STENNIS SPACE CENTER, Miss. — For a few moments, it seemed like the Space Launch System saga might have a happy ending. Beneath brilliant blue skies late on Saturday afternoon, NASA’s huge rocket roared to life for the very first time. As its four engines lit and thrummed, thunder rumbled across these Mississippi lowlands. A giant, beautiful plume of white exhaust billowed away from the test stand.
It was all pretty damn glorious until it stopped suddenly.
About 50 seconds into what was supposed to be an 8-minute test firing, the flight control center called out, “We did get an MCF on Engine 4.” This means there was a “major component failure” with the fourth engine on the vehicle. After a total of about 67 seconds, the hot fire test ended.
During a post-flight news conference, held outside near the test stand, officials offered few details about what had gone wrong. “We don’t know what we don’t know,” said NASA Administrator Jim Bridenstine. “It’s not everything we hoped it would be.”
He and NASA’s program manager for the SLS rocket, John Honeycutt, sought to put a positive spin on the day. They explained that this is why spaceflight hardware is tested. They expressed confidence that this was still the rocket that would launch the Orion spacecraft around the Moon.
And yet it is difficult to say what happened Saturday is anything but a bitter disappointment. This rocket core stage was moved to Stennis from its factory in nearby Louisiana more than one calendar year ago, with months of preparations for this critical test firing.
Honeycutt said before the test, and then again afterward, that NASA had been hoping to get 250 seconds’ worth of data, if not fire the rocket for the entire duration of its nominal ascent to space. Instead it got a quarter of that.
So what happened?
Perhaps most intriguing, Honeycutt said the engine problem cropped up about 60 seconds into the test, at one of its most dynamic moments. This was when the engines were throttling down from 109 percent of nominal thrust to 95 percent, Honeycutt said. And it is also when they began to gimbal, or move their axis of thrust.
At approximately 60 seconds, engineers noted a “flash” in the area of a thermal protection blanket around Engine 4, Honeycutt said. The engine section is one of the most complex parts of the core stage, and each of the four main engines has thermal protection to limit heating from the other engines.
Now, engineers from NASA, Boeing and the engine manufacturer, Aerojet Rocketdyne, will study data from the test to determine what exactly went wrong. It is not clear how long this will take, or what problems will need to be fixed. Via – Ars Technica