will be used for the Integrated Modal Test (IMT) to be conducted on the SLS and Orion simulator while they are sitting on the Mobile Launcher. A structural test article of the Orion Stage Adapter and a Mass Simulator for Orion will substitute for the flight spacecraft elements during ping and shaker testing.)

The integrated operations team of EGS and prime launch processing contractor Jacobs is working to prepare the SLS part of the Artemis 1 stack for power up by their Spaceport Command and Control System (SCCS) to begin some of the bigger testing and checkouts in the VAB

The connections between all of the SLS flight hardware and the Mobile Launcher will be checked out in the IVT, which is currently projected for mid-August

After the IVT is completed, internal access platforms will be removed from the equipment sections of the Core Stage and other SLS elements will be closed out as if for launch in preparation for the next two tests

The first of those, the Umbilical Release and Retract Test (URRT), will verify the Mobile Launcher’s swing-arm release system, which must safely detach the ground umbilical connections from the vehicle at T0 and quickly swing, or drop as the case may be, the various arms away

That will be followed by the Integrated Modal Test, where the shakers described by Blevins will excite the vehicle as it is attached to the Mobile Launcher through just the eight Vehicle Support Posts on the SRB aft skirts