The United Launch Alliance (ULA) Atlas V 551 rocket successfully launched 27 satellites for Amazon's Project Kuiper at 23 UTC on April 28, from Space Launch Complex-41(SLC-41) at Cape Canaveral Space Force Station, Florida. Kuiper 1 (KA-01) mission is the first to send fully operational Kuiper satellites into low Earth orbit (LEO).
The satellites were deployed into a near-circular LEO at approximately 450 kilometers(km) altitude with a 51.9-degree inclination. This mission carried the heaviest payload ever flown by an Atlas V, requiring a longer-than-standard payload fairing, used only for the ninth time in 102 Atlas V launches.
The Atlas V 551 rocket followed a northeasterly trajectory, with the Centaur upper stage deorbited into the Pacific Ocean after satellite deployment to minimize space debris.
"While the satellites complete the orbit-raising process, we will look ahead to our ultimate mission objective: providing end-to-end network connectivity," Amazon representatives wrote in a prelaunch statement.
"This involves sending data from the internet, through our ground infrastructure, up to the satellites, and down to customer terminal antennas, and then repeating the journey in the other direction," they added.
The initial Project Kuiper constellation aims to consist of more than 3,236 LEO satellites to provide fast, reliable internet to customers worldwide, particularly in unserved and underserved communities.
Project Kuiper is expected to begin providing coverage to customers later this year, according to Amazon.
Project Kuiper, managed by Kuiper Systems LLC (an Amazon subsidiary), aims to compete with SpaceX’s Starlink and Eutelsat’s OneWeb by delivering low-latency broadband. The constellation will operate across 98 orbital planes at altitudes of 590 km, 610 km, and 630 km. Amazon plans to begin customer service once 578 satellites are operational, per FCC requirements.
Monday's launch cost approximately $153 million, reflecting the Atlas V 551’s high-performance configuration.
The launch follows a successful protoflight mission in October 2023, which launched two prototype Kuiper satellites to validate the system’s technology. It was the first of more than 80 planned launches to build out the Project Kuiper megaconstellation.
Beyond ULA, Amazon has secured 18 launches on Arianespace’s Ariane 6, 12 on Blue Origin’s New Glenn (with options for 15 more), and three on SpaceX’s Falcon 9, diversifying its launch providers to meet the aggressive deployment schedule.
Amazon has some work to do if it wants to catch up with its main competitor: SpaceX has launched 31 Starlink missions so far this year, with many more on the docket. In fact, there was a Starlink launch less than three hours before today's Atlas V launch, with another planned for less than four hours after.
SpaceX's Starlink broadband network, which already beams service down to customers around the world, currently consists of more than 7,300 operational spacecraft.
Kuiper 1 was ULA’s first Atlas V launch of 2025 and the first of eight Atlas V missions contracted by Amazon for Project Kuiper, with 38 additional launches booked on ULA’s Vulcan rocket.
An earlier Kuiper 1 launch attempt on April 9, 2025, was scrubbed due to offshore thunderstorms and cumulus clouds violating weather safety rules, particularly the risk of rocket-triggered lightning. The launch was rescheduled after coordination with the U.S. Space Force’s Eastern Range, which manages Cape Canaveral’s launch schedule.
Kuiper 1 mission marked the 250th flight of a Centaur upper stage atop an Atlas rocket and the 275th overall for Centaur.
The Atlas V 551 configuration includes five solid rocket boosters and a medium-length payload fairing, making it the most robust setup for this mission. It is also the most powerful variant of the Atlas V family, featuring a 5.4-meter payload fairing, five Northrop Grumman GEM-63 solid rocket boosters (SRBs), and a single-engine Centaur upper stage powered by an Aerojet Rocketdyne RL10 engine. The rocket stands 62.5 meters tall, weighs approximately 589,000 kilograms when fueled, and generates 12 megaNewtons of thrust at liftoff.
"This Atlas V, designated AV-107, is a two-stage rocket that incorporates five GEM 63 solid rocket boosters, features a single RL10A-4-2 engine on the Centaur upper stage and encapsulates the spacecraft in a 5.4-meter-diameter (17.7-foot) payload fairing," ULA wrote on X before launch Monday.
