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THE TRINITY TEST
(Trinity Test Site, July 16, 1945)
Events >
Dawn of the Atomic Era, 1945
- The War Enters Its Final
Phase, 1945
- Debate Over How to Use the
Bomb, Late Spring 1945
- The Trinity Test, July 16,
1945
- Safety and the
Trinity Test, July 1945
- Evaluations of
Trinity, July 1945
- Potsdam and the
Final Decision to Bomb, July 1945
- The Atomic Bombing of
Hiroshima, August 6, 1945
- The Atomic Bombing of
Nagasaki, August 9, 1945
- Japan Surrenders, August
10-15, 1945
- The Manhattan Project and
the Second World War, 1939-1945
Until
the atomic bomb could be tested, doubt would remain about its
effectiveness. The world had never seen a nuclear explosion
before, and
estimates varied widely on how much energy would be released.
Some scientists at Los Alamos
continued
privately to have doubts that it would work at all. There was
only enough
weapons-grade uranium available for one bomb, and confidence in the gun-type
design was high, so on July 14, 1945, most of the uranium bomb
("Little
Boy") began its trip westward to the Pacific without its design having
ever
been fully tested. A test of the plutonium bomb seemed vital,
however, both to
confirm its novel implosion design
and to gather data on
nuclear explosions in general. Several plutonium bombs were now
"in the
pipeline" and would be available over the next few weeks and
months. It was therefore decided to test one of these.
Robert Oppenheimer chose to name
this
the "Trinity" test, a name inspired by the poems of John Donne.
The
site chosen was a
remote corner on the Alamagordo Bombing Range
known as
the "Jornada del Muerto," or "Journey of Death," 210 miles south of Los
Alamos. The
elaborate instrumentation surrounding the site was tested with an
explosion of a
large amount of conventional explosives on May 7. Preparations
continued throughout May and June and were
complete by the beginning of July. Three observation bunkers
located
10,000 yards north, west, and south (right) of the firing tower at
ground zero would
attempt to measure key aspects of the reaction. Specifically,
scientists would try to determine the symmetry of the implosion and the
amount
of energy released. Additional measurements would be taken to
determine
damage estimates, and equipment would record the behavior of the fireball.
The biggest concern was control of
the radioactivity the test device would release. Not
entirely content to trust favorable meteorological conditions
to carry the radioactivity into the upper atmosphere, the Army stood
ready to
evacuate the people in surrounding areas.
On July
12, the plutonium core was taken to the test area in an army
sedan (left). The non-nuclear components left for the test site
at 12:01 a.m.,
Friday the 13th. During the day on the 13th, final assembly of
the "Gadget" (as it was nicknamed) took place in the McDonald ranch
house. By 5:00 p.m. on the 15th, the
device had been assembled and hoisted atop the 100-foot firing
tower. Leslie Groves, Vannevar Bush, James Conant, Ernest Lawrence, Thomas Farrell, James Chadwick, and others
arrived in the test area, where it was pouring rain.
Groves and Oppenheimer, standing at the S-10,000 control bunker,
discussed what to do if
the weather did not break in time for the scheduled 4:00 a.m.
test. To
break the tension, Fermi began offering anyone listening a wager on
"whether or not the
bomb would ignite the atmosphere, and if so, whether it would merely
destroy New
Mexico or destroy the world." Oppenheimer himself had bet ten dollars
against George Kistiakowsky's entire month's pay that the bomb would
not work at
all. Meanwhile, Edward Teller was making everyone nervous by
applying
liberal amounts of sunscreen in the pre-dawn darkness and offering to
pass it
around. At 3:30, Groves and Oppenheimer pushed the time back to
5:30. At 4:00, the rain stopped. Kistiakowsky and his team armed the
device shortly after 5:00 and retreated
to S-10,000. In accordance with his policy that each observe from
different locations in case of an accident, Groves left Oppenheimer and
joined
Bush and Conant at base camp. Those in shelters heard the
countdown over
the public address system, while observers at base camp picked it up on
an FM radio signal.
During
the final seconds, most observers laid down on the ground with their
feet facing the Trinity site and simply waited. As the countdown
approached one minute, Isidore Rabi said to the man lying next to him,
Kenneth
Griesen, "Aren't you nervous?" "Nope" was Griesen's
reply. As Groves later wrote, "As I lay there in the final
seconds, I
thought only of what I would do if the countdown got to zero and
nothing
happened." Conant said he never knew seconds could be so
long.
As the countdown reached 10 seconds, Griesen suddenly blurted out to
his neighbor
Rabi, "Now I'm scared." Three, two, one, and Sam Allison cried
out, "Now!"
At
precisely 5:30 a.m. on Monday, July 16, 1945, the nuclear age began.
While Manhattan Project staff members watched anxiously, the device
exploded over the
New Mexico desert, vaporizing the tower and turning the asphalt around
the base of
the tower to green sand. Seconds after the explosion came a huge blast
wave and heat searing out across
the desert. No one could
see the radiation generated by
the explosion, but they all knew
it was there. The steel container
"Jumbo," weighing over 200 tons and transported to the desert only to
be eliminated from the test, was knocked ajar even though it stood half
a mile
from ground zero. As the orange and yellow fireball
stretched up and spread, a second column, narrower than the first, rose
and
flattened into a mushroom shape, thus providing the atomic age
with a visual
image that has become imprinted on the human consciousness as a symbol
of power and awesome destruction.
