Aerial reconnaissance
Some of the sandbags dropped by the "fusen bakudan" were taken to the Military Geology Unit of the United States Geological Survey for investigation. Working with the Military Intelligence Service, the researchers of the Military Geological Unit began microscopic and chemical examination of the sand from the sandbags to determine types and distribution of diatoms and other microscopic sea creatures, and its mineral composition. The geologists ultimately determined that the sand had been taken from the vicinity of Ichinomiya. Aerial reconnaissance then located two of the hydrogen production plants nearby, which were soon destroyed by B-29 bombing raids in April 1945.