United Launch Alliance is preparing to launch an Atlas 5 rocket on Tuesday, its 58th and final national security mission. The United States Space Force-51 (USSF-51) mission will also be the 100th national security mission launch for ULA.
After completing a launch readiness check on Friday, ULA rolled the rocket to the launch pad at Space Launch Complex 41 (SLC-41) at Cape Canaveral Space Force Station. The first move occurred shortly after noon Saturday, and the journey ended just after 12:30 p.m. EDT.
Liftoff is scheduled for Tuesday, July 30, during a three-hour window opening at 6:45 a.m. EDT (1045 UTC).
“This is a bittersweet moment for us. I had the privilege of sitting at the console for the first launch of a National Security Atlas in 2007, STP-1 (Space Test Program 1) in March of that year and here we are with our final National Security Atlas,” said Col. Jim Horne, senior materiel leader for Launch Execution Delta. “I want to thank the entire team, the government and ULA. It’s been a strong partnership over these past nearly 20 years on this program and this has been our workhorse vehicle.”
Because of the nature of the launch, Horne declined to go into details about the mission or whether the flight carried a single payload or more than one.
“I can't say too much about that because this is a very important mission for national security in these times of great competition between powers, but that's really all we can say at this point,” Horne said.
The Atlas 5, which will launch the USSF-51 payload, will fly in a 551 configuration, meaning it will be supported by five solid rocket boosters and a short, 17-foot (5-meter) diameter payload fairing. The full stack is about 196 feet (59.7 meters) tall.
Gary Wentz, ULA's vice president of Government and Commercial Programs, said that after this mission, of the 15 remaining Atlas 5 rockets, nine will fly in the 551 configuration in support of Amazon's Project Kuiper constellation.
“Every time you fly, you learn a lot. On this mission, we’ll be flying five GEM 63s,” Wentz said. “We’ll learn from it, continue to get data, and in the future, apply it to future Atlas missions.”
Passing the baton
This latest mission, as part of the National Security Space Launch (NSSL) on the Atlas 5 rocket, marks a turning point for ULA. Following the launch of USSF-51, ULA will now turn its full attention to the second certification flight of its Vulcan rocket, following a successful debut in January.
“What we'll do after this mission flies is check out the ground system with the (mobile launch platform), the Atlas MLP, verify that everything is OK, then we'll bring the Vulcan launch platform up, do a checkout and immediately begin assembling the rocket and preparing for the Cert-2 mission,” Wentz said.
“We will not waste any time. In a week and a half or two we will have the hardware ready for the certification flight.”
As ground crews in Cabo prepared to launch the Atlas 5 rocket, ULA teams in Decatur watched as the barge named RocketShip set sail with the third Vulcan rocket on board. It will be used for the first NSSL mission to launch a Vulcan rocket: USSF-87.
Alliance Horizontal Integration Facility at Cape Canaveral Space Station. It will support the rocket's second certification flight ahead of launching national security payloads. Image: Will Robinson-Smith/Spaceflight Now
Dr. Walt Lauderdale, USSF-51 mission director, highlighted the close working relationship between the U.S. Space Force and ULA during the development of Vulcan. He said the dozens of missions flown on Atlas are also helping inform him and his teams as they work through the certification process.
“When we think about working with ULA, that partnership, it really means having that deep knowledge and understanding of the vehicle systems, the ground systems, how they interact,” Lauderdale said. “You can do all the models in the world, but there’s nothing that can replace real, live data, real vehicle and system data.”
“Cert-1 was a fantastic flight. It allowed us to validate a lot of things that we’ve worked on with them up to that point, and as Colonel Horne just said, Cert-2 gives us the opportunity to take everything we know about the models, all the qualifications, all the testing we’ve done and make sure there are no surprises,” Lauderdale added. “That’s really what we’re looking for with Cert-2 – to make sure there are no surprises and that it’s well-rounded by our experience and our knowledge of the qualifications.
“And that really sets the stage for us to confidently move forward with Vulcan launches. Everything seems to be going well right now and we're not done until we're done.”
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