The most common immediate reactions to the
explosion were
surprise, joy, and relief. Lawrence was stepping from his car
when,
in his words, everything went "from darkness to brilliant sunshine in
an
instant"; he was "momentarily stunned by the surprise." (Click here to read Lawrence's thoughts on
the Trinity test.) A
military man was heard to exclaim, "The
long-hairs have let it get away from them!" Hans Bethe , who
had been looking directly at the explosion, was completely blinded for
almost
half a minute. Norris Bradbury reported that "the atom bomb did
not
fit into any preconceptions possessed by anybody." The blast wave
knocked Kistiakowsky (who was over five miles away) to the
ground. He quickly scrambled to his feet and
slapped Oppenheimer on the back, saying, "Oppie, you owe me ten
dollars." The
physicist Victor Weisskopf reported that "our first feeling was one of
elation." The word Isidor Rabi used was "jubilant." Within
minutes, Rabi was passing around a bottle of whiskey. At base
camp, Bush, Conant, and Groves
shook hands. Rabi reported watching Oppenheimer arrive at base
camp after the test:
You've seen pictures of Robert's hat. And he
came to where we were in the headquarters, so to speak. And his
walk was like "High Noon" -- I think it's the best I could describe it
-- this kind of strut. He'd done it.
When
they met, Groves said to Oppenheimer, "I am
proud of you." Groves's assistant, Thomas Farrell, remarked to
his
boss that "the war is over," to which Groves replied, "Yes, after
we drop two bombs on Japan." (Click here to
read Groves's observations of the Trinity test [pdf].) Probably
the most mundane response of
all was Fermi's: he had calculated ahead of time how far the blast
wave might displace small pieces of paper released into it. About
40
seconds after the explosion, Fermi stood, sprinkled his pre-prepared
slips of paper into the
atomic wind, and estimated from their deflection that the test had
released energy equivalent to 10,000
tons of TNT. The actual result as it was finally calculated --
21,000 tons (21 kilotons) -- was more than twice what Fermi had
estimated with this experiment and four
times as much as had been predicted by most at Los
Alamos.
Soon
shock and euphoria gave way to more sober
reflections. Rabi reported that after the initial euphoria, a
chill soon set in
on those present. The test director, Kenneth Bainbridge, called
the explosion a
"foul and awesome display" and remarked to Oppenheimer,
"Now we are all sons of bitches." Expressions of horror and
remorse are especially common in the later writings of those who were
present.
Oppenheimer wrote that the experience called to his mind the legend of
Prometheus, punished by Zeus for giving man fire, and said also that he
thought
fleetingly of Alfred Nobel's vain hope that dynamite would end
wars. Most
famously, Oppenheimer later recalled that the explosion had
reminded him of a line from the Hindu holy text, the Bhagavad-Gita:
"Now I am become Death, the
destroyer of worlds." The terrifying destructive power of atomic
weapons and the uses to which they might
be put were to haunt many of the Manhattan
Project scientists for the remainder of their lives.
The success of the
Trinity test meant that both types of bombs
-- the uranium design, untested but thought to be reliable, and the
plutonium
design, which had just been tested successfully -- were now available
for use in the war
against Japan. Little Boy, the uranium bomb, was dropped first at
Hiroshima on
August 6, while the plutonium weapon, Fat Man, followed three days
later at Nagasaki on August
9. Within days, Japan
offered to surrender.
- The War Enters Its Final
Phase, 1945
- Debate Over How to Use the
Bomb, Late Spring 1945
- The Trinity Test, July 16,
1945
- Safety and the
Trinity Test, July 1945
- Evaluations of
Trinity, July 1945
- Potsdam and the
Final Decision to Bomb, July 1945
- The Atomic Bombing of
Hiroshima, August 6, 1945
- The Atomic Bombing of
Nagasaki, August 9, 1945
- Japan Surrenders, August
10-15, 1945
- The Manhattan Project and
the Second World War, 1939-1945
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Sources and notes for this page.
The text for this page was adapted from,
and portions were taken directly from the Office of History and
Heritage Resources publication: F.
G. Gosling, The Manhattan Project: Making the Atomic Bomb
(DOE/MA-0001; Washington: History Division, Department of Energy,
January 1999), 48-49. On the availability of additional
plutonium bombs (but not uranium), see "The
Manhattan Engineer District, 1945-1946." The "long-hairs"
remark is quoted in Los Alamos
Scientific Laboratory, Los Alamos: Beginning of an Era, 1943-1945
(Los Alamos: Public Relations Office, Los Alamos Scientific Laboratory,
ca. 1967-1971), 53; the anecdotes re the final seconds of the
countdown are from Los Alamos: Beginning of an Era,
50-51. Click here for
information on the color photograph of Trinity. The
photograph of SED Herb Lehr holding the Gadget's core is courtesy the Los Alamos National Laboratory (LANL)
and is reprinted in Rachel Fermi and Esther Samra, Picturing the
Bomb: Photographs from the Secret World of the Manhattan Project (New
York: Harry N. Abrams, Inc., Publishers, 1995), 138. The
following pictures are also courtesy LANL: the bunker at S-10,000, the
plutonium core being unloaded from the car, the
gadget being hoisted up the tower, the unidentified man sitting next to
the gadget, and the photograph of Kenneth Bainbridge. The map of
the Trinity Test Site is reproduced from Vincent C. Jones, Manhattan:
The Army and the Atomic Bomb, United States Army in World War II
(Washington: Center of Military History, United States Army, 1988),
479. The photograph of Robert
Oppenheimerwith Leslie Grovesat
the Trinity Site appears on the cover of the History Office
publication: The
Signature Facilities of the Manhattan Project (Washington: History
Division, Department of Energy, 2001). The photograph of
Fat Man is courtesy the U.S. Army Corps of Engineers (via the National Archives).
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