Timelapse of the launch of Amazon Leo AL-04 early this morning. Photo: Charles Boyer / Talk of Titusville.
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.”
Atlas V lifts off from SLC-41 at Cape Canaveral Space Force Station on December 16, 2025 Photo: Charles Boyer
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
Next Launch
Next Launch: Falcon 9 Block 5 | Starlink Group 6-99
Go for LaunchKennedy Space Center • LC-39A
Mission
Starlink Group 6-99 (29 satellites)
Organization
SpaceX
Rocket
Falcon 9
Launch Site
Kennedy Space Center, Florida, USA
Pad
Launch Complex 39A (LC-39A)
Window Opens
Wednesday, 12/17/2025 • 7:19:00 AM (ET)
Window Closes
Wednesday, 12/17/2025 • 11:19:00 AM (ET)
Destination
Low Earth Orbit
Status Info
Current T-0 confirmed by official or reliable sources.
Mission Description
A batch of 29 satellites for the Starlink mega-constellation — SpaceX’s
project for a space-based Internet communication system.
Countdown (to window open)
—
As of:— (your local time)
Launch times are subject to change due to weather, range operations, and mission requirements.
Liftoff of Atlas V on the Amazon Leo 4 Photo: United Launch Alliance
ULA Atlas V ViaSat-3 liftoff. Credit: United Launch Alliance
On an Atlas V 551 rocket, United Launch Alliance successfully launched the ViaSat-3 Flight 2 (F2) mission for Viasat, Inc. Liftoff was at 10:04 p.m. ET from SLC-41 at Cape Canaveral Space Force Station. The mission was a success.
This launch concluded a rare day at The Cape: two different rockets from two different manufacturers launching on the same day, with none of them being a Falcon 9. SpaceX is well known for launching twice in one day from the Eastern Range, but this time was a bit different: Blue Origin was launching New Glenn for only the second time, and later, ULA was launching Atlas V on its last mission past low-earth orbit. There are only 11 launches left for Atlas V: six Starliner flights (if they happen) and five Project Kuiper (now Amazon LEO) missions.
In a post-flight press release, Gary Wentz, ULA vice president of Government and Commercial Program said, “At ULA, we pride ourselves in delivering our customer’s spacecraft precisely to orbit and serving as the catalyst for our customers to enable global connectivity. We partner in the shared goals of connecting the world and this successful launch aligns with this core mission. Thank you Viasat for your trust in our shared visions and successful partnership.”
For this mission, the Atlas V 551 configuration placed the ViaSat-3 F2 ultra-high-capacity broadband satellite into a geosynchronous transfer orbit (GTO). Once operational, the spacecraft is expected to substantially boost both the capacity and adaptability of Viasat’s global, multi-orbit network, which serves consumer, commercial and government users. Engineered to add 1 Tbps of throughput to that network, ViaSat-3 F2 will help meet rising demand for secure, dependable, high-bandwidth connectivity services across the Americas.
Atlas V and USSF-51 sitting on its launch pad on July 29, 2024 Photo: Charles Boyer / Talk of Titusville
United Launch Alliance is planning to launch an Atlas V tomorrow morning from Space Launch Complex 41 at Cape Canaveral Space Force Station. The launch window opens at 06:45 AM EDT and extends to 11:45 AM the same day.
The payload for this mission is classified and is for the United States Space Force’s Space Systems Command (SSC). No other information is publicly available.
In their press materials, ULA notes that “The Atlas V USSF-51 mission on Tuesday is the 100th ULA launch dedicated to national security.” They also note that this is the last national security mission for Atlas V, and that future missions will be aboard the company’s new rocket, Vulcan.
Atlas V sitting on its launch pad on July 29, 2024 Photo: Charles Boyer / Talk of Titusville
At A Glance
Mission: USSF-51
Date: NET July 30, 2024
Launch Window: 06:45 AM – 11:45 AM EDT*
Weather: 80% Go during the primary launch window
Organization: United Launch Alliance
Rocket: Atlas V 551
Trajectory: Easterward
Launch Site: SLC-41, Cape Canaveral Space Force Station
The 45th Weather Squadron has released their weather forecast, and it’s a good one as far as launches go: only a 20% probability of violation, meaning the forecasters expect an 80% chance of acceptable weather during the launch window.
