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
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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
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Every one of those 2020 conclusions has turned out right.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
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You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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…