: Test Aircraft Unit. 128 The Test Aircraft Unit, comprised of six ele- ments, exercised operational control over all test aircraft aud was responsible for briefing all aircrews involved in test projects. Command of the Test Aircraft Unit was assumed by Colonel jlden G, Thompson. The six elements, their compositions, and their missions are des= cribed in the following paragraphs. The Sampling clement was composed of the 4926th Test squadron (Sampling), Kirtland Air Force Base, augmented by personnel from the 4025th Strategic Reconnaissance Squadron, 4080th Strategic reconnaissance ding, Strategic Air Comnand, The element conducted nuclear cloud sampling with ten o=57B aircraft provided by the Air Research and Develosment Comnand and six B-57D aircraft provided by Strategic Air Command. Sampling requirements for HARVTACK, as specified by Air Force and by Los Alamos Scientific Laboratory and University of California sxadiation Laboratory, made necessary a number of samples ranging from one to ten (depending upon che nature of each shot), coilected at various altitudes, A sample consisted of a predetermined amount of radioactive material, generated from the detonation of a nuclear device, coilected on a special filter paper or in gas bottles, After return of each aim craft from the sampling mission, the filter vapyer and gas bottles were removed from tne aircraft and procesved for i:mediate shivment to itomic wnergy voinmission laboratories in tne Zone of Interior ivr radio-cneuical AFWL/ iQ — analysis,