tl;dr: NASA has quietly removed SR-71A Tail No. 844 from its display pole at Armstrong Flight Research Center and is attempting to return the Blackbird to flight after a 27-year hiatus, recruiting retired test engineers for the secret project. The effort faces enormous hurdles: the $600M spare parts inventory was destroyed in 2007, specialized JP-7 fuel and ground equipment are gone, and the engines have sat unlubricated for decades. NASA Administrator Jared Isaacman teased the project at a September summit as part of a broader push to rebuild the agency's X-plane fleet.