by the U.S. Department of Energy
National Atomic Museum,
Albuquerque, New Mexico
The First Atomic Test.
Schmidt-McDonald Ranch House.
The First Atomic Test
On Monday morning July 16, 1945, the world was changed forever when
the first atomic bomb was tested in an isolated area of the New Mexico
desert. Conducted in the final month of World War II by the top-
secret Manhattan Engineer District, this test was code named Trinity.
The Trinity test took place on the Alamogordo Bombing and Gunnery
Range, about 230 miles south of the Manhattan Project's headquarters
at Los Alamos, New Mexico. Today this 3,200 square mile range, partly
located in the desolate Jornada del Muerto Valley, is named the White
Sands Missile Range and is actively used for non-nuclear weapons
Before the war the range was mostly public and private grazing land
that had always been sparsely populated. During the war it was even
more lonely and deserted because the ranchers had agreed to vacate
their homes in January 1942. They left because the War Department
wanted the land to use as an artillery and bombing practice area. In
September 1944, a remote 18 by 24 square mile portion of the north-
east corner of the Bombing Range was set aside for the Manhattan
Project and the Trinity test by the military.
The selection of this remote location in the Jornada del Muerto Valley
for the Trinity test was from an initial list of eight possible test
sites. Besides the Jornada, three of the other seven sites were also
located in New Mexico: the Tularosa Basin near Alamogordo, the lava
beds (now the El Malpais National Monument) south of Grants, and an
area southwest of Cuba and north of Thoreau. Other possible sites not
located in New Mexico were: an Army training area north of Blythe,
California, in the Mojave Desert; San Nicolas Island (one of the
Channel Islands) off the coast of Southern California; and on Padre
Island south of Corpus Christi, Texas, in the Gulf of Mexico. The
last choice for the test was in the beautiful San Luis Valley of south-
central Colorado, near today's Great Sand Dunes National Monument.
Based on a number of criteria that included availability, distance
from Los Alamos, good weather, few or no settlements, and that no
Indian land would be used, the choices for the test site were narrowed
down to two in the summer of 1944. First choice was the military
training area in southern California. The second choice, was the
Jornada del Muerto Valley in New Mexico. The final site selection was
made in late August 1944 by Major General Leslie R. Groves, the
military head of the Manhattan Project. When General Groves
discovered that in order to use the California location he would need
the permission of its commander, General George Patton, Groves quickly
decided on the second choice, the Jornada del Muerto. This was
because General Groves did not want anything to do with the flamboyant
Patton, who Groves had once described as "the most disagreeable man I
had ever met."1 Despite being second choice the remote Jornada was
a good location for the test, because it provided isolation for
secrecy and safety, was only 230 miles south of Los Alamos, and was
already under military control. Plus, the Jornada enjoyed relatively
The history of the Jornada is in itself quite fascinating, since it
was given its name by the Spanish conquerors of New Mexico. The
Jornada was a short cut on the Camino Real, the King's Highway that
linked old Mexico to Santa Fe, the capital of New Mexico. The Camino
Real went north from Mexico City till it joined the Rio Grande near
present day El Paso, Texas. Then the trail followed the river valley
further north to a point where the river curved to the west, and its
valley narrowed and became impassable for the supply wagons. To avoid
this obstacle, the wagons took the dubious detour north across the
Jornada del Muerto. Sixty miles of desert, very little water, and
numerous hostile Apaches. Hence the name Jornada del Muerto, which is
often translated as the journey of death or as the route of the dead
man. It is also interesting to note that in the late 16th century,
the Spanish considered their province of New Mexico to include most of
North America west of the Mississippi!
The origin of the code name Trinity for the test site is also
interesting, but the true source is unknown. One popular account
attributes the name to J. Robert Oppenheimer, the scientific head of
the Manhattan Project. According to this version, the well read
Oppenheimer based the name Trinity on the fourteenth Holy Sonnet by
John Donne, a 16th century English poet and sermon writer. The sonnet
started, "Batter my heart, three-personed God."2 Another version of
the name's origin comes from University of New Mexico historian Ferenc
M. Szasz. In his 1984 book, The Day the Sun Rose Twice, Szasz quotes
Robert W. Henderson head of the Engineering Group in the Explosives
Division of the Manhattan Project. Henderson told Szasz that the name
Trinity came from Major W. A. (Lex) Stevens. According to Henderson,
he and Stevens were at the test site discussing the best way to haul
Jumbo (see below) the thirty miles from the closest railway siding to
the test site. "A devout Roman Catholic, Stevens observed that the
railroad siding was called 'Pope's Siding.' He then remarked that
the Pope had special access to the Trinity, and that the scientists
would need all the help they could get to move the 214 ton Jumbo to
its proper spot."3
The Trinity test was originally set for July 4, 1945. However, final
preparations for the test, which included the assembly of the bomb's
plutonium core, did not begin in earnest until Thursday, July 12. The
abandoned George McDonald ranch house located two miles south of the
test site served as the assembly point for the device's core. After
assembly, the plutonium core was transported to Trinity Site to be
inserted into the thing or gadget as the atomic device was called.
