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<\/p>\nThe launch campaign for NASA\u2019s 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. Launch preparations are progressing towards the first power-up of the Artemis 1 Space Launch System (SLS) rocket, which will allow the Exploration Ground Systems (EGS) launch team to begin digital diagnostics.<\/p>\n
The Integrated Test and Checkout (ITCO) of the flight and ground systems will include special engineering tests for the Orion and SLS Programs. Up to this point, mathematical models were used to analyze and predict how the different systems would work when assembled on the launch platform; over the next few months, some of the tests will help calibrate those analytical models while others verify that the vehicle is ready to launch for the first time.<\/p>\n<\/p>\n
First-flight engineering tests included in pre-launch checkouts<\/p>\n
There is more to launch preparations than stacking the pieces and bolting them together. The Artemis 1 flight vehicle is a group of interconnected machines that each controls different phases of the launch and mission.<\/p>\n
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). After TLI, Orion separates from the ICPS on its way to the Moon and the Orion spacecraft\u2019s flight control system then performs the Artemis 1 mission, navigating in and out of lunar orbit and back to Earth.<\/p>\n
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).<\/p>\n
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.<\/p>\n
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Credit: NASA.<\/p>\n
(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.)<\/em><\/p>\n \u201c[Testing is] a good truth model for us,\u201d Dr. John Blevins, NASA\u2019s Chief Engineer for the SLS Program, said in a July 12 interview. \u201cAs 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. We put [a] load on the booster, and we really measured the stiffness, if you will, the compliance of the joint on the bottom of the booster where it is on the vehicle posts. So ITCO has already started.\u201d<\/p>\n 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.<\/p>\n \u201cWe did do a ping test when it was on the crane, and then we also did three shakers at Stennis Space Center to get those modes if you will, the displacements through the structure as we excite the structure,\u201d Blevins said. \u201cWe 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.\u201d<\/p>\n \u201cThe Integrated Modal Test is one of the more exciting ones,\u201d Blevins observed. \u201cWe\u2019re going to do that with the integrated vehicle; that modal test has got six shakers to do that. We\u2019ve already done some modal testing down at KSC. We took the crawler transporter system and did a modal test on that. We did it with and without the Mobile Launcher. And now we\u2019ll have the vehicle on the Mobile Launcher, so we\u2019ve got this modal test with the six shakers to do that in place.\u201d<\/p>\n 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. The shakers that vibrate the structure are not just vibrating the vehicle structures, but also the ground support equipment they are attached to.<\/p>\n Additional testing and data was performed and gathered on the ground equipment at Stennis and KSC by themselves.<\/p>\n