In the midst of the growing debate over Zeus ' abilities , the US conducted its first high yield , high altitude tests – Hardtack Teak on 1 August 1958 , and Hardtack Orange on 12 August . These demonstrated a number of previously unknown or underestimated effects , notably that nuclear fireballs grew to very large size and caused all of the air in or immediately below the fireball to become opaque to radar signals , an effect that became known as nuclear blackout . This was extremely worrying for any system like Zeus , which would not be able to track warheads in or behind such a fireball , including those of the Zeus ' own warheads
Hardtack Teak
Hardtack Teak
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