The U.S. Air Force contends United Launch Alliance needs as many as 22 RD-180 rocket engines to compete against SpaceX for dozens of national security launches that start going out for bid later this year, according to a U.S. senator.

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Mike Gruss is the chief content and strategy officer at SpaceNews. From 2013 to 2016 he was a senior reporter at SpaceNews covering military space. Previously, he was editor in chief of Sightline Media Group and worked as a reporter and columnist for...