Amazon’s second batch of satellites reached orbit early Monday aboard one of the final flights of United Launch Alliance’s Atlas V rocket.

It is the company’s second launch in support of Amazon’s $10 billion Kuiper Project, a network of low Earth orbit satellites that will deliver low-latency broadband to global customers. Monday’s launch placed 27 Kuiper Project satellites into orbit, doubling the total to 54, out of an initial planned 3,232.

The launch was postponed a week due to anomalies detected in the booster engine of the Atlas V while preparing to lift off June 16.

“We are proud to continue our strong partnership with Amazon and empower their mission to bridge the digital divide through reliable satellite technology,” said Gary Wentz, ULA vice president of government and commercial programs, in a news release.

The rocket lifted off just before 6 a.m. from Cape Canaveral Space Force Station in Florida. An hour later, ULA posted on X that all Kuiper satellites had been successfully deployed.

Five side-mounted GEM 63 solid rocket boosters, a Russian-made RD-180 booster system and a single RL10A-4-2 upper-stage engine powered ULA’s Atlas V rocket. Northrop-Grumman made the boosters, while the upper stage is a product of L3Harris’ Aerojet Rocketdyne. ULA is a joint venture between Boeing Co. and Lockheed Martin Corp.

Monday’s launch had the same configuration ULA used to launch the first Kuiper mission in April, which placed Amazon’s initial batch of 27 satellites into LEO. For most future Kuiper Project flights, though, ULA is planning an upgrade.

Amazon has contracted with ULA to launch 46 Kuiper flights, which will deploy the majority of the former’s satellite constellation. Of those, 38 will use ULA’s new super-heavy Vulcan platform, which will allow larger batches of satellites to be put into orbit.

Blue Origin makes the BE-4 rocket engines for Vulcan in Huntsville, which are then integrated with the rocket at ULA’s Decatur factory. For Monday’s launch, the booster, upper-stage Centaur tank and payload fairing were made and assembled in Decatur.

ULA is phasing out the Atlas V in part to cut reliance on the Russian RD-180.

Amazon is facing a Federal Communications Commission deadline to launch 1,618 satellites, or just over half of its constellation, by July 2026. SpaceX’s Starlink, in comparison, currently has more than 7,700 satellites in orbit and 6 million worldwide users.

ULA’s next launch is the first Vulcan mission for the U.S. Space Force, the classified USSF-106, scheduled for this summer.