Leo will compete with SpaceX's Starlink, which had a four-year start over Amazon and has more than 10,000 satellites in its constellation.

A United Launch Alliance Atlas 5 551 rocket stands at Space Launch Complex 41 at Cape Canaveral Space Force Station ahead of the Leo Atlas 8 (LA-08) mission launch. Image: John…

Launch is scheduled for 12:24 a.m. ET on Thursday (July 2).