NASA has quietly killed the Exploration Upper Stage. A procurement notice on sam.gov reveals NASA intends to sole-source next-generation upper stages for SLS Artemis IV and V from United Launch Alliance, bypassing the in-house EUS program entirely.
The EUS was designed to boost SLS Block 1B's payload capacity beyond low Earth orbit. Its cancellation signals NASA is outsourcing a core propulsion component rather than developing it internally, a structural shift in how the agency builds its flagship rocket.
The full article is worth reading for what the procurement language reveals about the timeline, cost implications, and what ULA's involvement means for SLS's future as a competitive launch system.
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