But, on the first attempt to insert the core it stuck! After letting
the temperatures of the core and the gadget equalize, the core fit
perfectly to the great relief of all present. The completed device
was raised to the top of a 100-foot steel tower on Saturday, July 14.
During this process workers piled up mattresses beneath the gadget to
cushion a possible fall. When the bomb reached the top of the tower
without mishap, installation of the explosive detonators began. The
100-foot tower (a surplus Forest Service fire-watch tower) was
designated Point Zero. Ground Zero was at the base of the tower.
As a result of all the anxiety surrounding the possibility of a
failure of the test, a verse by an unknown author circulated around
Los Alamos. It read:
From this crude lab that spawned a dud.
Their necks to Truman's ax uncurled
Lo, the embattled savants stood,
and fired the flop heard round the world.4
A betting pool was also started by scientists at Los Alamos on the
possible yield of the Trinity test. Yields from 45,000 tons of TNT to
zero were selected by the various bettors. The Nobel Prize-winning
(1938) physicist Enrico Fermi was willing to bet anyone that the test
would wipe out all life on Earth, with special odds on the mere
destruction of the entire State of New Mexico!
Meanwhile back at the test site, technicians installed seismographic
and photographic equipment at varying distances from the tower. Other
instruments were set up for recording radioactivity, temperature, air
pressure, and similar data needed by the project scientists.
According to Lansing Lamont in his 1965 book Day of Trinity, life at
Trinity could at times be very exciting. One afternoon while
scientists were busily setting up test instruments in the desert, the
tail gunner of a low flying B-29 bomber spotted some grazing antelopes
and opened up with his twin .50-caliber machine guns. "A dozen
scientists, ... under the plane and out of the gunner's line of
vision, dropped their instruments and hugged the ground in terror as
the bullets thudded about them."5 Later a number of these
scientists threatened to quit the project.
Workers built three observation points 5.68 miles (10,000 yards),
north, south, and west of Ground Zero. Code named Able, Baker, and
Pittsburgh, these heavily-built wooden bunkers were reinforced with
concrete, and covered with earth. The bunker designated Baker or
South 10,000 served as the control center for the test. This is where
head scientist J. Robert Oppenheimer would be for the test.
A fourth observation point was the test's Base Camp, (the abandoned
Dave McDonald ranch) located about ten miles southwest of Ground Zero.
The primary observation point was on Compania Hill, located about 20
miles to the northwest of Trinity near today's Stallion Range Gate,
off NM 380.
The test was originally scheduled for 4 a.m., Monday July 16, but was
postponed to 5:30 due to a severe thunderstorm that would have
increased the amount of radioactive fallout, and have interfered with
the test results. The rain finally stopped and at 5:29:45 a.m.
Mountain War Time, the device exploded successfully and the Atomic Age
was born. The nuclear blast created a flash of light brighter than a
dozen suns. The light was seen over the entire state of New Mexico
and in parts of Arizona, Texas, and Mexico. The resultant mushroom
cloud rose to over 38,000 feet within minutes, and the heat of the
explosion was 10,000 times hotter than the surface of the sun! At ten
miles away, this heat was described as like standing directly in front
of a roaring fireplace. Every living thing within a mile of the tower
was obliterated. The power of the bomb was estimated to be equal to
20,000 tons of TNT, or equivalent to the bomb load of 2,000 B-29,
After witnessing the awesome blast, Oppenheimer quoted a line from a
sacred Hindu text, the Bhagavad-Gita: He said: "I am become death,
the shatterer of worlds."6 In Los Alamos 230 miles to the north, a
group of scientists' wives who had stayed up all night for the not so
secret test, saw the light and heard the distant sound. One wife,
Jane Wilson, described it this way, "Then it came. The blinding light
no one had ever seen. The trees, illuminated, leaping out. The
mountains flashing into life. Later, the long slow rumble. Something
had happened, all right, for good or ill."7
General Groves' deputy commander, Brigadier General T. F. Farrell,
described the explosion in great detail: "The effects could well be
called unprecedented, magnificent, beautiful, stupendous, and
terrifying. No man-made phenomenon of such tremendous power had ever
occurred before. The lighting effects beggared description. The
whole country was lighted by a searing light with the intensity many
times that of the midday sun. It was golden, purple, violet, gray,
and blue. It lighted every peak, crevasse and ridge of the nearby
mountain range with a clarity and beauty that cannot be described but
must be seen to be imagined..."8
Immediately after the test a Sherman M-4 tank, equipped with its own
air supply, and lined with two inches of lead went out to explore the
site. The lead lining added 12 tons to the tank's weight, but was
necessary to protect its occupants from the radiation levels at ground
zero. The tank's passengers found that the 100-foot steel tower had
virtually disappeared, with only the metal and concrete stumps of its
four legs remaining. Surrounding ground zero was a crater almost
2,400 feet across and about ten feet deep in places. Desert sand
around the tower had been fused by the intense heat of the blast into
a jade colored glass. This atomic glass was given the name Atomsite,
but the name was later changed to Trinitite.
