WASHINGTON — A United Launch Alliance Atlas 5 rocket featuring a new variant lifted off Dec. 12 from Vandenberg Air Force Base, California, carrying a classified payload for the U.S. National Reconnaissance Office.
The launch of the NROL-35 mission occurred at 7:13 p.m. local time, according to the NRO, which buys and operates U.S. spy satellites. Almost all NRO missions are classified, which means few details are released.
Denver-based ULA said the launch marked the first use of a new variant of the RL-10 engine, dubbed RL-10C, to power the Atlas 5 Centaur upper stage. The engine, supplied by Aerojet Rocketdyne, was originally designed for use on ULA’s Delta 4 rocket but was converted for the Atlas 5.
“ULA is extremely pleased with this first flight of the new, RL10C-1 engine,” Jim Sponnick, ULA’s vice president of Atlas and Delta programs, said in a Dec. 13 press release. “We have been working closely with Aerojet Rocketdyne and our Air Force customers for several years to develop and extensively test this next-generation engine to enable the most reliable and cost-effective upper stage propulsion for our Atlas and Delta programs.”
The rocket also included four solid-fuel strap-on motors.
NROL-35 was the NRO’s third launch in 2014 and only mission from Vandenberg, the agency said. The next NRO mission is expected to launch in spring 2015, the agency said.