In a recent blog post, NASA Stennis announced the arrival of a new component for testing. The interstage test article will be used when it comes time for the Exploration Upper Stage (EUS) to undergo its own green run test, just like the Space Launch System’s Core Stage did last year
At first glance, this test article looks like something else. It would be easy to mistake this as a pathfinder of the EUS itself, given the similar dimensions. A pathfinder is a hollow shell of the rocket component it mimics. Pathfinders are used for checking that the finished product fits to the other components as designed. But this isn’t a pathfinder for the EUS.
This interstage test article will be used in conjunction with the first EUS as it undergoes its green run test. According to the blog post, this interstage will serve two purposes. First, just like the actual interstage, it will protect the four RL-10 engines from the environment, similar to what the real interstage will do while the vehicle is on the pad and in flight. Second stages generally don’t have as much protection around their engines since they are only exposed to space and used while in a vacuum. Interstages protect them until then. Secondly, the top of the interstage simulator will take the thrust from the engines and transfer it back in to the test stand.
There’s still some work to do on it. Built at the Michoud Assembly Facility in New Orleans, the simulator will undergo some sandblasting and protective painting before being mounted into the test stand and connected to various pipes and power connections. NASA Stennis’ video is down below and you can read the full blog post here.