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Trinity Site - All You Need to Know BEFORE You Go (2024)

Trinity Site Offers a Rare Chance to Visit Ground Zero of the World’s First Atomic Bomb Explosion

The detonation site is only open to civilians twice a year

Jennifer Nalewicki

Travel Correspondent

July 16, 1945 was a day that changed the world forever. At 5:29 a.m. Mountain War Time, just minutes before sunrise, the night sky above central New Mexico was illuminated in a brilliant fireball of white light as the U.S. military tested the world’s first atomic bomb . Called Trinity Site and located on the grounds of the White Sands Missile Range about 70 miles west of Alamogordo, the site is typically off limits to civilians—but on October 7, visitors can experience it firsthand during its biannual open house.

Held on the first Saturday of every April and October, the open house is the only opportunity the public has to access the missile range, which normally serves as an active site for the U.S. Army to test out new weaponry. During the open house, visitors can see ground zero, where the plutonium-based A-bomb was detonated more than 70 years ago as part of the Manhattan Project . The open house also includes a visit to the McDonald Ranch House, a 1913 adobe home built by Frank Schmidt, a German immigrant, and where the device’s plutonium core was assembled.

Today, a monolith marks ground zero along with what’s left of the footing of a 100-foot tower that military personnel used during the detonation. Also on view: photos taken during the explosion, and the leftover bomb casing from “ Fat Man .”

“Most of the tower was vaporized during the explosion,” Drew Hamilton, a public information and community relations specialist for White Sands Missile Range, tells Smithsonian.com. “Since the explosion, much of the surrounding area has more or less returned to the way it would naturally be. There are no bushes growing around ground zero, but it’s because we regularly mow it. If we didn’t, it would look like the rest of the landscape.”

Visitors may also come across crumb-size pieces of Trinitite, a rock-like byproduct leftover from the explosion known for its glassy texture and deep green hue. (Since White Sands is a national monument, however, visitors are prohibited from removing anything from the site.)

And while Trinity Site has been cleaned up since the atom bomb detonation, its  radiation levels  remain above that of naturally occurring background levels. To put this into perspective, Hamilton gives the following example:

“Radiation is everywhere, it’s a naturally occurring phenomenon,” he says. “But it’s a little bit higher [at Trinity Site as compared to] the surrounding territory. During a one-hour visit, you’ll be exposed to approximately half a millirem of radiation. In comparison, during a flight aboard a commercial airliner from New York City to Los Angeles, you’ll be exposed to 2 millirems. You’ll get the same exposure from the Trinity Site as you would if you ate eight bananas, which, because of their potassium content, are naturally radioactive.”

This year’s Trinity Site open house will take place from 8 a.m. to 2 p.m. on October 7. Admission is free and reservations are not required. Pets are allowed and must be leashed. To reach Trinity Site, take exit 139 off Interstate 25 to State Highway 380 and drive east 12 miles to Stallion Gate. Make sure to bring a valid ID to show at security checkpoints. Drivers should be prepared to provide proof of insurance. 

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Jennifer Nalewicki | | READ MORE

Jennifer Nalewicki is a Brooklyn-based journalist. Her articles have been published in The New York Times , Scientific American , Popular Mechanics , United Hemispheres and more. You can find more of her work at her website .

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Trinity site.

www.wsmr.army.mil/Trinity

The world was forever changed on July 16 th, 1945 at the Trinity Test Site. It was here at the White Sands Missile Range that the first atomic bomb was detonated and brought a quick end to the Second World War in the Pacific. Today it is a national historical site that is open to visitors just 2 days per year, (pending Army approval) in April and October.  Visitors can see ground zero, the ranch house where the bomb was assembled, and one of the instruments bunkers. For more information about visiting the site go to www.wsmr.army.mil/Trinity

History of Trinity Site www.nps.gov/whsa/learn/historyculture/trinity-site.html

You have a few different options when it comes to visiting Trinity Site.  You can enter through the Stallion Gate which is off of Hwy 380 between Carrizozo and San Antonio, NM at the times specified on the White Sands Missile Range website.  You can also caravan into the site, this route takes you from Tularosa, NM through the Missile Range with other travelers. To participate in the caravan you need to meet in the Athletics parking lot on the west side of the Tularosa High School off of La Luz Ave.  Line up starts at 7 am and the caravan will leave promptly at 8 am.  Please arrive no later than 7:45 am so that officers will have a chance to check your license and registration, and give you a pass to place in your window signifying that you are a part of the caravan.  You may return to Tularosa with the caravan between 12:30 and 1 pm, or leave on your own through the Stallion Gate.  Please ensure that you have a full tank of gas and bring plenty of water with you.  Finally, the International Space Hall of Fame Foundation (New Mexico Museum of Space History support group) hosts a guided tour to the site in charter buses, they also provide b a sack lunch, water, and a guide tour of the museum upon return.

