NASA definitively terminates Boeing's Exploration Upper Stage project for lunar rocket SLS

The American space agency NASA has made a radical and final decision to terminate the long-running, problematic advanced upper stage project Exploration Upper Stage (EUS), developed by the Boeing corporation for the flagship lunar rocket Space Launch System (SLS). The news of the definitive end of work on EUS, based on sources within the agency, was first reported by the Ars Technica portal. This decision results in the official closure of a chapter that for years constituted a bottleneck for the entire Artemis lunar program. The Artemis program, officially announced in 2017, is the successor to the legendary Apollo program of the 1960s and 70s. Its goal is not only to return humans to the Moon but also to establish a sustained presence through the construction of the Gateway orbital station and a surface base, which requires regular, advanced supply and crewed missions. The direct cause of this radical change were chronic delays and uncontrolled cost overruns of the EUS project. This stage was essential for missions Artemis IV and beyond, as it was to provide significantly greater payload capacity and trajectory precision than the currently used interim Interim Cryogenic Propulsion Stage (ICPS). In response, NASA turned to the commercial sector, where proven technologies are already available. As reported by Bloomberg and Reuters agencies, NASA selected a solution from the consortium United Launch Alliance (ULA). It involves delivering a modified version of the Vulcan Centaur rocket, which is to serve as the upper stage for heavier variants of the SLS rocket, known as Block 1B. NASA's decision signifies a fundamental change in the architecture of the Artemis program and marks a clear departure from the traditional contracting model in favor of ready-made commercial solutions. The interim ICPS stage, derived from Delta IV program surplus and used in Artemis I, II, and III missions, will remain in use longer than initially planned. The new solution from ULA is intended to enable the execution of advanced missions without further catastrophic delays that threatened the entire program. However, complex integration of systems from two different platforms will be necessary – the monumental, government-developed SLS rocket and the smaller, commercial Vulcan Centaur. „The long-running Exploration Upper Stage project, which was to be an advanced upper stage for NASA's Moon rocket, has finally been terminated.” — Eric Berger, journalist for Ars Technica, who first reported the news of the EUS project termination The termination of the EUS project is another major failure for Boeing in NASA's lunar program. The company, being the main contractor for the SLS rocket's core stage, failed to deliver a key component, despite years of work and billions of dollars in funding. Meanwhile, its partner in the ULA consortium, Lockheed Martin, has succeeded by delivering the Orion spacecraft, and now also the Vulcan rocket, which will take over the functions of the abandoned stage. Ironically, Boeing, a co-owner of ULA, has failed as the primary contractor but may benefit indirectly through its stake in the company that won the new contract. NASA's decision also underscores the growing role of the commercial space sector, represented by companies such as SpaceX and ULA, which offer faster and cheaper solutions than traditional, large defense contractors.