One down, ten to go: United Launch Alliance launched an Atlas V 551 this morning from SLC-41 at Cape Canaveral in partly cloudy cool winter skies. Launch was at the top of the window, 3:28 AM ET.

Aboard the venerable rocket were 27 Amazon Leo satellites, which will now join the other 152 satellites in low Earth orbit (LEO) as Amazon begins building its orbital-based Internet service offering. The company plans for over 3,200 in its full constellation, aiming for initial service by early 2026.

“One of our primary missions at ULA is to be a catalyst in connecting the world,” said Gary Wentz, ULA vice president of Atlas and Vulcan programs. “Partnering with Amazon contributes to their mission of bridging the global digital gap. We thank the Amazon Leo team for their continued collaboration.”

 Trajectory was northeastward, at roughly 44-45º, aiming for a final orbit inclination of around 51.9º at roughly 630 km (391 miles.)

Tonight’s launch leaves only ten Atlas V’s remaining: six for Starliner, four more for Amazon Leo. The rocket has been in service for over 23 years, since its inaugural launch on August 21, 2002. Originally designed and developed by Lockheed Martin for the U.S. Air Force’s EELV program, with manufacturing/operations later consolidated under ULA. It has launched over 100 missions to date, but will be replaced by the new ULA-designed Vulcan rocket.

Launch Replay

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Author: Charles Boyer

NASA kid from Cocoa Beach, FL, born of Project Apollo parents and family. I’m a writer and photographer sharing the story of spaceflight from the Eastern Range here in Florida.