United Launch Alliance scheduled its Vulcan Centaur rocket to lift off Friday from Cape Canaveral Space Force Station with 40 Amazon Leo broadband satellites, the booster's first flight in nine months^1,2.

Liftoff from Space Launch Complex 41 was set for 12:54 p.m. EST (1754 UTC), the opening of a 29-minute window, Spaceflight Now reported, on a northeasterly track². Space.com said coverage was to begin 20 minutes before launch¹.

Vulcan last flew Feb. 12 on a U.S. Space Force mission, when a solid-rocket booster nozzle burned through, according to both outlets^1,2. A similar nozzle failure occurred on an October 2024 flight; both missions still reached orbit^1,2.

The Space Force paused national security flights on Vulcan until the problem is addressed^1,2. ULA said in an Oct. 28 update that it had identified potential contributors and would fly an improved nozzle while testing continues¹.

Spaceflight Now reported the February investigation remained open and that ULA, Northrop Grumman and government agencies had identified three credible causes without publicly naming them². ULA President and CEO Mark Peller said the Space Force wants to review data from this commercial flight before deciding on national security use².

The mission, Amazon Leo LV-01, is the first of 38 Vulcan launches Amazon purchased and Vulcan's first for the constellation formerly called Project Kuiper^1,2. After two Centaur burns, satellite separations were to start about 70 minutes after liftoff over about 25 minutes^1,2.

Spaceflight Now said the rocket would fly in a six-booster VC6L configuration with a shorter Centaur 5 stage for low Earth orbit and more than 50,000 pounds of payload, a ULA record². Space Force weather forecasters gave a 90 percent chance of acceptable weather².

The flight is also the first of Blue Origin BE-4 engines on Vulcan since a New Glenn exploded on the pad in a May static-fire test; Blue Origin installed a retrofit kit on the oxidizer valve, Peller said². Space.com did not report that engine change¹.

Amazon has launched about 400 Leo satellites on Atlas V, Falcon 9 and Ariane 6, Space.com said; Spaceflight Now put the count at nearly 400 across 14 missions since April 2025, none since July^1,2. Melissa Wuerl, Amazon Leo's director of launch systems, said Vulcan would launch close to half of the first-generation constellation².