I can't decide whether this was a testament to the robust build of the Vulcan Centaur rocket or whether we just watched a minor miracle happen. 

The ULA Vulcan Centaur is the future of United Launch Alliance's program, and they are depending on it to keep their access to space alive. 

It many ways it is an impressive rocket, and it fills a niche that SpaceX doesn't, at least not yet, and it provides an alternative to SpaceX's Falcon rocket for the Department of Defense and a few other customers. It is intended to replace the Atlas V and Delta IV launchers, which have been reliable performers for years. 

Due to limitations on the Russian rocket engines which have been workhorses, the Centaur uses Blue Origin replacements. 

LAUNCH! ULA's Vulcan launches on its second flight on the CERT-2 mission from SLC-41.

Overview:https://t.co/w0lselfwgK

Live:https://t.co/1gdS8FOXoW pic.twitter.com/9jGMiVM6Sh

— Chris Bergin - NSF (@NASASpaceflight) October 4, 2024

The program has had a slow start and has been very expensive, but its first test flight went off without a hitch. Unfortunately, this time around things didn't go so well. The rocket made it to space, but trouble hit on the way up there. 

Definitely nozzle failure, ULA calling nominal first stage is mildly annoying. Is this is enough to require another cert flight? Also is it a 2-in-a-row requirement or just 2? https://t.co/JoWbD52iru

— random (@r3a9an_k_) October 4, 2024

ULA originally said the launch was nominal, but the video shows otherwise. On first inspection, it looks like one of the solid rocket boosters lost a nozzle, which obviously presents a danger to the spacecraft. 

ULA said that the vehicle’s performance was nominal in the early stages of flight. However, the separation of the two GEM 63XL solid rocket boosters (SRB) took place nearly 30 seconds later than the timeline the company provided before launch. About 35 seconds after liftoff, there appeared to be material coming off one of the boosters, whose plume changed appearance, suggesting damage to the SRB’s nozzle.

ULA did not mention the incident during the ascent, but the timing of subsequent events, including separation of the booster and the shutdown of the Centaur upper stage’s engines after an initial burn, were behind the timeline by up to 20 seconds.

The Centaur completed its second burn about 35 minutes after liftoff, which concluded the main phase of the flight. ULA planned to continue operations of the stage for some time after that to perform experiments with the Centaur.

Remember the Challenger accident? Leaks from SRBs can be deadly. 

ULA has spent ~$7B on Vulcan since 2014, but it can only carry ~20 tons to orbit and is single-use.

SpaceX has spent less than $4B on Starship since 2019, which is designed to lift ~100 tons to orbit and is reusable.

SpaceX just keeps winning! pic.twitter.com/fSlOpRGRGY

— Space Sudoer (@spacesudoer) October 4, 2024

Luckily, this time the rocket survived and made it to orbit with a deadweight payload. This being a certification flight there was no payload. Originally there was going 

The guidance system performed spectacularly. The thrust profile must have been thrown off considerably, but the gimbals on the engines allowed the guidance system to keep the flight on track. That, to me, is impressive. 

ULA nearly loses this rocket, and this is the tweet. Only one company in the entire NASA ecosystem truly prioritizes great product, and its SpaceX. SpaceX announces if their discarded second stage doesnt disintegrate in the right spot in the Pacific ocean…these guys meanwhile https://t.co/kEoB8aGSmH

— therealarod1984 (@therealarod1984) October 4, 2024

It's hard to see how this certification flight leads to certification, though. I am pretty sure the national security customers who are waiting for certification would be leery of using the rocket without further testing. 

ULA certainly doesn't want to wait. It has over $7 billion invested in the rocket and no doubt wants some revenue flights ASAP.