Sean Duffy

Sean Duffy served as acting NASA Administrator and publicly confirmed that each SLS launch costs approximately $4 billion, a figure that has become central to the debate about whether the rocket's continued operation can be justified.

His public confirmation of the $4bn figure was significant because previous NASA communications had been ambiguous about the fully loaded per-flight cost. The acknowledgement gave critics of the programme a concrete number to anchor their arguments for commercial alternatives.

Duffy's acting role placed him at the interface between congressional budget politics — where SLS has strong support — and an administration philosophically aligned with commercial spaceflight. Navigating that tension without a confirmed administrator was a defining feature of the early 2026 Artemis debate.