Due to the intense secrecy surrounding the test, no accurate
information of what happened was released to the public until after
the second atomic bomb had been dropped on Japan. However, many
people in New Mexico were well aware that something extraordinary had
happened the morning of July 16, 1945. The blinding flash of light,
followed by the shock wave had made a vivid impression on people who
lived within a radius of 160 miles of ground zero. Windows were
shattered 120 miles away in Silver City, and residents of Albuquerque
saw the bright light of the explosion on the southern horizon and felt
the tremor of the shock waves moments later.
The true story of the Trinity test first became known to the public on
August 6, 1945. This is when the world's second nuclear bomb,
nicknamed Little Boy, exploded 1,850 feet over Hiroshima, Japan,
destroying a large portion of the city and killing an estimated 70,000
to 130,000 of its inhabitants. Three days later on August 9, a third
atomic bomb devastated the city of Nagasaki and killed approximately
45,000 more Japanese. The Nagasaki weapon was a plutonium bomb,
similar to the Trinity device, and it was nicknamed Fat Man. On
Tuesday August 14, at 7 p.m. Eastern War Time, President Truman made a
brief formal announcement that Japan had finally surrendered and World
War II was over after almost six years and 60 million deaths!
On Sunday, September 9, 1945, Trinity Site was opened to the press for
the first time. This was mainly to dispel rumors of lingering high
radiation levels there, as well as in Hiroshima and Nagasaki. Led by
General Groves and Oppenheimer, this widely publicized visit made
Trinity front page news all over the country.
Trinity Site was later encircled with more than a mile of chain link
fencing and posted with signs warning of radioactivity. In the early
1950s most of the remaining Trinitite in the crater was bulldozed into
a underground concrete bunker near Trinity. Also at this time the
crater was back filled with new soil. In 1963 the Trinitite was
removed from the bunker, packed into 55-gallon drums, and loaded into
trucks belonging to the Atomic Energy Commission (the successor of the
Manhattan Project). Trinity site remained off-limits to military and
civilian personnel of the range and closed to the public for many
years, despite attempts immediately after the war to turn Trinity into
a national monument.
In 1953 about 700 people attended the first Trinity Site open house
sponsored by the Alamogordo Chamber of Commerce and the Missile Range.
Two years later, a small group from Tularosa, NM visited the site on
the 10th anniversary of the explosion to conduct a religious service
and pray for peace.
Regular visits have been made annually in recent years on the first
Saturday in October instead of the anniversary date of July 16, to
avoid the desert heat. Later Trinity Site was opened one additional
day on the first Saturday in April. The Site remains closed to the
public except for these two days, because it lies within the impact
areas for missiles fired into the northern part of the Range.
In 1965, Range officials erected a modest monument at Ground Zero.
Built of black lava rock, this monument serves as a permanent marker
for the site and as a reminder of the momentous event that occurred
there. On the monument is a plain metal plaque with this simple
inscription: "Trinity Site Where the World's First Nuclear Device Was
Exploded on July 16, 1945."
During the annual tour in 1975, a second plaque was added below the
first by The National Park Service, designating Trinity Site a
National Historic Landmark. This plaque reads, "This site possesses
national significance in commemorating the history of the U.S.A."
Lying next to the entrance of the chain link fence that still
surrounds Trinity Site are the rusty remains of Jumbo. Jumbo was the
code name for the 214-ton Thermos shaped steel and concrete container
designed to hold the precious plutonium core of the Trinity device in
case of a nuclear mis-fire. Built by the Babcock and Wilcox Company
of Barberton, Ohio, Jumbo was 28 feet long, 12 feet, 8 inches in
diameter, and with steel walls up to 16 inches thick.