Find more info and register for the guided tour at http://nmspacetrail.com/sites/NMMSH/Trinity-Site-Tour/register.html For more information about the caravan lineup https://www.alamogordo.com/trinity-site / New weekend itinerary coming soon!

NEW!!! The Tularosa Basin Museum of History is hosting a viewing followed by a Q&A, of the new documentary, 'Alamogordo, Center of the World, Trinity 1945' the Friday evening before each open house.  Tickets are available through the museum at the corner of White Sands Blvd & 10th, 575-434-4438.  The film will be shown at the historic Flickinger Center for Performing Arts (1110 New York Ave. Alamogordo, NM) in downtown Alamogordo. For more info call 575-437-2202.

Directions to Trinity Site: http://www.wsmr.army.mil/Trinity/Pages/DirectionsMaps.aspx

More information about the caravan to Trinity Site visit www.alamogordo.com

Map to caravan lineup site, limited to 125 vehicles.

White Sands Missile Range Museum

Atomic. Missile. Space. Birthplace of American Ages.

Trinity Site

About Trinity Site

The story of Trinity Site begins with the formation of the Manhattan Project in June 1942. The project was given overall responsibility for designing and building an atomic bomb. At the time, it was a race to beat the Germans who, according to intelligence reports, were building their own atomic bomb.

Under the Manhattan Project, three large facilities were constructed. At Oak Ridge, Tennessee, huge gas diffusion and electromagnetic process plants were built to separate uranium-235 from its more common form, uranium-238. Hanford, Washington became the home for nuclear reactors which produced a new element called plutonium-239. Both uranium-235 and plutonium-239 are fissionable and can be used to produce an atomic explosion.

Los Alamos was established in northern New Mexico to design and build the bomb. At Los Alamos, many of the greatest scientific minds of the day labored over the theory and actual construction of the device. The group was led by Dr. J. Robert Oppenheimer, who is credited with being the driving force behind building a workable bomb by the end of the war.

Los Alamos scientists devised two designs for an atomic bomb, one using uranium-235 and another using plutonium-239. The uranium bomb was a simple design and scientists were confident it would work without testing. The plutonium bomb was more complex and worked by compressing the plutonium into a critical mass which sustains a chain reaction. The compression of the plutonium ball was to be accomplished by surrounding it with lens-shaped charges of conventional explosives. They were designed to all explode at the same instant. The force is directed inward, thus smashing the plutonium from all sides.

In an atomic explosion, a chain reaction picks up speed as atoms split, releasing neutrons plus great amounts of energy. The escaping neutrons strike and split more atoms, thus releasing still more neutrons and energy. In a nuclear explosion, this all occurs in a millionth of a second with billions of atoms being split.

Project leaders decided a test of the plutonium bomb was essential before it could be used as a weapon of war. From a list of eight sites in California, Texas, New Mexico, and Colorado, Trinity Site was chosen as the test site. The area already was controlled by the government because it was part of the Alamogordo Bombing and Gunnery Range, which was established in 1942. The secluded Jornada del Muerto was perfect as it provided isolation for secrecy and safety, but was still close to Los Alamos.

Beginnings of Trinity Site

In the fall of 1944, soldiers starting arriving at Trinity Site to prepare for the test. Marvin Davis and his military police unit arrived from Los Alamos at the site on 30 December 1944. The unit set up security checkpoints around the area and had plans to use horses to ride patrol. According to Davis, the distances were too great and they resorted to jeeps and trucks for transportation. The horses were sometimes used for polo, however. Davis said that Captain Bush, Base Camp Commander, somehow got the soldiers real polo equipment to play with, but they preferred brooms and a soccer ball.

Other recreation at the site included volleyball and hunting. Davis said Captain Bush allowed the soldiers with experience to use the Army rifles to hunt deer and pronghorn. The meat was then cooked up in the mess hall. Leftovers went into soups which Davis said were excellent.

Of course, some of the soldiers were from cities and unfamiliar with being outdoors in the American southwest. Davis said he went to relieve a guard at the Mockingbird Gap post and the soldier told Davis he was surprised by the number of “crawdads” in the area considering it was so dry. Davis gave the young man a quick lesson on scorpions and warned him not to touch.

