United Launch Alliance (ULA) has flown the final Atlas V mission for Amazon's Leo broadband constellation, closing an important chapter for the once-dominant American launch provider. The launch, from Cape Canaveral last Thursday, sent 29 satellites to orbit and was the 110th flight of the near-flawless Atlas V since its 2002 debut. It matters because ULA's six remaining Atlas V rockets are now effectively locked into launching Boeing's troubled Starliner crew capsule, and there is no easy way to repurpose them for other work even if Boeing does not need them all.

The constraints are largely technical: Starliner flies without a payload fairing, and the Atlas fairing is out of production and not interchangeable with that of ULA's newer Vulcan rocket, while the remaining vehicles carry low-Earth-orbit-optimised dual-engine upper stages and only two strap-on boosters each. NASA last year cut Boeing's guaranteed commercial-crew missions from six to four amid chronic delays, with the next Starliner flight carrying cargo rather than crew. Amazon, which bought all nine unsold Atlas Vs in 2021, is transitioning to Vulcan (38 launches reserved), though Vulcan has been grounded since February over booster problems, and Amazon's other new rockets face setbacks too, leaving Europe's Ariane 6 and SpaceX's Falcon 9 as its only currently available options.