The idea of using some kind of container for the Trinity device was
based on the fact that plutonium was extremely expensive and very
difficult to produce. So, much thought went into a way of containing
the 15 lb. plutonium core of the bomb, in case the 5,300 lbs. of
conventional high explosives surrounding the core exploded without
setting off a nuclear blast, and in the process scattering the costly
plutonium (about 250 million dollars worth) across the dessert. After
extensive research and testing of other potential containment ideas,
the concept of Jumbo was decided on in the late summer of 1944.
However, by the spring of 1945, after Jumbo had already been built and
transported (with great difficulty) to the Trinity Site by the
Eichleay Corporation of Pittsburgh, it was decided not to explode the
Trinity device inside of Jumbo after all. There were several reasons
for this new decision: first, plutonium had become more readily
(relatively) available; second, the Project scientists decided that
the Trinity device would probably work as planned; and last, the
scientists realized that if Jumbo were used it would adversely affect
the test results, and add 214 tons of highly radioactive material to
Not knowing what else to do with the massive 12 million dollar Jumbo,
it was decided to suspend it from a steel tower 800 yards from Ground
Zero to see how it would withstand the Trinity test. Jumbo survived
the approximately 20 kiloton Trinity blast undamaged, but its
supporting 70-foot tall steel tower was flattened.
Two years later, in an attempt to destroy the unused Jumbo before it
and its 12 million dollar cost came to the attention of a
congressional investigating committee, Manhattan Project Director
General Groves ordered two junior officers from the Special Weapons
Division at Sandia Army Base in Albuquerque to test Jumbo. The Army
officers placed eight 500-pound conventional bombs in the bottom of
Jumbo. Since the bombs were on the bottom of Jumbo, and not the
center (the correct position), the resultant explosion blew both ends
off Jumbo. Unable to totally destroy Jumbo, the Army then buried it
in the desert near Trinity Site. It was not until the early 1970s
that the impressive remains of Jumbo, still weighing over 180 tons,
were moved to their present location.
Schmidt-McDonald Ranch House
The Schmidt-McDonald ranch house is located two miles south of Ground
Zero. The property encompasses about three acres and consists of the
main house and assorted outbuildings. The house, surrounded by a low
stone wall, was built in 1913 by Franz Schmidt, a German immigrant and
homesteader. In the 1920s Schmidt sold the ranch to George McDonald
and moved to Florida.
The ranch house is a one-story, 1,750 square-foot adobe (mud bricks)
building. An ice house is located on the west side along with an 9'-
4" deep underground cistern. A 14 by 18.5 foot stone addition, which
included a modern bathroom, was added onto the north side in the
1930s. East of the house there is a large, divided concrete water
storage tank and a windmill. South of the windmill are the remains of
a bunkhouse, and a barn which also served as a garage. Further to the
east are corrals and holding pens for livestock.
The McDonalds vacated their ranch house and their thousands of acres
of marginal range land in early 1942 when it became part of the
Alamogordo Bombing and Gunnery Range. The old house remained empty
until Manhattan Project personnel arrived in 1945. Then a spacious
room in the northeast corner of the house was selected by the Project
personnel for the assembly of the plutonium core of the Trinity
device. Workmen installed work benches, tables, and other equipment
in this large room. To keep the desert dust and sand out, the room's
windows and cracks were covered with plastic and sealed with tape.
The core of the bomb consisted of two hemispheres of plutonium, (Pu-
239), and an initiator. According to reports, while scientists
assembled the initiator and the Pu-239 hemispheres, jeeps were
positioned outside with their engines running for a quick getaway if
needed. Detection devices were used to monitor radiation levels in
the room, and when fully assembled the core was warm to the touch.
The completed core was later transported the two miles to Ground Zero,
inserted into the bomb assembly, and raised to the top of the tower.
The Trinity explosion on Monday morning, July 16, did not
significantly damage the McDonald house. Even though most of the
windows were blown out, and the chimney was blown over, the main
structure survived intact. Years of rain water dripping through holes
in the metal roof did much more damage to the mud brick walls than the
bomb did. The nearby barn did not fare as well. The Trinity test
blew part of its roof off, and the roof has since totally collapsed.
The ranch house stood empty and deteriorating for 37 years until 1982
when the US Army stabilized it to prevent any further damage. The
next year, the Department of Energy and the Army provided funds for
the National Park Service to completely restore the house to the way
it appeared in July, 1945. When the work was completed, the house
with many photo displays on Trinity was opened to the public for the
first time in October 1984 during the semi-annual tour. The Schmidt-
McDonald ranch house is part of the Trinity National Historic
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