A United Launch Alliance (ULA) Delta IV Heavy rocket lifted a National Reconnaissance Office (NRO) classified payload to orbit for the NRO Launch-82 (NROL-82) mission on Apr. 26.

The launch from Vandenberg AFB, Calif. was the first U.S. Space Force (USSF) National Security Space Launch (NSSL) this year and the NRO’s 18th mission from Vandenberg since 2006, per USSF’s Space and Missile Systems Center (SMC).

The NRO has relied on the Delta IV Heavy rocket for lofting the agency’s weightiest satellites into orbit.

ULA is a partnership between Boeing [BA] and Lockheed Martin [LMT].

Col. Robert Bongiovi, the director of SMC’s Launch Enterprise, said in a statement that the launched NRO payload “is one of the most complex payloads our nation launches, and it provides vital space capability.”

“It is a testament to the skill and dedication of our team to have successfully placed 85 of 85 national security payloads in orbit,” said Col. Erin Gulden, chief of the Atlas and Delta Division of SMC’s Launch Enterprise.

Northrop Grumman [NOC] said that it supported ULA in the Apr. 26 launch, as the company builds the Delta IV Heavy’s 11 large composite structures, including three thermal shields that protect the engine during flight; three centerbody structures that connect the liquid oxygen and liquid hydrogen tanks; the payload fairing to shield the payload; the composite interstage on the center common booster core; the nose cones on the two strap-on boosters and one set of X-panel structures that link the upper stage liquid oxygen tank with the upper stage hydrogen tank; the nozzles on the three Aerojet Rocketdyne [AJRD] RS-68 engines; and the nozzles’ thermal protection material to protect them from temperatures which can reach more than 4,000 degrees Fahrenheit during launch.

Under NSSL, the Air Force is to end reliance on the Russian-made RD-180 engine by leveraging U.S. commercial launch capabilities. The RD-180 powers ULA’s Atlas V rocket. The Air Force has 12 RD-180 engines it can use if a catastrophic failure arises in the NSSL program, but the service is prohibited by law from buying new RD-180s after 2022.

Both Northrop Grumman and Blue Origin lost out in the Phase 2 launch service procurement NSSL awards last Aug. 7 when SMC and the NRO awarded ULA $337 million for two classified mission launches and SpaceX a $316 million contract for one classified mission launch.

In January, the Air Force said it ended the Launch Service Agreement Other Transaction Authority (LSA OTA) agreements with Northrop Grumman and Blue Origin last Dec. 31 and paid the companies $787.2 million–$531.7 million to Northrop Grumman and $255.5 million to Blue Origin–for meeting milestones in the companies’ development of their rockets– OmegA for Northrop Grumman and New Glenn for Blue Origin (Defense Daily, Jan. 22).

Congressional appropriators have been concerned with the cost of NSSL, as the Evolved Expendable Launch Vehicle (EELV) program, the predecessor to NSSL, had as its paramount goal a dramatic reduction in launch costs through lower cost commercial launch providers. SpaceX’s Falcon 9 and Falcon Heavy launches start around $60 million but will cost no more than $150 million, SpaceX founder Elon Musk has said.

Blue Origin is owned by Amazon [AMZN] founder Jeff Bezos, who also owns The Washington Post.