By Joey Roulette
WASHINGTON (Reuters) -Northrop Grumman is partnering with rocket startup Firefly Aerospace to build a core stage for its workhorse Antares rocket to replace Russian-made engines that were cut off from the United States after the invasion of Ukraine, the company said on Monday.
The new version of Antares, a rocket which NASA uses to ferry cargo to the International Space Station, will use seven Miranda engines under development by launch startup Firefly, Northrop said in a statement, adding that the two companies will later work on an entirely new launch vehicle.
“Through our collaboration, we will first develop a fully domestic version of our Antares rocket, the Antares 330, for Cygnus space station commercial resupply services, followed by an entirely new medium class launch vehicle,” Scott Lehr, vice president of Northrop’s launch and missile defense unit, said in a press release.
The Antares rocket launches Northrop’s Cygnus cargo spacecraft to the space station.
Northrop’s statement did not specify the value of the partnership or when it expects to launch the new Antares 330 rocket. Northrop and Austin, Texas-based Firefly did not immediately respond to follow-up questions.
Northrop’s partnership with Firefly comes months after Russia halted deliveries of Antares’ original RD-181 engines in retaliation for sanctions the U.S. levied on Moscow over its Feb. 24 invasion of Ukraine. The delivery halt left Northrop with just two remaining Antares rockets despite several more under contract with NASA.
A pair of RD-181 engines have long powered the Antares rocket. Northrop previously said it was exploring other rockets for Cygnus after Russia’s decision to cut off engine deliveries.
Significant changes to a rocket’s core stage could take years to complete. It was unclear whether Northrop plans to launch Cygnus aboard other potentially available rockets, such as SpaceX’s Falcon 9, while Antares 330 is under development.
(Reporting by Joey Roulette; Editing by Rosalba O’Brien, David Gregorio and Leslie Adler)


