The Final Flight of Delta IV Heavy scrubbed (again) | Next launch attempt on Tuesday

image credit ULA

After more than six decades of operational service, 388 flights launched since May 1960 and an impressive 95-percent success rate, the conclusion for the Delta Program must wait another day as United Launch Alliance (ULA) has scrubbed its first attempt to get the last Delta IV Heavy rocket airborne. Despite only 30-percent-favorable weather odds, the countdown proceeded past the final built-in hold at T-4 minutes, only to be halted in an ominous “Hold, Hold, Hold” call a couple of seconds later due to an issue with the gaseous nitrogen pipeline, which provides pneumatic pressure to the launch vehicle systems.

ULA then said they would do a 24-hour turnaround, and the launch was planned for 1:37 p.m. Friday.

But In a statement on social media, ULA President and CEO Tory Bruno posted that the “pump failed again … Stand by.”
Just before 8 p.m., ULA said they’d be standing down to continue to work on the pipeline.

“The team continues to troubleshoot the pipeline and more time is needed to instill confidence in the system,” the company said in a statement. “We will continue to work with our customer to confirm our next launch attempt and a new date will be provided upon resolution.”

According to the Federal Aviation Administration there was a launch attempt availability on Monday at 1:25 p.m., but ULA decided to wait another day. Now, the mission is planned to lift off on Tuesday, April 9 from Space Launch Complex-37 at Cape Canaveral Space Force Station in Florida. The launch is planned for 12:53 p.m. EDT. Friday’s forecast shows an 80 percent chance of favorable weather conditions for launch. 

The NROL-70 mission is not just another launch; it's a testament to the technological advancements and strategic capabilities of the NRO. The mission aims to bolster the NRO's capacity to provide critical intelligence information, ensuring national security and aiding global humanitarian efforts.

The Rocket: Delta IV Heavy

The Delta IV Heavy stands as a colossus among rockets, renowned for its immense power and reliability. With this mission, it will have completed 16 successful launches, each contributing to the United States' strategic reconnaissance efforts.
Its design is a marvel of engineering, featuring three common booster cores and a cryogenic second stage, all powered by liquid hydrogen and liquid oxygen. The payload fairing, a metallic trisector, ensures the spacecraft's protection during ascent.

United Launch Alliance’s Delta IV Heavy is a heavy-lift launch vehicle, the largest type of the Delta IV family and one of the world’s most powerful rockets. The Delta IV Heavy configuration is comprised of a common booster core (CBC), a cryogenic upper stage and a 5-meter diameter payload fairing (PLF). The Delta IV Heavy employs two additional CBCs as liquid rocket boosters to augment the first-stage CBC. The Delta IV Heavy can lift 28,370 kg (62,540 lbs) to low Earth orbit and 13,810 kg (30,440 lbs) to geostationary transfer orbit. It is an all liquid-fueled rocket, consisting of an upper stage, one main booster and two strap-on boosters.

The Delta IV was created to fulfill the requirements of the United States Air Force’s Evolved Expendable Launch Vehicle (EELV) program. The inaugural launch of the Delta IV occurred in 2002. NROL-70 is the last ever launch of ULA’s Delta IV of either medium or heavy variants. NROL-70 builds upon a long legacy of NRO Delta IV Heavy launches at Cape Canaveral dating back to 2009.

The PLF (Payload Fairing) encapsulates the spacecraft to protect it from the launch environment on ascent. The 19.8m (63-ft) long PLF makes the vehicle’s height approximately 71.5 m (235 ft).

The DCSS (Delta Cryogenic Second Stage) is a cryogenic liquid hydrogen/liquid oxygen fueled vehicle, with a single RL10C-2-1 engine that produces 110.1 kilo-Newtons (24,750 lbs) of thrust.

The Delta IV booster propulsion is provided by three liquid hydrogen and liquid oxygen-burning RS-68A engines. Each RS-68A engine produces 312.3 kilo-Newtons (705,250 lbs) of thrust for a combined total liftoff thrust of more than 2.1 million pounds.

Launch Details

The NROL-70 will lift off from Space Launch Complex-37 at Cape Canaveral Space Force Station, Florida. The launch window is set for 12:53 p.m. EDT, a time chosen for optimal orbital insertion and mission success.

The Payload

The payload details for the NROL-70 mission are classified, as it is a National Reconnaissance Office (NRO) launch. Typically, NRO missions involve deploying advanced reconnaissance satellites designed to support national security and global humanitarian efforts. The exact nature of the NROL-70 payload is not publicly disclosed to protect sensitive information related to U.S. national security interests.


The Delta IV Heavy's retirement is a bittersweet moment. Its legacy is not just in the missions it has carried out but also in the inspiration it has provided for future innovations in space technology.
As we bid farewell to the Delta IV Heavy, the NROL-70 mission stands as a beacon of progress, a symbol of the unyielding human spirit to explore and secure the final frontier.