After years of development, the moment is finally here: Amazon will send two of its Kuiper test satellites to space, as the company looks to take on reigning incumbent SpaceX with its own satellite internet constellation.

The two prototypes will launch aboard a United Launch Alliance Atlas V rocket from Cape Canaveral in Florida during a two-hour launch window that opens at 2 PM EST. In a recent blog post, Amazon said the two satellites – dubbed KuiperSat-1 and KuiperSat-2 – are “the first iterations of more than 3,200 satellites Project Kuiper plans to manufacture and deploy over the next six years.”

Although the company will have a long way to go before filling the skies with its mega-constellation, the launch represents a key milestone and will no doubt give Amazon’s technical Kuiper team tons of data on satellite performance.

“We’ve done extensive testing here in our lab and have a high degree of confidence in our satellite design, but there’s no substitute for on-orbit testing,” said Rajeev Badyal, Project Kuiper’s vice president of technology. “This is Amazon’s first time putting satellites into space, and we’re going to learn an incredible amount regardless of how the mission unfolds.”

Like SpaceX’s Starlink, customers will be able to use Kuiper internet by purchasing individual terminals. This prototype mission will test how the satellites interact with those terminals, as well as the ground systems that the satellites will use to communicate with Earth.

Amazon is aiming to launch its first production satellites in the first half of next year and start beta testing with customers by the end of 2024. The company has a bit of pressure to move fast: it has to have at least half of its planned constellation in orbit by 2026 to be in compliance with its spectrum license from the U.S. Federal Communications Commission.

Back in 2020, Amazon said it would invest more than $10 billion in Kuiper across the ground network, satellite testing and manufacturing, and user terminals.