4.8 OPERATION IVY.
IVY, conducted at Enewetak Atoll during autumn 1952, consisted of two
detonations.
These two detonations, identified in the following table, were
the largest nuclear explosions up to that time:
Event
Date
Type
Yield
10.4 megatons
MIKE
1 November
Surface
KING
16 November
Airdrop
500 kilotons
The description of the MIKE detonation by the author of History--Task
Group 132.1 and reproduced in History of Operation IVY bears repeating
(10: 1,187):
The Shot, as witnessed aboard the various vessels at
sea, is not easily described. Accompanied by a
brilliant light, the heat wave was felt immediately at
distances of thirty to thirty-five miles. The
tremendous fireball, appearing on the horizon like the
sun when half-risen, quickly expanded after a momentary
hover time and appeared to be approximately a mile in
diameter before the cloud-chamber effect and scud clouds
partially obscured it from view. A very large cloudchamber effect was visible shortly after the detonation
and a tremendous conventional mushroom-shaped cloud soon
appeared, seemingly balanced on a wide dirty stem.
Apparently, the dirty stem was due to the coral
particles, debris, and water which were sucked high into
the air. Around the base of the stem, there appeared to
be a curtain of water which soon dropped back around the
area where the island of Elugelab [Eluklab] had been.
Figure 10 presents a photograph of the MIKE cloud (C).
4.8.1
Background and Objectives of Operation IVY.
President Truman made the decision to pursue the development of thermo-
nuclear weapons in 1950.
Operation GREENHOUSE was an initial step toward this
end, as section 4.5 explains.
Operation IVY considerably extended the
94