EUSure It's a Centaur - The Flame Trench

Why It Matters

Replacing the ICPS with Centaur 5 accelerates Artemis’s launch cadence and cuts costs, while the cancellation of congressionally mandated hardware reshapes NASA’s procurement landscape and impacts future SLS development.

Key Takeaways

• NASA cancels Exploration Upper Stage and Mobile Launcher 2 for Artemis
• Centaur 5 will replace ICPS as upper stage starting Artemis 4
• Decision driven by need for 10‑12 month launch turnaround
• Contract uses JOF justification, bypassing competitive procurement process
• ML2 may be repurposed despite cancellation, hardware still 90% complete

Summary

The Flame Trench episode focused on NASA’s abrupt restructuring of the Artemis launch architecture. Within hours of the show’s start, the network confirmed that both the Exploration Upper Stage (EUS) and Mobile Launcher 2 (ML2) – originally mandated by Congress – are being removed from the Artemis 4 and later flight plans, with the Centaur 5 upper stage slated to replace the Interim Cryogenic Propulsion Stage (ICPS).

The hosts explained that the shift aims to streamline operations and achieve a 10‑12‑month turnaround between lunar missions, using a standardized SLS configuration. NASA issued a Justification for Other Than Full and Open Competition (JOF) to procure Centaur 5 directly, sidestepping the usual competitive process and effectively overturning the congressional mandates that had driven the EUS/ML2 contracts.

Panelists highlighted the technical ramifications: Centaur 5, already flying on ULA’s Vulcan, fits the existing SLS Block 1 dimensions more closely than the larger EUS, requiring only modest adapter modifications rather than a complete redesign of the mobile launcher. They also debated whether the 90 %‑complete ML2 structure might be repurposed for a future Block 1B variant, noting that scrapping it would waste significant resources.

The decision signals a faster, potentially cheaper path to sustained lunar flights but raises questions about contract compliance, hardware waste, and the long‑term flexibility of the SLS family. Industry observers will watch how quickly NASA can integrate Centaur 5 and whether the abandoned hardware can be salvaged for future missions.

Original Description

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