test towers have been extended to 500 feet, and during Operation Plumbbob (Spring 1957) there will be at least cne 700-foot tower. Also, Exten- a new technique of using captive balloons is being developed. sive tasis are being conducted to determine the feasibility of detonatizg puclear devices so far underground that all of the radicactive material will remain captured and thus, of ccurse, conpletely eliminate any fallout. Prior to each nuclear detonation a "warning circle" is established for aircraft, designed to provide control of aerial flights within the area of predicted path of the atomic cioud. A representative of the Civil Aercnautics Administration is assigned to the test organization and assists in establishing the controlled area. This may typically extend = about 150 tiles in radius ani be in force for a period from about H minus ome-"alf hour to H rlus 10 hours. All aircraft are required to check throigh the Civil Aercnautics Administration before flying in 3. 1 4 umti: it ls no longer readily detectable. 4t faa APTer ach watlear Durst, aircraft from the Test Crganmization Behind this come Tiss aiveralrl 7. iit the fallout pattern on the grouna. ~~ This > é TZ Tiegite senlterto is - Pe igsin 2 ET - (Sering Lif 7) ilbustreres tle excensive system organized mot only to Take funir ris raiicicgizal uensureme ¢ with the citizens of nearvy communities. ~ fis. wo provide cltse ifeices The Atomic Energy Commission and the U. 5. Public Health Service jointly organized a program wherein the areas around the test site are mapped out into 17 zczes. caliy qualified man has been assigned to live in eact: zone. - 32 - * A techniHis duties

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