Throughout 1945, other personnel arrived at Trinity Site to help prepare for the test. Carl Rudder was inducted into the Army on 26 January 1945. He said he passed through four camps, attended basic for two days, and arrived at Trinity Site on 17 February. On arriving, he was put in charge of what he called the “East Jesus and Socorro Light and Water Company.” It was a one-man operation, himself. He was responsible for maintaining generators, wells, pumps, and doing the power line work.

A friend of Rudde, Loren Bourg, had a similar experience. He was a fireman in civilian life and ended up trained as a fireman for the Army. He worked as the station sergeant at Los Alamos before being sent to Trinity Site in April 1945. In a letter, Bourg said, “I was sent down here to take over the fire prevention and fire department. Upon arrival I found I was the fire department, period.”

As the soldiers at Trinity Site settled in, they became familiar with Socorro. They tried to use the water out of the ranch wells but found it so alkaline they couldn’t drink it. In fact, they used Navy salt-water soap for bathing. They hauled drinking water from the fire house in Socorro. Gasoline and diesel was purchased from the Standard bulk plant in Socorro.

According to Davis, they established a post office box, number 632, in Socorro so getting their mail was convenient. All the trips into town also offered them the chance to get their hair cut in the barbershop in town. If they didn’t use the shop, Sergeant Greyshock used horse clippers to trim their hair.

The bomb design to be used at Trinity Site actually involved two explosions. First, there would be a conventional explosion involving the TNT and then, a fraction of a second later, the nuclear explosion, as long as a chain reaction was maintained. The scientists were sure the TNT would explode, but were initially unsure of the plutonium core. If the chain reaction failed to occur, the TNT would blow the very rare and dangerous plutonium all over the countryside.

Because of this possibility, Jumbo was designed and built in Ohio. Originally, it was 25 feet long, 10 feet in diameter, and weighed 214 tons. Scientists were planning to put the bomb in this huge steel jug because it could contain the TNT explosion if the chain reaction failed to materialize. This would prevent the plutonium from being lost. If the explosion occurred as planned, Jumbo would be vaporized.

Jumbo was brought to Pope, New Mexico, by rail and unloaded. A specially-built trailer with 64 wheels was used to move Jumbo the 25 miles to Trinity Site.

As confidence in the plutonium bomb design grew, it was decided not to use Jumbo. Instead, it was placed under a steel tower about 800 yards from Ground Zero. The blast destroyed the tower, but Jumbo survived intact.

Today it rests at the entrance to ground zero so all can see it. The ends are missing because, in 1946, the Army placed eight 500-pound bombs inside it and detonated them.

Preparing the Gadget

To calibrate the instruments which would be measuring the atomic explosion and to practice a countdown, the Manhattan Project scientists ran a simulated blast on 7 May. They stacked 100 tons of TNT onto a 20-foot wooden platform just southeast of Ground Zero. Louis Hempelmann inserted a small amount of radioactive material from the Hanford, Washington facility into tubes running through the stack of crates. The scientists hoped to get a feel for how the radiation might spread in the real test by analyzing this test. The explosion destroyed the platform, leaving a small crater with trace amounts of radiation in it.

On 12 July, the two hemispheres of plutonium were carried to the George McDonald Ranch House just two miles from Ground Zero. At the house, Brigadier General Thomas Farrell, deputy to Major General Leslie Groves, was asked to sign a receipt for the plutonium. Farrell later said, “I recall that I asked them if I was going to sign for it shouldn’t I take it and handle it. So I took this heavy ball in my hand and I felt it growing warm, I got a certain sense of its hidden power. It wasn’t a cold piece of metal, but it was really a piece of metal that seemed to be working inside. Then maybe for the first time I began to believe some of the fantastic tales the scientists had told about this nuclear power.”

At the McDonald Ranch House, the master bedroom had been turned into a clean room for the assembly of the bomb core. According to Robert Bacher, a member of the assembly team, they tried to use only tools and materials from a special kit. Several of these kits existed and some were already on their way to Tinian by different routes. The idea was to test the procedures and tools at Trinity in addition to the bomb itself.

At one minute past midnight on Friday, 13 July, the explosives assembly left Los Alamos for Trinity Site. Later in the morning, assembly of the plutonium core began. According to Raemer Schreiber, Robert Bacher was the advisor, Marshall Holloway and Philip Morrison had overall responsibility. Louis Slotin, Boyce McDaniel, and Cyril Smith were responsible for the mechanical assembly in the ranch house. Later, Holloway was responsible for the mechanical assembly at the tower.