The 45th’s main concerns are, “The possibility of showers and an isolated thunderstorm near or just off the Spaceport coast in the mornings Tuesday and Wednesday. The Cumulus Cloud Rule and Anvil Cloud Rules are the concerns for the primary launch window and Cumulus Cloud Rule is the concern for the backup launch window.”
via 45th Weather Squadron Retrieved July 29, 2024
Trajectory
The rocket’s trajectory will be East-Southeast as it rises, effectively straight away from the coast if you are facing the Atlantic Ocean in Florida.
Online Viewing
United Launch Alliance will have a live feed of the launch beginning at 06:25 AM EDT
Spaceflight Now will have coverage of the launch starting about one hour before liftoff on Youtube: link
For official updates regarding launch times, ULALaunch.com is the best source of information.
Remember that there is a delay between a launch stream and the actual countdown clock. That is simply because of physics: it takes time for the signal to travel from the launch site, through the Internet, and back down to your phone, resulting in a five to fifteen-second delay.
Next Space Launch an app for iOS and Android phones, has a real-time countdown clock that is accurate to a second, give or take. The app is free. Search the App Store or Google Play.
Launch Viewing: In Person
This morning’s planned launch is from SLC-41, on the south side of the Eastern Range (KSC and Cape Canaveral Space Force Station combined.) The southern parks in Titusville on Washington Avenue and FL-528/A1A in Cape Canaveral are the best spots to watch liftoff directly.
Given the early hours of the launch window (0:645AM – 11:45AM EDT) these restaurants may not be open for launch viewing. Later in the day, all three may well be, so if you are interested, be sure to call ahead to make sure they’ll be ready to serve you.
The Space Bar ($$$) – atop the Courtyard Marriott near Kennedy Parkway
New York New York ($$) – on the Indian River with an outdoor seating area. Is family-friendly.
Shiloh’s ($$$) — located on the Indian River with an outdoor deck overlooking KSC/CCSFS
Indirect Views
There are several excellent viewing spots for SLC-41 launches that offer indirect views — meaning you won’t see the rocket until it clears obstructions such as trees, buildings, even a storm berm in one case.
Parking fees (probably). Pay with your smartphone on the parking app. There are signs everywhere telling you how.
Further away, but still good views.
Northern Titusville Parks
Further away, but really nice views.
Playalinda Beach
Playalinda Beach out on the Cape Canaveral National Seashore will be open to spectators at 6:00 AM EDT, that is if KSC Security and the National Park Service allow viewers for the launch. That’s a bit tight for a 06:45 AM launch, but this may be an option available to you. I cannot stress this enough: Call ahead to be sure.
Cape Canaveral National Seashore • Playalinda Beach Phone: (386) 428-3384 x0 Current operating hours: 6:00 AM–8:00 PM
If you are going to Playalinda, and if it is open, remember these general tips. Some may not apply to this particular launch.
Get there at least two hours early, or better, earlier than that. Lines are long at the entry gate and they will only allow as many spectator vehicles as there are parking space available.
If the launch L-0 time is moved to after 8PM, you must leave Playalinda, as the National Park Service is very strict about closing hours.
Cape Canaveral National Seashore has a fee to get in and cash is not accepted. Debit and credit cards are okay, or if you have one of the National Park Service’s passes for the Seashore or the National Parks, that will work as well.
Cellphone service is spotty at best and often non-existent at Playalinda. Don’t count on your cellphone to keep up with the launch; you might get a signal, or you might not.
You are not allowed to view from the pullouts on Beach Road. Stanchions will block them. You’ll have to park and go to the beach.
Refreshments are not available. There are no stores at Cape Canaveral National Seashore, so you’ll need to bring drinks and food if you want any while you’re there.
Rangers will keep you back a certain distance from the launch area on the beach. Even if the beach is open, you’ll still be unable to go down to the fence that demarcates the normal security zone. There’s a line that spectators can’t go past somewhat north of the fence. That’s for safety and security.
Be prepared for potential changes or pushbacks in the launch schedule, and keep up by monitoring the live stream links mentioned above.
Keep up with launch news and other space events that affect the local area by subscribing to alerts when we publish a new article by entering your email at the link at the bottom of this page, or by visiting Space Talk here on the website. It’s free, and you
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