Vulcan Centaur Cert-2 Flight Had "an Anomaly"

I have to confess to not getting up to watch the scheduled 6:00 AM Vulcan launch this morning. It has been a few days with things going on that have been a bit more tiring than usual and sleeping in sounded better.  Not so much storm cleanup but what could be prep for the inevitable next one.  Sleeping in made it impossible to know that the launch was aborted in the last minute, and after various precautions they recycled to launch at 7:25 AM (1125 UTC) this morning.

A friend of mine sent a quickie email saying, "looked OK from the front yard" but he's a bit farther from the Cape than I am and I don't think what happened would have been visible without a powerful, guided telescope from here. What happened? Essentially a RUD (Rapid Unscheduled Disassembly) of one of the two solid rocket boosters strapped onto the core stage of the Vulcan. The (composite, not metal) exhaust nozzle of one those boosters broke apart in flight. The booster didn't blow up, the Vulcan Centaur continued on its mission with one of the boosters putting out significantly less thrust than the other. 

As the rocket arced east from Cape Canaveral, a shower of sparks suddenly appeared at the base of the Vulcan rocket around 37 seconds into the mission. The exhaust plume from one of the strap-on boosters, made by Northrop Grumman, changed significantly, and the rocket slightly tilted on its axis before the guidance system and main engines made a steering correction.

Videos from the launch show the booster's nozzle, the bell-shaped exhaust exit cone at the bottom of the booster, fall away from the rocket.

"It looks dramatic, like all things on a rocket," Bruno wrote on X. "But it’s just the release of the nozzle. No explosions occurred."

As is often the case in situations like this, a good guy to check out is Scott Manley, and he posted a good video on this early today.  This is a screen grab of Scott's screen grab from another source (D Wise at NASA Spaceflight).  The broken off section of the nozzle is in the red circle. It was tumbling and the moment I grabbed the picture was when you can look through the nozzle - still glowing hot - and see the sky behind it.

Remarkably, the solid rocket didn't explode, the Vulcan's control systems saw that the thrust was lower than expected and the rocket wasn't on the planned trajectory, so it adjusted what it could to regain a nominal flight.  The main stage with it's Blue Origin-supplied BE-4 methane/oxygen engines burned seconds longer than the normal, expected flight, and then shut down and fell away, as it should have. The Centaur V upper stage started and burned, with the onscreen video's timer showing the Centaur's RL-10 engines burned approximately 20 seconds longer than planned, apparently also to compensate for the lower thrust from the damaged booster during the first phase of the flight. The Centaur upper stage completed a second burn about a half-hour into the mission.

ULA CEO Tory Bruno considered the mission a success, saying "Orbital insertion was perfect" on X. The US Space Force hailed the test flight as a "certification milestone" in a press release after the launch. Clearly, both ULA and Space Force have a vested interest in certifying the Vulcan for the National Security missions it will carry; equally clearly, US Space Force would face more criticism for approving the Vulcan if this should recur. Or get worse.  

A photo taken a few seconds after liftoff shows the BE-4 Main engines with their light blue Mach Diamonds, accompanied on both sides by the solid rocket boosters. Both appear to be "normal and healthy" in this photo. Image credit: United Launch Alliance