In the afternoon of the 13 th , the core was taken to Ground Zero for insertion into the bomb mechanism. The bomb was assembled under the tower on 13 July. The plutonium core was inserted into the device with some difficulty. On the first try it stuck. After letting the temperatures of the plutonium and casing equalize, the core slid smoothly into place. Once the assembly was complete, many of the men went swimming in the water tank east of the McDonald Ranch House.

The next morning, the entire bomb was raised to the top of the 100-foot steel tower and placed in a small shelter. A crew then attached all the detonators and the Gadget was complete by 5:00pm.

Observation Points

Three observation points were established at 10,000 yards from Ground Zero. These were wooden shelters protected by concrete and earth. The south bunker served as the control center for the test. The automatic firing device was triggered from there as key men such as Dr. Robert Oppenheimer, head of Los Alamos, watched. None of the manned bunkers are left.

Many scientists and support personnel, including Major General Leslie Groves, head of the Manhattan Project, watched the explosion from Base Camp, which was ten miles southwest of Ground Zero. All the buildings at Base Camp were removed after the test. Most visiting VIPs watched from Compania Hill, 20 miles northwest of Ground Zero.

The Day of the Trinity Test

The test was scheduled for 4:00am on 16 July, but rain and lightning early that morning caused it to be postponed. The device could not be exploded under rainy conditions because rain and winds would increase the danger from radioactive fallout and interfere with observation of the test. At 4:45am, the crucial weather report came through announcing calm to light winds with broken clouds for the following two hours.

At 5:10am, the countdown started. At 5:29:45am, the Gadget exploded successfully. To most observers, the brilliance of the light from the explosion, watched through dark glasses, overshadowed the shock and sound wave that arrived later.

Hans Bethe, one of the contributing scientists, wrote that “it looked like a giant magnesium flare which kept on for what seemed a whole minute but was actually one or two seconds. The white ball grew and after a few seconds became clouded with dust whipped up by the explosion from the ground and rose and left behind a black trail of dust particles.”

Joe McKibben, another scientist, said, “We had a lot of flood lights on for taking movies of the control panel. When the bomb went off, the lights were drowned out by the big light coming in through the open door in the back.”

Others were impressed by the heat they immediately felt. Military policeman Davis said, “The heat was like opening up an oven door, even at 10 miles.” Dr. Phillip Morrison said, “Suddenly, not only was there a bright light but where we were, 10 miles away, there was the heat of the sun on our faces… Then, only minutes later, the real sun rose and again you felt the same heat to the face from the sunrise. So we saw two sunrises.”

Although no information on the test was released until after the atomic bomb was used as a weapon against Japan, people in New Mexico knew something had happened. The shock broke windows 120 miles away and was felt by many at least 160 miles away. Army officials simply stated that a munitions storage area had accidentally exploded at the Alamogordo Bombing Range.

The explosion did not make much of a crater. Most eyewitnesses describe the area as more of a small depression. The heat of the blast vaporized the steel tower and melted the desert sand and turned it into a green glassy substance. It was called Trinitite and can still be seen in the area. At one time, Trinitite completely covered the depression made by the explosion. Afterwards, the depression was filled in and much of the Trinitite was taken away by the Nuclear Energy Commission.

The story of what happened at Trinity Site did not come to light until after the second atomic bomb was exploded over Hiroshima, Japan on 6 August 1945. President Truman made the announcement that day. Three days later, 9 August, the third atomic bomb devastated the city of Nagasaki, and on 14 August, the Japanese surrendered.

Trinity Site became part of what was then White Sands Proving Ground. The Proving Ground was established on 9 July 1945 as a test facility to investigate the new rocket technology emerging from World War II. The land, including Trinity Site and the old Alamogordo Bombing Range, came under the control of the new rocket and missile testing facility.

In September 1945, press tours to the site started. One of the famous photos of Ground Zero shows Groves and Oppenheimer surrounded by a small group of reporters as they examine one of the footings to the 100-foot tower on which the bomb was placed. That picture was taken 11 September. At first, Trinity Site was encircled with a fence and radiation warning signs were posted. The site remained off limits to military and civilian personnel of the Proving Ground and closed to the public.

