CROSSROADS and the 58th Wing of the Fourth Air Force was designated Headquarters, Task Group 1.5 (Provisional).° From this organization came the staff for the test group. The 509th Composite Group and Roswell Army Air Field transferred to the Fourth Air Force from the Second, IT. It had dropped the two atomic bombs on Japan during World War The S8th Wing then transferred from March Field, California, to Roswell, There an intensive training program was instituted. Each unit concentrated on its special mission, with the highest priority being given to the bombing aircraft unit, the 393rd Bombardment Squadron. Bombing ranges near Albuquerque and Alamogordo were used heavily and Clovis Amy Air Field as a satellite trainiiig field for Task Group 1.5 (Provisional) where the world's first atomic cloud sampling was in preparation with drone aircraft, 1 Sampling CROSSROADS Operation CROSSROADS saw the beginning of Air Force atomic cloud sampling with drones because of the unknown dangers. Manhattan Project sampling requirements included tiny portions of the debris contained in the atomic cloud which represented what was actually contained in the cloud, One of the biggest worries for the scientists at that time was that fractionatj{on would take place, Fractionation was thephysical change in the distribution of debris particles collected andcould give false impression of what the cloud contained, "with no experience to fall back on," William Rubinson, a Los Alamos scientist, wrote, "All that one can do is to collect as many different samples in as many places and as many ways as possible, and devise what means he can h SWEH~2-003h 4> “(see