Projects Sign & Grudge

The first studies. Sign's "Estimate of the Situation" said interplanetary. It was burned.

Project Sign (1948) was the Air Force's first serious look; its staff produced an Estimate of the Situation concluding the objects were interplanetary. General Vandenberg rejected it for lack of proof and the document was ordered burned — its existence confirmed by Blue Book's own chief, Ruppelt, in his 1956 memoir. Sign was replaced by Grudge, whose name described its methodology. The episode matters structurally: the earliest institutional conclusion was the extraordinary one, and the correction was administrative, not evidentiary.