In 1952, the Atomic Energy Commission led a contract to clean up the site. Much of the Trinitite was scraped up and buried. In September 1953, about 650 people attended the first Trinity Site Open House. A few years later, a small group from Tularosa visited the site on the anniversary of the explosion to conduct a religious service and prayer for peace. In 1967, the inner oblong fence was added. In 1972, the corridor barbed wire fence which connects the outer fence to the inner one was completed. Jumbo was moved to the parking lot in 1979.

UponArriving

Trinity Site Open House Guide (New Mexico)

Over the years of turning out content for this blog, I’ve visited a lot of historical sites but I’ve never visited a site quite like the Trinity Site in New Mexico.

It’s an ultra-remote site barely ever open to the public and it’s home to one of the most pivotal moments in mankind’s history.

If you have any type of interest in the atomic era, this is a bucket-list worthy destination for sure.

In this article, I’ll tell you everything you need to know about visiting the Trinity Site’s open house.

Table of Contents

What is the Trinity Site?

The Trinity Site is where the first nuclear bomb exploded on July 16, 1945 at 5:29 AM mountain war time. Two days out of the year there is an open house that allows the public to visit the site along with other related sites like the McDonald Ranch House.

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How to visit the Trinity Site

It is free to visit the Trinity Site but you can only visit the site two days out of the yea r, which is usually the first Saturday of April and October. However, sometimes they do change the dates around a little bit.

There are three main ways that you can visit the Trinity Site.

Alamogordo Caravan

One way to experience the Trinity Site is to take part in the Alamogordo Caravan.

Line up for the caravan begins at 7:00am at the Tularosa High School Athletic Field parking lot and the tour will enter the missile range through the Tularosa Gate at 8:00am and arrive at Trinity Site around 10am.

It is only open to the first 125 vehicles that show up. 

The journey is 85 miles one-way to Trinity Site.

Stallion Gate

The other way to experience the Trinity Site (which is the way that we did it) is to simply arrive at the Stallion Gate. This gate is located on the north side of the missile range on U.S. highway 380, 12 miles east of San Antonio, NM.

The Stallion Gate Hours are from 8:00 a.m. to 2:00 p.m. and the Trinity Site closes promptly at 3:30 p.m

Once you show up at the military testing site, you’re not allowed to take any photos until you arrive inside the Trinity site so keep that in mind.

It’s about a 30 minute drive from the Stallion Gate to the parking lot for the Trinity Site.

At the Stallion Gate, you’ll go through a security checkpoint where every passenger 18 years and older will need to show an ID and declare that they are not bringing in weapons or any illegal items. (It only takes a few seconds to get through.)

Once you arrive at the parking area, military personnel will direct you to your specific parking spot.

Related: New Mexico Safety Corridors Explained 

Book a tour

You can also book a tour to get you there.

For example, the New Mexico Museum of Space History offers a package deal where you can get a bus ride to and from the site, some snacks, and access to the museum.

We checked out the museum and thought that it was a pretty well done space museum. They also have a small exhibit on Trinitite which was cool to see.

Where to stay

You might consider staying in Albuquerque, New Mexico, or in Alamogordo which is where we stayed because we decided to explore the New Mexico Museum of Space History and White Sands National Park the next day.

If you’re headed to Albuquerque, be sure to check out The National Museum of Nuclear Science & History and consider adding Los Alamos as an additional stop.

Los Alamos was the headquarters for the Manhattan Project and they still have a couple of museums you can check out like the  Los Alamos History Museum  and the Bradbury Science Museum .

Trinity Site history

To fully grasp and appreciate the history of the Trinity Site it helps to understand how it fits into the overall efforts of creating the atomic bomb.

The history of the atomic bomb begins in Berlin, Germany when in 1938, scientists discovered how to split the nucleus of the uranium atom (fission).

This discovery came close to the beginning of World War II when Adolf Hitler invaded Poland in September 1939.

The breakthrough in fission created serious worry that the Nazis would get their hands on a nuclear weapon which would obviously not be ideal to say the least.

Concerned Hungarian physicists helped write a letter to President Roosevelt (FDR), signed by none other than Albert Einstein, to warn the US about the prospect of an “extremely powerful” Nazi atomic bomb.

After that, it didn’t take long for FDR to authorize a top-secret project to begin researching the atomic bomb.

The initiative went through a few name changes but ended up as the: Office of Scientific Research and Development (OSRD).

Things took off after the bombing of Pearl Harbor on December 7, 1941 when the US found itself involved in World War II with a formal declaration of war on both Japan and Germany.

