← Chronicle · Succession · December 18, 2025

Sean Duffy's Acting NASA Role Ends as Jared Isaacman Is Confirmed

Sean Duffy wore two hats through much of 2025: confirmed Secretary of Transportation from January 28, 2025, and acting Administrator of NASA alongside it. The second hat came off on December 18, 2025, when Jared Isaacman was confirmed as NASA Administrator in his own right.

Duffy’s Transportation mission — air traffic control modernization and the department’s infrastructure program — continued unchanged; the change closed a dual-role arrangement that this site’s roster audit later flagged because the Department of Transportation’s own biography page kept describing the NASA role in the present tense after it had ended. Isaacman leads NASA through the Artemis program this chronicle tracks (see the August 28, 2026 Space Medal of Honor and space station entries).

Sources: Banked research in this site’s files (research cluster B): Duffy’s NASA acting role ended December 2025; Isaacman confirmed December 18. Department of Transportation.