NASA Cancels Exploration Upper Stage; ULA Centaur V Selected

NASA announced the cancellation of the Exploration Upper Stage and the SLS Block 1B and Block 2 upgrade programs. SLS will continue in a standardized Block 1 configuration. NASA confirmed a contract with United Launch Alliance to use the Centaur V as a replacement upper stage for future SLS flights, formally confirmed by contract on March 7, 2026. This ended Boeing's multi-year EUS development program and wrote off approximately $2.8 billion in development investment.