President Roosevelt authorized the Manhattan Project on December 28, 1942 and on the 18th floor of 270 Broadway in New York City, the Manhattan Project began.

General Leslie Groves was appointed to lead the Manhattan Project after just just finishing the completion of the Pentagon.

Groves went on to recruit Robert Oppenheimer, an instructor at the University of California at Berkeley and a bit of an odd selection given his lack of managerial experience and associations to communism via family members.

But he proved to be an ideal candidate and an excellent recruiter of scientific talent.

The Manhattan project sought to create atomic bombs from two substances: uranium and plutonium.

For uranium, they were focused on acquiring U-235 and they built a huge complex and town in Oak Ridge, Tennessee to accommodate 30,000 workers .

For Plutonium, the Hanford Engineer Works produced plutonium at a site along the Columbia River in Washington state.

They also needed a place to develop and test the bombs.

They wanted somewhere secret and remote but still appealing enough to attract renowned scientists all over the world so they went with Los Alamos, New Mexico.

On January 1, 1943, the Los Alamos Laboratory — known as Project Y — was formally established .

And a few months later , the University of California signed a contract with the United States Army Corps of Engineers to operate the secret laboratory.

They once again built an entire city just for the purpose of the Manhattan Project and hundreds of people would arrive to the city with no clear idea as to what they were actually building.

(Pretty much only scientific personnel had an idea of what they were doing.)

Questions were highly discouraged and on paper the city didn’t actually exist.

Many experiments were done as the teams collaborated to construct the bombs and waiting for the nuclear material to arrive. At some point, though, it became clear that the plutonium bomb was going to be an issue.

The issue was that creating an explosion with plutonium was a much more complicated process.

The scientist had to create an entirely different type of mechanism to initiate the chain reaction and that’s when they came up with implosion.

The implosion-type nuclear weapon , “held a core of subcritical plutonium which would reach criticality when high explosives surrounding the core detonated causing the core to compress instantly.”

The creation of this new type of work and was so challenging that it required bringing in a lot more scientists. Unfortunately, when bringing in more talent at least one Russian spy made his way into the team.

The team would ultimately make progress but unexpected challenges arose in April 1945 and the work was interrupted when FDR died in office.

Shockingly, the Vice President Harry Truman did not even know about the Manhattan Project when he took office!

A month later, on May 7, 1945, Germany would surrender but the war was still going strong in the Pacific Theater and an atomic weapon was being considered for use against the Empire of Japan.

The allies had battered the Empire of Japan’s military down to a shadow of what it had been before but casualties were still running very high.

But before any bombs would be dropped, some testing needed to be done.

Testing at the Trinity Site

Back in September 1944, around the time nuclear material was arriving, New Mexico’s Alamogordo Bombing and Gunnery Range (aka the Trinity Site) had been selected as the the test location .

It was located about 210 miles south of Los Alamos, and in November 1944 construction of the base camp began.

All of the components of the uranium atomic bomb had been tested giving scientists the mathematical certainty they needed to know that the bomb would work.

But because the plutonium bomb was more complex they needed a test run to ensure that it would work.

The plutonium bomb set to be tested at the Trinity Site was known as “Gadget.”

The core of the bomb consisted of a grapefruit-sized ball of plutonium and was delivered to the McDonald Ranch House on July 11, 1945 and the bomb was assembled on July 13, 1945.

The bomb, a large 6-foot sphere covered with wires and patched up with tape, was then hoisted up a 100-foot steel tower for the test.

At the time, none of the scientists truly knew what was going to happen. In fact, many thought the bomb would be a dud.

On the day of the test, the weather did not cooperate at first and the team postponed the test until the skies cleared up a little bit.

Then at 5:29:45 a.m. Mountain War Time on July 16, 1945, first atomic bomb was tested .

After the bomb exploded, clouds of bright reds and purples filled the sky up to 40,000 feet high. People said they felt the warmth of the sun.

Local newspapers were told that an ammunition depot had exploded which had resulted in the spectacular display but those at the site knew the truth: humankind had entered the atomic age.

The Trinity site

Ground zero.

Ground Zero is about a quarter mile away from the parking lot so you have to walk a little bit to get there.

Once you arrive, you’ll see a monument towering in the middle.

Erected in 1965, The Trinity Monument is a lava-rock obelisk about 12 feet (3.7 m) high that marks the explosion’s hypocenter.

Crowds gather around the monument pretty quickly so you might need to exercise some patience to get a photo.

