Yesterday, NASA Stennis successfully completed a hot fire test of Aerojet Rocketdyne RS-25 a.k.a SSME. It was noted in the webcast before the test started that they were testing the 'engine controller'. I also read about testing the new 3d printed 'pogo' for the engine.
- What are these components and what function do they serve? Why have a test dedicated to these?
Looking at the live test video one could gather they tested for about 7 mins in which the back pressure area of blue radiation or the first shock was noticably varying, which would imply variable thrusting.
So, while doing that how did they exactly test the two components? What data were they looking for?
How does passing this test pave way for further tests that are planned, ultimately to the EM-1 mission?