CAPE CANAVERAL SPACE FORCE STATION — United Launch Alliance has postponed its final launch of the Delta IV Heavy rocket due to an issue with the launch vehicle systems.

The 235-foot rocket was supposed to take off from Space Launch Complex-37 at Cape Canaveral Space Force Station at 2:45 p.m. ET on Thursday, but after a hold in the countdown, ULA announced it had to scrub the launch due to "an issue with the gaseous nitrogen pipeline which provides pneumatic pressure to the launch vehicle systems. The team initiated operations to secure the vehicle," ULA posted on X, formerly known as Twitter.

On Thursday night in an email to the media, ULA stated that its team was troubleshooting the pipeline and that more time is needed.

“We will continue to work with our customer to confirm our next launch attempt and a new launch date will be provided upon resolution,” ULA stated.

That means the new launch time that was given after Thursday’s scrub —1:37 p.m. ET, Friday — is no more.

Weather was also a big concern and threaten the last lift off of the Delta IV Heavy. On Wednesday, the 45th Weather Squadron stated the launch had a 30% chance of favorable liftoff conditions, with the concerns being ground winds and the cumulus cloud rule.

Spectrum News meteorologist Reid Lybarger offered more details of what the forecast might look like come launch time.

“A passing cold front will bring scattered showers and the chance for an isolated thunderstorm near Cape Canaveral around lunchtime on Thursday. Storms won't be particularly strong, but winds will be breezy with gusts up to 20 to 25 mph and higher within storms,” he stated.

Because of the weather, it pushed back the launch from 1:40 p.m. ET, then to 2:03 p.m. ET and finally at 2:45 p.m. ET.

When it does go up, it will send up the top-secret NROL-70 mission for the National Reconnaissance Office (NRO).

Unlike SpaceX rockets, ULA’s Delta IV Heavy rocket does not land.

About the Delta Heavy rocket

This will be the Delta IV Heavy’s 16th and final launch. In its near 20-year history, it has performed mostly classified missions for the U.S. government and all 15 missions were considered successful.

“United Launch Alliance is preparing to launch the final Delta IV Heavy rocket this week for the National Reconnaissance Office. Dating back to 1960, the Delta program enabled the original GPS satellite constellation and numerous scientific pursuits, including (eight) Mars missions for NASA,” the company stated.

In fact, the Delta IV heavy rockets have been instrumental for both the U.S. Space Systems Command (SSC) and NRO.

And as stated, they have been used for scientific missions, such as the Orion spacecraft and the Parker Solar Probe.

The Delta IV Heavy rocket was easily recognized in the Space Coast’s skies for its white-and-orange color scheme and its three first-stage rocket boosters, also called common booster core tanks.  

The production of the Delta IV Heavy hailed from different parts of the country and different companies contributed to its making, stated ULA.

1. Canoga Park, CA
RS-68A Engine Fabrication at
Aerojet Rocketdyne, an L3Harris Technologies Company

2. Denver, CO
ULA Headquarters &
Design Center Engineering

3. Decatur, AL
Booster, Payload Fairing and
Second Stage Fabrication

4. West Palm Beach, FL
RL10C-2-1 Engine Fabrication at
Aerojet Rocketdyne, an L3Harris Technologies Company

The last time the Delta IV Heavy graced Florida’s skies was in June 2023 for the NROL-68 mission.

In fact, the NROL-70 mission is the last one for any member of the Delta rocket family. The Delta II rocket had a 29-year career of sending up various missions until it was retired in 2018, ULA stated.

What will replace the Delta IV Heavy, and the company’s Atlas V which is still going strong, is the Vulcan Centaur, which had its first successful maiden launch in January of this year.

About the NROL-70 mission

Not much is known about the classified NROL-70 (National Reconnaissance Office Launch) mission for the NRO. Neither ULA nor NRO revealed what the classified payload is.

Although, SSC did state this in a press release: “Assured Access to Space (AATS) is the program executive office within Space Systems Command that is responsible for delivering next-generation launch and on-orbit capabilities in support of the warfighter, combatant commands, intelligence agencies, civil services, allied nations, and the commercial space industry.”

Senior materiel leader for SSC’s Launch Execution Delta Col. Jim Horne praised the working relationship with ULA.

“We’ve worked alongside ULA and in close coordination with our NRO partners to prepare this Delta IV Heavy, our last Delta ever, and in just a few days the team’s hard work will culminate in this highly anticipated and historic launch,” said Horne in the press release. “These launches place critical capabilities into orbit for our nation and our allies in what are dynamic times for the space community. Every member of our launch team understands what’s at stake and works with care and efficiency to prepare for what’s going to be a tremendous launch.”

Watch the launch