ERIC BERGER: Blue Origin’s powerful BE-4 engine is more than four years late—here’s why.

The BE-4’s delayed development has, increasingly, been the subject of keen interest. This is partly because ULA has been working on its new Vulcan rocket for a number of years, and that rocket is important to the future of the company. The military is also eager for this delivery, as ULA is a primary provider of launch services to the Department of Defense alongside SpaceX. They hope Vulcan provides lower cost launch services with engines manufactured in the United States. Finally, many in the space community are genuinely curious about the cause of the delay.

Despite this widespread interest, however, Blue Origin has said almost nothing publicly about the engine development. Therefore, this story attempts to provide some context for why the BE-4 engines are late. It is based on anonymous sources at the company’s headquarters as well as industry officials, some of whom would likely be fired if they were named.

In response to questions for this article, a spokeswoman for Blue Origin, Linda Mills, offered only a single-sentence reply. “We’re on track to deliver the engines this year,” she said.

I certainly hope so — ULA and our military launch capacity have a lot riding on BE-4.

More great space reporting from Berger so do read the whole thing.