Nozzle blows off of Northrop Grumman SLS solid rocket booster during static fire test
During a static fire test of a new upgraded strap-on solid-fueled booster to be used on the second version of NASA’s SLS rocket, it appears the nozzle broke off near the end of the test.
I have embedded the video below.
This failure is not good for getting the upgraded version of SLS built, dubbed Block 2. Block 1 has flown once unmanned, and is planned for the next two manned missions. Block 2 would be for further manned missions beyond that. The Trump administration has proposed cancelling it, ending SLS after those two Block 1 flights. Senator Ted Cruz (R-Texas) has instead introduced a bill that would save it in order to fly two Block 2 SLS manned missions.
This failure is definitely going to delay and add cost to Block 2 development, a program that is already over budget many times over and a decade-plus behind schedule. These additional delays and cost overruns are not going to help it politically. It justifies the Trump administration’s desire to cancel it.
Moreover, this nozzle failure suggests a very fundamental design problem. Northrop Grumman, which built and was testing this booster, also builds the solid-fueled strap-on boosters used on ULA’s Vulcan rocket, which had a similar nozzle failure during Vulcan’s second launch in October last year. Both Northrop Grumman and ULA have said they had identified and fixed the cause of that failure, and the military has certified it for operational launches, but nonetheless Vulcan still remains sidelined, more than eight months later.
I suspect ULA is going to have to do more testing of the Northrop Grumman Vulcan side boosters before its next Vulcan launch, delaying that rocket further.
Nozzle blew off near the end of the test. https://t.co/nJZ4yXL1hd pic.twitter.com/wvjxrv7HPP
— NSF – NASASpaceflight.com (@NASASpaceflight) June 26, 2025
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
During a static fire test of a new upgraded strap-on solid-fueled booster to be used on the second version of NASA’s SLS rocket, it appears the nozzle broke off near the end of the test.
I have embedded the video below.
This failure is not good for getting the upgraded version of SLS built, dubbed Block 2. Block 1 has flown once unmanned, and is planned for the next two manned missions. Block 2 would be for further manned missions beyond that. The Trump administration has proposed cancelling it, ending SLS after those two Block 1 flights. Senator Ted Cruz (R-Texas) has instead introduced a bill that would save it in order to fly two Block 2 SLS manned missions.
This failure is definitely going to delay and add cost to Block 2 development, a program that is already over budget many times over and a decade-plus behind schedule. These additional delays and cost overruns are not going to help it politically. It justifies the Trump administration’s desire to cancel it.
Moreover, this nozzle failure suggests a very fundamental design problem. Northrop Grumman, which built and was testing this booster, also builds the solid-fueled strap-on boosters used on ULA’s Vulcan rocket, which had a similar nozzle failure during Vulcan’s second launch in October last year. Both Northrop Grumman and ULA have said they had identified and fixed the cause of that failure, and the military has certified it for operational launches, but nonetheless Vulcan still remains sidelined, more than eight months later.
I suspect ULA is going to have to do more testing of the Northrop Grumman Vulcan side boosters before its next Vulcan launch, delaying that rocket further.
Nozzle blew off near the end of the test. https://t.co/nJZ4yXL1hd pic.twitter.com/wvjxrv7HPP
— NSF – NASASpaceflight.com (@NASASpaceflight) June 26, 2025
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Hi Bob,
Nice summary, and of course, reasonable conclusions about what this means for the Artemis Program if Congress insists on it employing the Space Launch System. BOLE is a modest evolution of very old tech, after all — a solid rocket architecture that goes back to 1972 in development, and operation in 1981. It’s reasonable for NASA to ask why Northrop’s SRM division is still blowing the ends off of these boosters in 2025. Starship (whatever mistakes have been made in its development) at least is a clean sheet launch system which is vastly more ambitious at every level. Is it, indeed, related to the nozzle explosion we saw on Vulcan’s first flight? We could be forgiving for wondering if that is the case.
One minor correction, if I may:
The iterations of the SLS are a little more complicated than that. There is the current Block 1, and then there is the Block 2, but in between is the Block 1B. Block IB’s major change is the replacement of the ICPS upper stage with the more powerful Exploration Upper Stage, currently under expensive and much delayed development by Boeing (it also entails the switch to the equally expensive and delayed Mobile Launcher 2 currently being built by Bechtel). The Block 2’s major change, in turn, is the upgrade to the BOLE solid rocket boosters, which (so the theory goes) are justified because Northrop will have exhausted its supply of the casings for the current 5 segment SRB’s.
