ULA Flies the Final Atlas V 551, Lofting 29 Amazon Leo Satellites and Leaving Just Six Atlas Vs Reserved for Starliner
United Launch Alliance flew the last Atlas V 551 on July 2, ending the rocket's satellite-launching career; its six remaining vehicles are held for Boeing's Starliner as Amazon Leo pivots to Vulcan.
Overview
United Launch Alliance flew the final Atlas V rocket in its 551 configuration in the early hours of July 2, 2026, lofting 29 Amazon Leo broadband satellites from Space Launch Complex 41 at Cape Canaveral Space Force Station, according to Spaceflight Now. It was also the last Atlas V that will ever carry a satellite payload, according to SpaceNews: the six Atlas V rockets ULA has left are all reserved for Boeing’s CST-100 Starliner spacecraft, Spaceflight Now reported.
A Workhorse Bows Out
The rocket, designated AV-114, was the 110th Atlas V to fly, and it lifted off at 12:30 a.m. EDT (0430 UTC), according to Spaceflight Now. The “551” designation reflects the vehicle’s build-out — a five-meter payload fairing, five solid rocket boosters, and a single-engine Centaur upper stage, per Spaceflight Now.
With the launch complete, ULA has just six Atlas V vehicles remaining, all of them held for Starliner missions flying in the N22 configuration with dual-engine Centaur upper stages, according to Spaceflight Now. SpaceNews reported that the timing of those flights is uncertain because of continuing technical problems with Starliner.
Across the Amazon Leo campaign, Atlas V launched 224 of the constellation’s satellites at a 100 percent success rate, Amazon Leo director of launch systems Melissa Wuerl said, according to SpaceNews. Amazon had purchased nine Atlas V missions from ULA back in 2021 for the network, SpaceNews reported. Thursday’s flight brought the total number of Amazon Leo satellites in orbit to 396, according to Spaceflight Now.
Amazon’s Race Against the FCC Clock
The retirement of Atlas V as an Amazon Leo launcher comes as the company confronts a regulatory deadline it is set to miss. Amazon holds a Federal Communications Commission license for 3,232 satellites and has said it eventually plans to deploy more than 7,700, according to The Register. The FCC required the company to have 50 percent of its planned constellation in orbit by July 30, 2026 — a target it will miss with only 396 satellites deployed, The Register reported.
Amazon sought an extension of that deadline in January 2026, and the request was granted in June, though with conditions attached, according to The Register. As previously reported, Amazon had been pressing for that relief as the low-Earth-orbit broadband race intensified. The company has said it expects to begin offering service over the network later this year, according to The Register.
The Vulcan Handoff
Future Amazon Leo satellites will fly on ULA’s newer Vulcan Centaur rocket. Amazon has purchased 38 Vulcan launches but has not yet flown any, in part because of Vulcan’s development delays, according to SpaceNews. The first Vulcan flight carrying Amazon Leo satellites is expected sometime in the third quarter of 2026, according to Spaceflight Now.
What We Don’t Know
When the six remaining Atlas V rockets will fly is unclear; SpaceNews noted their schedule hinges on resolving Starliner’s technical problems. Neither the specific conditions attached to Amazon’s FCC deadline extension nor a firm start date for commercial service has been detailed, according to The Register.