United Launch AllianceLaunch SuccessfulCommunications

Amazon Leo

Name: Atlas V 551 | Amazon Leo (KA-01)
Start: 2025-04-28T23:01:00Z
Location: Space Launch Complex 41, Cape Canaveral SFS, FL, USA

Atlas V 551 · KA-01

Launched Mon, Apr 28 · 11:01 PM UTC2025-04-28 23:01 UTCSpace Launch Complex 41, Cape Canaveral SFS, FL, USA

Reached orbit

Follow United Launch Alliance in the app Watch the replay

Success

Reached Low Earth Orbit

The second stage shut down at T+18:15.

Worldwide

90th

orbital launch attempt in 2025

United Launch Alliance

1st

launch this year

Space Launch Complex 41

1st

launch from this pad this year

Pad turnaround

206 d 11 h

since the pad's previous launch

Replay

Replay: 🔴 LIVE 🔴 Rocket Launch: Atlas V Kuiper 1

The Flight Plan

Planned times, from liftoff at 11:01 PM UTC. The result is at the top of the page.

Countdown1

T−0:0311:00 PMStart of the engine ignition sequence

Show the countdown (1 step)

T−0:0311:00 PMStart of the engine ignition sequence

Ascent8

T+0:0111:01 PMFirst upwards movement of the rocket
T+0:0411:01 PMVehicle is supersonic
T+0:3511:01 PMMaximum dynamic pressure
T+0:4611:01 PMSeparation of the side boosters
T+3:0511:04 PMSeparation of the payload fairing
T+4:2311:05 PMBooster Engine Cutoff
T+4:2911:05 PMSeparation of the second stage from the first
T+4:3911:05 PMFirst start of the second engine

Second Stage and Payload1

T+18:1511:19 PMFirst cut-off of the second engine

Mission

Amazon Leo, formerly known as Project Kuiper, is a mega constellation of satellites in Low Earth Orbit that will offer broadband internet access, this constellation will be managed by Kuiper Systems LLC, a subsidiary of Amazon. This constellation is planned to be composed of 3,276 satellites. The satellites are projected to be placed in 98 orbital planes in three orbital layers, one at 590 km, 610 km and 630 km altitude.

27 satellites are carried on this launch.

Launch Provider

United Launch Alliance

Commercial · United States of America · Founded 2006 · CEO Mark Peller

United Launch Alliance (ULA) is a joint venture of Lockheed Martin Space Systems and Boeing Defense, Space & Security. ULA was formed in December 2006 by combining the teams at these companies which provide spacecraft launch services to the government of the United States. ULA launches from both coasts of the US. They launch their Atlas V vehicle from LC-41 in Cape Canaveral and LC-3E at Vandeberg. Their Delta IV launches from LC-37 at Cape Canaveral and LC-6 at Vandenberg.

Launches

175

Successful

175

100%

Upcoming

scheduled

FliesAtlas Delta Vulcan

All United Launch Alliance launches Website Wikipedia

Updates

Apr 29 · 12:43 AM
Launch success.
Cosmic_Penguin
Apr 28 · 11:01 PM
Liftoff.
Cosmic_Penguin
Apr 28 · 10:48 PM
New T-0.
Cosmic_Penguin
Apr 27 · 2:27 PM
Updated launch weather.
Cosmic_Penguin
Apr 18 · 10:48 PM
Rescheduled for April 28.
Cosmic_Penguin

Show earlier updates

Apr 12 · 1:25 AM
NET April 28.
Cosmic_Penguin
Apr 12 · 12:21 AM
Reverted back to April TBD.
Cosmic_Penguin
Apr 10 · 6:31 AM
NET April 14 per marine navigation warnings, TBC.
Cosmic_Penguin
Apr 10 · 12:47 AM
Scrubbed for the day, next attempt TBD.
Cosmic_Penguin
Apr 10 · 12:21 AM
New T-0.
Cosmic_Penguin
Apr 10 · 12:00 AM
New T-0.
Cosmic_Penguin
Apr 9 · 11:44 PM
New T-0.
Cosmic_Penguin
Apr 9 · 11:22 PM
New T-0.
Cosmic_Penguin
Apr 9 · 11:00 PM
New T-0.
Cosmic_Penguin
Apr 9 · 10:54 PM
Updating launch weather.
Cosmic_Penguin
Apr 9 · 10:47 PM
Holding at T-4 minutes.
Cosmic_Penguin
Apr 9 · 10:31 PM
Official Webcast by United Launch Alliance has started
Launch Library 2
Apr 8 · 5:23 PM
Weather is 55% GO.
hitura-nobad
Apr 7 · 2:58 PM
New launch window.
Cosmic_Penguin
Apr 2 · 5:15 PM
GO for launch.
Cosmic_Penguin
Apr 2 · 4:07 PM
NET April 9.
Cosmic_Penguin
Oct 3 · 4:16 AM
NET Q1 2025.
Cosmic_Penguin
Jun 27 · 6:53 PM
NET Q4 2024.
Cosmic_Penguin

Atlas V 551

Vehicle history

Height

59.7m

Diameter

3.8m

To low Earth orbit

18,850kg

Liftoff thrust

12,269kN

Space Launch Now for iOS and Android

Notifications before every launch you follow, live countdowns on your home screen and watch, and webcasts as they start.

See what's in the app

Scan to open on your phone

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United Launch AllianceLaunch SuccessfulCommunications

Amazon Leo

Atlas V 551 · KA-01

Launched Mon, Apr 28 · 11:01 PM UTC2025-04-28 23:01 UTCSpace Launch Complex 41, Cape Canaveral SFS, FL, USA

Reached orbit

Follow United Launch Alliance in the app Watch the replay

Success

Reached Low Earth Orbit

The second stage shut down at T+18:15.