The schedule for each of these iterations goes like this:
Block 1: Artemis I, II, III
Block IB: Artemis IV, V, VI, VII, VIII
Block 2: Artemis IX — onward
https://www.nasa.gov/reference/sls-space-launch-system-solid-rocket-booster/
The White House has proposed just flying Artemis II and III, and then cancelling the SLS. That would mean no Block IB or Block 2!
Chairman Ted Cruz (of the Senate Commerce, Science, and Transportation Committee) is proposing going beyond that, to preserve Artemis IV and V as currently configured. That requires the Block 1B, because ULA can’t build any more ICPS stages. So that means finishing the EUS, and the ML-2, and the Gateway, because these are all required for the Block 1B missions. All that for….just two flights.
Meanwhile, Northrop is still developing the BOLE SRB’s for the Block 2 missions, because (alas) they have not been cancelled yet.
Richard M: The added details about this SLS program are appreciated. I simplified things in order to get the post up.
Great…
Official statement of Northrop Grumman to NSF: ““Today’s test pushed the boundaries of large solid rocket motor design to meet rigorous performance requirements. While the motor appeared to perform well through a harsh burn environment, we observed an anomaly near the end of the two-plus minute burn” — Jim Kalberer, vice president, propulsion systems, Northrop Grumman.
Not an explanation, but I suppose it was too much to hope for more today.
I can’t remember the last time that happened on solids of that size.
Starship coming apart, nozzles coming apart…I was to train some kid today….no-show.
What in the Sam Hill is going on?
Jeff Wright,
Maybe the kid got hit by a piece of flying booster nozzle? :)
I hate composites.
I hoped Dynetics Pyrios would have replaced SRBs.
Pyrios was like the very early (non-BO) Jarvis low-cost booster concept that also was to have a stainless steel upper stage.
Pyrios should have been Vulcan…this way it would have a market outside of whether SLS lived or died.
The upper stage was to use a simple J-2 derivative, instead of another RL-10 under Centaur tankage that one of my sneezes could have torn through.
Energiya had RS-25/SSME class RD-0120s with channel wall. Each of its Zenit first stage strap-ons had an F-1 equivalent RD-170 that had four nozzles.
Pyrios was to have two F-1s apiece.
Hu Davis (Buzz’s StarBooster engineer) wanted something similar as an SRB–except winged.
The poor man is dead now.
I enjoyed talking to him, the late David Christensen, and Truax fan John London of LEO ON THE CHEAP, a book on pressure-feds.
But everyone wants to copy SpaceX.
Marshall had SLI, a re-usable program…also axed.
I liked X-34…which has been treated very badly.
There have been so many different projects that never had a patron…an Elon of their own.
So help me–but I seem to remember a story of how Gates was to bring back the Saturns (freshened up) as part of his Starlink like Teledesic–before he married the equivalent of Paul Allen’s sister.
I thought for sure the Woz would have funded space more than he has.
One of my favorite books is THE DREAM MACHINES–but I haven’t read it in ages…the last time I paged through it I just wept.
Dunsany is a favorite author of mine–he had his own cosmology in ” The Gods of Pegana.”
C.S. Lewis invented much more beautiful names–like “Perelandra.”
One of the many hearth deities Dunsany had was Jabim…the god of lost and broken things.
I can imagine him paging through it in HPL’ s Dreamlands…especially at the land of dreams unattained.
Jeff Wright,
Anent predecessor events to the recent BOLE SRB nozzle failure, there was a very similar incident during a test of a prototype of what is now the standard SRB for SLS. Happened back in 2019 as I recall.
A girl sci-fi fan I knew back in the day was also a Dunsany admirer. Perhaps I should look into his stuff.
The X-34 certainly was treated badly. NASA has a pretty dismal track record in that respect. The indifference of OldSpace contractors who have no love for anything that no longer makes them any money doesn’t help.
“The 20th Century Renaissance Man Who Pioneered Much of the Modern Fantasy Genre….”
Edward John Moreton Drax Plunkett, 18th Baron Dunsany
https://youtu.be/AJKfoLUN47M
34:17