Overnight from Cape Canaveral, United Launch Alliance sent an Atlas V rocket streaking into the dark Florida sky. The fleet carrying it into history is now down to just a handful of flights. An era is about to end.
The launch itself went smoothly. The Atlas V 551 lifted off from Space Launch Complex-41 within the short window opening at 12:24 a.m. ET. on July 2nd. 
 It was the eighth Atlas V liftoff for the Amazon Leo megaconstellation, and the vehicle flew in its most powerful configuration, the 551, with five solid rocket boosters, a 5-meter payload fairing, and a single-engine Centaur upper stage.
But the bigger story is what's ending. Atlas V has been flying since 2002, and in 2021 ULA announced it would stop selling new Atlas V missions. Before retiring, it still had to work through its existing contracts. But this backlog has been steadily shrinking ever since. By late last year, only two customers remained on the manifest: Boeing's Starliner crew capsule and Amazon's satellite constellation. And we know that the slots reserved for Starliner might very likely become available for different customers sooner or later.
So, why does ULA retire what looks like a very capable rocket with a good track record? Well, the answer is geopolitical as much as technical. Atlas V's first stage relies on the Russian-built RD-180 engine, and ULA made its final purchase of those engines back in 2021, cutting off future supply. Its replacement, Vulcan Centaur, was built specifically to end that dependency, pairing Blue Origin-built BE-4 engines with an Aerojet Rocketdyne Centaur V upper stage in an entirely domestic design.
What's next for the Atlas V you ask? A handful more flights are left. It is not yet clear, when the last flight will take place. Some say it might be as late as 2030, but this late date is connected to Starliner. If it turns out that capsule will not return, or at least not enter regular service, the end for Atlas V might come a lot sooner.
Either way, once those final contracts are fulfilled, Vulcan will become ULA's sole launcher, closing the book on an iconic rocket's colorful history.