Worldwide

90th

orbital launch attempt in 2025

United Launch Alliance

1st

launch this year

Space Launch Complex 41

1st

launch from this pad this year

Pad turnaround

206 d 11 h

since the pad's previous launch

Replay

Replay: 🔴 LIVE 🔴 Rocket Launch: Atlas V Kuiper 1

The Flight Plan

Planned times, from liftoff at 11:01 PM UTC. The result is at the top of the page.

Countdown1

T−0:0311:00 PMStart of the engine ignition sequence

Show the countdown (1 step)

T−0:0311:00 PMStart of the engine ignition sequence

Ascent8

T+0:0111:01 PMFirst upwards movement of the rocket
T+0:0411:01 PMVehicle is supersonic
T+0:3511:01 PMMaximum dynamic pressure
T+0:4611:01 PMSeparation of the side boosters
T+3:0511:04 PMSeparation of the payload fairing
T+4:2311:05 PMBooster Engine Cutoff
T+4:2911:05 PMSeparation of the second stage from the first
T+4:3911:05 PMFirst start of the second engine

Second Stage and Payload1

T+18:1511:19 PMFirst cut-off of the second engine

Mission

27 satellites are carried on this launch.

Launch Provider

United Launch Alliance

Commercial · United States of America · Founded 2006 · CEO Mark Peller

Launches

175

Successful

175

100%

Upcoming

scheduled

FliesAtlas Delta Vulcan

All United Launch Alliance launches Website Wikipedia

Updates

Apr 29 · 12:43 AM
Launch success.
Cosmic_Penguin
Apr 28 · 11:01 PM
Liftoff.
Cosmic_Penguin
Apr 28 · 10:48 PM
New T-0.
Cosmic_Penguin
Apr 27 · 2:27 PM
Updated launch weather.
Cosmic_Penguin
Apr 18 · 10:48 PM
Rescheduled for April 28.
Cosmic_Penguin

Show earlier updates

Apr 12 · 1:25 AM
NET April 28.
Cosmic_Penguin
Apr 12 · 12:21 AM
Reverted back to April TBD.
Cosmic_Penguin
Apr 10 · 6:31 AM
NET April 14 per marine navigation warnings, TBC.
Cosmic_Penguin
Apr 10 · 12:47 AM
Scrubbed for the day, next attempt TBD.
Cosmic_Penguin
Apr 10 · 12:21 AM
New T-0.
Cosmic_Penguin
Apr 10 · 12:00 AM
New T-0.
Cosmic_Penguin
Apr 9 · 11:44 PM
New T-0.
Cosmic_Penguin
Apr 9 · 11:22 PM
New T-0.
Cosmic_Penguin
Apr 9 · 11:00 PM
New T-0.
Cosmic_Penguin
Apr 9 · 10:54 PM
Updating launch weather.
Cosmic_Penguin
Apr 9 · 10:47 PM
Holding at T-4 minutes.
Cosmic_Penguin
Apr 9 · 10:31 PM
Official Webcast by United Launch Alliance has started
Launch Library 2
Apr 8 · 5:23 PM
Weather is 55% GO.
hitura-nobad
Apr 7 · 2:58 PM
New launch window.
Cosmic_Penguin
Apr 2 · 5:15 PM
GO for launch.
Cosmic_Penguin
Apr 2 · 4:07 PM
NET April 9.
Cosmic_Penguin
Oct 3 · 4:16 AM
NET Q1 2025.
Cosmic_Penguin
Jun 27 · 6:53 PM
NET Q4 2024.
Cosmic_Penguin

Atlas V 551

Vehicle history

Height

59.7m

Diameter

3.8m

To low Earth orbit

18,850kg

Liftoff thrust

12,269kN

Next From Cape Canaveral SFS

Cape Canaveral SFS schedule

Nov—NET

Cygnus CRS-2 NG-25SpaceX · Falcon 9 Block 5 · Space Launch Complex 40, Cape Canaveral SFS, FL, USALow Earth OrbitTo be determinedNET November Nov—NET

Amazon Leo (LV-01)United Launch Alliance · Vulcan VC6L · Space Launch Complex 41, Cape Canaveral SFS, FL, USALow Earth OrbitTo be determinedNET November

Space Launch Now for iOS and Android

Notifications before every launch you follow, live countdowns on your home screen and watch, and webcasts as they start.

See what's in the app

Scan to open on your phone

Amazon Leo

Replay

More Videos

The Flight Plan

Countdown1

Ascent8

Second Stage and Payload1

Mission

United Launch Alliance

Updates

Atlas V 551

Amazon Leo

Replay

More Videos

The Flight Plan

Countdown1

Ascent8

Second Stage and Payload1

Mission

United Launch Alliance

Updates

Atlas V 551

Next From Cape Canaveral SFS

Next From Cape Canaveral SFS

Amazon Leo

Replay

More Videos

The Flight Plan

Countdown1

Ascent8

Second Stage and Payload1

Mission

United Launch Alliance

Updates

Atlas V 551

Never Miss a Launch.

Amazon Leo

Replay

More Videos

The Flight Plan

Countdown1

Ascent8

Second Stage and Payload1

Mission

United Launch Alliance

Updates

Atlas V 551

Next From Cape Canaveral SFS

Never Miss a Launch.

Next From Cape Canaveral SFS