United Launch Alliance is preparing for its Seminole moment for its Atlas 5 rocket, which is preparing to launch its 58th and final national security mission on Tuesday. The United States Space Force 51 (USSF-51) mission will mark ULA’s 100th national security mission launch.
Following the completion of launch readiness reviews on Friday, ULA moved the rocket to the launch pad at Space Launch Complex 41 (SLC-41) at the Cape Canaveral Space Command Station. The first move took place just after noon Saturday, with the journey wrapping up just after 12:30 pm EDT.
The launch is scheduled for Tuesday, July 30th, during a three-hour window beginning at 6:45 a.m. EDT (10:45 a.m. UTC).
“This is a bittersweet moment for us. I had the honor of sitting at the console for the first National Security Atlas launch in 2007, STP-1 (Space Test Program 1) in March of that year, and now the last National Security Atlas is launching,” said Col. Jim Horn, senior materiel leader for Launch Execution Delta. “I want to thank the entire team, the government and ULA. We’ve had a strong partnership in this program for the past nearly two decades, and this Atlas has been our workhorse.”
Due to the nature of the launch, Horn declined to discuss specifics of the mission or whether there was one or multiple payloads during the flight.
“There’s not much I can say about why this is a mission of critical national security importance in this era of increasing great power competition, but that’s all I can say at this point,” Horn said.
An Atlas 5 launching the USSF-51 payload will fly in the 551 configuration, meaning five solid rocket boosters supported by a short payload fairing 17 feet (5 meters) in diameter. The full stack will be about 196 feet (59.7 meters) tall.
Gary Wentz, ULA’s vice president of government and commercial programs, said after this mission, nine of the remaining 15 Atlas 5 rockets will fly in the 551 configuration to support Amazon’s Project Kuiper Constellation.
“You learn a lot every time you fly, and we’re flying five GEM 63s on this mission,” Wentz said. “We’ll learn from it and continue to get data and apply it to future Atlas missions.”
Passing the baton
This final mission, conducted as part of the Atlas 5 rocket’s National Security Space Launch (NSSL), marks a significant turning point for ULA: following the launch of USSF-51, ULA will now turn its attention fully to the second certification flight of the Vulcan rocket following its successful debut in January.
“What we’ll do after this mission is complete is check out the ground systems. [mobile launch platform]”Once we’ve performed a checkout of the Atlas MLP and verified that everything is in order, we’ll bring in the Vulcan launch platform for a checkout and then we’ll immediately begin deploying the booster and preparing for the Cert-2 mission,” Wentz said.
“We’re not going to waste any time. We expect to have the hardware ready for Cert. flight within a week and a half to two weeks.”
As the ground team in Cape Town prepared the Atlas 5 rocket for deployment, the ULA team in Decatur watched as the vessel dubbed “Rocket Ship” set sail carrying the third Vulcan booster, which will be used for USSF-87, the first NSSL mission to be launched on a Vulcan rocket.
The Alliance’s Horizontal Integration Facility at Cape Canaveral Space Force Station will support the rocket’s second certification flight prior to launch of a national security payload. Image: Will Robinson Smith/Spaceflight Now
Dr. Walt Lauderdale, mission director for the USSF-51 mission, said the U.S. Space Command and ULA worked closely together during Vulcan’s development, and that the dozens of missions flown on Atlas have helped him and his team navigate the certification process.
“Given our partnership with ULA, it’s important that they have a deep knowledge and understanding of the vehicle systems, the ground systems and how they work together,” Lauderdale said. “You can do all the modeling in the world, but there’s no substitute for real live data, real data from the vehicles and systems.”
“Cert-1 was a great flight and it allowed us to validate a lot of the things we’ve been working on with them at that point. Cert-2, as Col. Horn said, gives us an opportunity to take all of the knowledge we’ve gained from the model, all of the qualifications, all of the testing we’ve done and make sure there are no surprises,” Lauderdale added. “What we’re really looking for in Cert-2 is to make sure there are no surprises and that it’s well-bounded by our experience and our qualification knowledge.”
“And this sets the stage for us to move forward with confidence to launch Vulcan. Everything is going well right now, and it’s not over until it’s done.”