Right next to the obelisk, you can find the remains of the 100 foot steel tower that hoisted Gadget.

Along the perimeter of Ground Zero, you’ll find photos hanging from the fence that will give you some insight into everything going on at the time of the test. It’s best to start from right to left when viewing these.

There’s a structure that covers some of the original soil from the test but sand and dust got in and covered up the original soil so the viewing window has been closed.

There’s also a bomb casing that I believe was going to be used for future atomic bombs. It’s almost identical to the casing used for the fat man bomb which was dropped on Nagasaki.

Trinitite is a radioactive green glass-like substance that covered the depressed area where the explosion took place after the test.

There’s different explanations as to how the trinitite was formed.

The simple and long-held explanation is that the heat simply heated the sand until it became glass.

One hypothesis is that the explosion brought pieces of sand and rock into the fireball and liquefied the pieces which eventually fell down like rain into the crater and hardened.

I’m not sure which explanation might be more accurate but I think it’s safe to say that it had a lot to do with the heat from the explosion.

Most of the trinity it is light green but other pieces are slightly different colors. Some are black and others look slightly red and that’s because those contain elements that were vaporized during the test.

For example, the black pieces contain elements from the steel tower and the red pieces contain elements from the copper in the wires.

If you stroll around Ground Zero and look closely at the ground it won’t be very difficult to find pieces of trinitite.

They possess background levels of radiation and you are okay to touch them but probably not a good idea to do something stupid with them like swallow them. It’s also a federal crime to remove them from the property.

You’ll also want to stop by the trinitite fueling station. Here, you can get a close look at trinitite and also use a geiger counter to detect the radiation levels of the trinitite.

McDonald Ranch House

The McDonald Ranch House is where they assembled the bomb on July 13, 1945. Built in 1913 by Franz Schmidt, a German immigrant and acquired by the McDonald family in the 1930s, the ranch was eventually taken over by the government in 1942.

In order to get there, you need to head to the bus stop which is located right by the parking lot. It’s only about a 5 to 10 minute bus ride to get to the ranch house. Keep in mind that dogs are not allowed on the bus unless they are service animals.

When you arrive, you can simply wander through the McDonald Ranch House at your own pace. There should be somebody inside that can help answer any questions you might have and who can show you around.

They also had a table with photographs set out in front so you can learn a little bit more about the structure.

The northeast room was designated the assembly room where they had work benches and tables.

To keep all of the sand and dust from ruining the instruments, they covered the windows and walls with plastic. In fact, you can still see some of the nails that were used to seal up the windows.

As mentioned above, the plutonium core was delivered to the ranch house on July 11, 1945 and it was assembled on July 13, 1945.

The explosion occurred only 2 miles (3.2 km) away and it blew most of the home’s windows out but did not significantly damage the structure.

Instead, it was the years of rain water leaking through the roof that was responsible for the deterioration.

In 1984 it was restored by the National Park Service to appear as it did on July 12, 1945

Near the main parking lot you’ll see Jumbo which is a large structure which was once the heaviest object to ever be transported by rail.

The 25-foot jumbo container was initially going to be used to contain the plutonium with its 14 inch thick walls in the event of a botched explosion.

However, after they realized that they would have plenty of plutonium for additional bombs they didn’t need to use jumbo for the explosion.

So they hoisted it from a tower about 800 yards away from ground zero and while that tower would be vaporized during the explosion, jumbo would remain intact.

While they did not use it for this explosion, it was used on April 16, 1946, when an Army ordnance team detonated eight 500 lb bombs in the bottom of the steel container.

Food and souvenirs

You’ll also be able to find food and souvenirs at the Trinity site.

Souvenirs range from about $3 to $20 and they have a lot of the typical stuff like magnets, stickers, patches, and T-shirts.

As for food, they’ll have breakfast burritos, hamburgers, hotdogs, and some other snacks. I believe the registers should take credit cards but I would bring cash just in case.

Also, they do have bathrooms which are a little bit of a walk from the parking lot.

Visiting the Trinity Site is not very easy because it is only open two days out of the year and it’s basically in the middle of nowhere.

But it is still absolutely worth planning out a visit because it’s hard to find a location that compares to the Trinity Site in terms of its importance to the history of mankind.

