The development of overhead reconnaissance technology is one of the most important – if not the most important – advances in the history of intelligence. Policymakers today use IMINT from spy planes and satellites in their daily assessments of global threats, but did you know that overhead reconnaissance technology predates the advent of powered flight? SPY Historian Vince Houghton is joined by Dr. Jim Green, Director of the Planetary Science Division at NASA, to discuss Civil War balloon reconnaissance. Dr. Green, an expert in the field, explains the role of balloons in the greater Union strategy, their impact on the war effort, and the numerous and significant innovations developed by Union “aeronauts” (including the first aircraft carriers!). This interview took place May 30, 2014