This document consists of 75 pages, qe Kof8 of 70 copies, Series A » WI-929. OPERATION CASTLE—PROJECT 6.6 Report to the Scientific Director EFFECTS OF NUCLEAR DETONATIONS ON THE IONOSPHERE Fred B. Daniels Arthur K, Harris Evans Signal Laboratory Signal Corps Engineering Laboratories Fort Monmouth, New Jersey APRIL 1957 — U. S. MILITARY AGENCIES MAY COTIIN O°PI=S CF THIS REPORT DIRECTLY @ 1"! FROM DDC. OTHER QUALIFIED USLRS Swinuk REQUEST THROUGH _‘5 ONSgy Boerne v (\ daogsia| u 8 Darscter Defense Ltomic Surport Avency ‘Washington, Dd. C. 20501 inne ths Nationas sani of tha + TO po wt in Fes and 194. 7 a? tty corbonta in any yelee eek OU “a Unitecee Te peamer LO) 2) yocuabited by Law. # aww FORMIRLY RESTRICTED DATA oF _. USASRPA Ninel] SCL mene Exeleded from quteme ts Gown recina ead santas Hance AS NESTALICIED DATA LI PORSTGN DISSEMING GAG SLCTION 144b, At _ EASSIE ant \ * p