Roamy here. I previously wrote about the J-2X engine “burp” test. This time, the test is planned for the full duration of 500 seconds. The engine firing is scheduled for today (Nov. 9) at 4 PM Eastern; you can watch it live at
The J-2X blog is here, which is where I got this cool thermal model of the engine during stage separation. I like to think some of my work fed into that.