Ending an era in US rocketry, the United Launch Alliance launched its 16th and final triple-core Delta 4 Heavy on Tuesday, a classified spy satellite in the family's last hurray before the dawn of the space age.
Heavy's three hydrogen-fueled RS-68A first stage engines ignited with a bright orange flame at 12:53 pm EDT, smoothly pushing the 235-foot rocket from Pad 37 at the Cape Canaveral Space Force Station in Florida.
United Publishing Alliance
The launch was delayed by 12 days due to work to replace a pump in the system that supplies nitrogen gas to several launch sites from a pipeline that runs through Kennedy Space Center and the Cape Canaveral Space Force Station. Tuesday was no problem.
Mounted atop the rocket is a classified satellite provided by the National Intelligence Office, the secretive government agency that manages the nation's sophisticated optical and radar imaging spy satellites and electronic listening stations.
As per standard NRO-US Space Force policy for such missions, there are no details on that NROL-70 payload were released. But six hours after launch, the National Reconnaissance Office declared the launch a success, indicating that the satellite had reached its planned orbit.
Before the rocket's initial launch attempt, NRO Director Chris Scolis told reporters, „All of our missions are very important, and this one ranks up there. „But this one is even more special because it will be the last flight of the Delta 4 Heavy.
„As with all of our work, we believe they focus on national security and provide the best information in the world for our policymakers, warfighters and civil society.”
Based on the heavy's easterly trajectory, safety announcements and other factors, independent investigators concluded the payload was an advanced signals intelligence satellite in geosynchronous orbit 22,300 miles above the equator.
Satellites at that altitude appear fixed in the sky while orbiting in lockstep with Earth's rotation, allowing for continuous observation of specific areas.
Such signals intelligence satellites are believed to have giant mesh antennas that span space, acting as „big … 'ears' in the sky, monitoring large areas for radio emissions, especially military (communications),” says Marco Langbroek. Independent researcher based in the Netherlands.
When asked specifically about the nature of the NROL-70 satellite, Scolese told reporters, „There's not much to say other than that it's a national security payload that's going to provide a very sophisticated capability that a lot of people and companies need. Clearly policymakers, the military and others don't know what's going on.” can know.”
However, as is standard procedure for classified missions, ULA ended its launch coverage by confirming secondary engine ignition and payload fairing separation seven minutes after liftoff. The rest of the ascent was carried out in secret.
The final appearance of the Delta rocket 63 years after the first variant's first flight was an emotional milestone for the managers, engineers and technicians who assembled and launched the last member of the family.
„It's bittersweet for me to finally launch Delta 4,” Col. Eric Zaribnisky, director of the NRO's Office of Space Launch, said in a statement. „I was part of the team that launched the first Delta 4 for NRO. Since that time, Delta 4 has put an amazing amount of capability into orbit for this nation.”
Tori Bruno, president and CEO of United Launch Alliance, called the flight a „bittersweet” moment as the company continues its transition to the next-generation Vulcan rockets, phasing out its expensive Delta and Atlas families.
„Soon, Vulcan will take up that mantle, and we're going to retire this venerable rocket that has done so much important work for our country,” he said after the launch in a pre-recorded video.
„I want to thank everyone involved with Delta 4 Heavy. We have many crew members who were here for the first Delta 4 launch and are still here for the last Delta 4 launch to send this great vehicle into its well. — a well-earned retirement.”
He told reporters earlier that closing the Delta runway „is obviously the future, moving to Vulcan as a low-cost, high-performance rocket. But it's still sad.”
The single-core Delta 4 and triple-core Heavy are expensive, with some versions of the Heavy said to have sold for more than $300 million each. Although capable of placing high-priority military payloads into complex, hard-to-reach orbits, the program is not considered sustainable in an era of small, large numbers of satellites and low-cost boosters from SpaceX.
The Delta family of stages and rockets has its roots in the early space program, first serving in the nation's fleet of intermediate-range ballistic missiles and evolving through several versions used to put military, NASA, and civilian payloads into orbit.
The now-retired Delta 2 launched in 1990, putting the first Global Positioning System satellites into orbit and sending several planetary probes into deep space, including Messenger to Mercury, several Mars orbiters, Pathfinder, the Spirit and Opportunity Mars rovers, Spitzer and more.
The single-core Delta 4 flew in 2002 with the first heavy two years later. The single-core version made its final flight of the project in 2019. Tuesday's launch was the 45th flight of the Delta 4 and the 16th and final Delta 4 Heavy.
„We're very excited to be flying these missions with Vulcan, but at the same time we love this rocket,” Bruno said of the Delta family.
„Delta has been around in one form or another for 60 years,” he added. „It has a storied legacy, and it's done great things for our nation. We're very proud to have been a part of it, and although Vulcan is the future, I'm personally sad to see it go.”