Daniel Gillaspia is the Founder of UponArriving.com and the credit card app, WalletFlo . He is a former attorney turned travel expert covering destinations along with TSA, airline, and hotel policies. Since 2014, his content has been featured in publications such as National Geographic, Smithsonian Magazine, and CNBC. Read my bio .

very informative. i am planning a visit in october 2023. was wondering about the mcdonald ranch house, and you answered all my questions…. this trip in october will knock off another event on my bucket list.

July 2023: The tour package is now $150 per person.

Confused. Sorry. From a that I see it’s free to drive and take pictures of the monument and see site from distance What is the 150.00 Charge for. It’s free to drive up and see site frown distance Can I also see McDonald house for free. Please advise. Coming from Dallas How can I get free brochures for trinity mailed to me on trinity testing Came I get a number to call. Please let me know.

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Guided Tour to Trinity Site 2021

October 1, 2021 @ 3:34PM — October 2, 2021 @ 3:34PM Eastern Time (US & Canada)

Trinity Site is open only twice a year, and we will take you there!

There are currently no tickets available for this event, but you can still make a donation.

Trinity Site, the location where on July 16, 1945, the first man-made nuclear explosion was detonated, is open only twice a year, and the Los Alamos Historical Society is offering a guided tour to the site October 1-2 for the fall opening.

The Society's Trinity Tour includes a two-day, one night experience via the Alamogordo southern approach through the seldom-seen interior of White Sands Missile Range. Departure from Trinity Site will be out of the northern Stallion Gate, with a lunch stop at New Mexico Tech in Socorro.

Bonuses include a visit to the young (5,000-year-old) lava flows of Valley of Fires, and the New Mexico Space Museum overlooking the Tularosa Basin, Holloman Air Force Base, and White Sands Missile Range. This excursion aboard a comfortable, restroom-equipped coach includes experienced tour direction with Georgia and Gerry Strickfaden, leading their eighteenth trip to Trinity.

The cost for Historical Society members is $400/person double occupancy and $500 for non-members, with an $80 single supplement for either. The price includes a tax-deductible donation to the Los Alamos Historical Society.

What's included: Overnight parking at Holiday Inn Express in Los Alamos, a seat on a luxury tour bus, hotel room, all meals excluding Friday night dinner, admission fees, tour guide.

Only 38 seats are available, so don't delay reserving yours.

If you'd prefer to pay by check, please email [email protected]

Refunds, minus a $50 processing fee, can be made through September 15.

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Manhattan Project National Historical Park c/o NPS Intermountain Regional Office P.O. Box 25287 Denver, CO 80225-0287

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Trinity Site - All You Need to Know BEFORE You Go (2024)

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Visitors tour New Mexico atomic site in likely record attendance fueled by ‘Oppenheimer’ fanfare

FILE - Scientists and other workers rig the world’s first atomic bomb to raise it up onto a 100-foot tower at the Trinity Test Site near Alamogordo, N.M. The New Mexico site where the world’s first atomic bomb was detonated is expecting thousands of visitors Saturday due to the popularity of the movie, “Oppenheimer.” Trinity Site, a designated National Historic Landmark, only opens to the public twice a year. (AP Photo/File )

FILE - This photo shows an aerial view after the first atomic explosion at the Trinity Test Site near Alamogordo, N.M., on July 16, 1945. The New Mexico site where the world’s first atomic bomb was detonated is expecting thousands of visitors Saturday due to the popularity of the movie, “Oppenheimer.” Trinity Site, a designated National Historic Landmark, only opens to the public twice a year. (AP Photo, File)

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WHITE SANDS MISSILE RANGE, N.M. (AP) — Visitors lined up Saturday to tour the southern New Mexico site where the world’s first atomic bomb was detonated in what officials believe could be a record turnout amid ongoing fanfare surrounding Christopher Nolan’s blockbuster film, “ Oppenheimer .”

Thousands of visitors are expected at the Trinity Site, a designated National Historic Landmark that’s usually closed to the public because of its proximity to the impact zone for missiles fired at White Sands Missile Range. But twice a year, in April and October, the site opens to spectators. No attendance numbers were immediately available at midnight Saturday. In a social media post, the missile range said vehicles were lined up for more than 2 miles at the site before the tours started Saturday.

White Sands officials warned online that the wait to enter the gates could be as long as two hours. No more than 5,000 visitors are expected to make it within the window between 8 a.m. and 2 p.m.

Visitors also are being warned to come prepared as Trinity Site is in a remote area with limited Wi-Fi and no cell service or restrooms.

“Oppenheimer,” the retelling of the work of J. Robert Oppenheimer and the top-secret Manhattan Project during World War II, was a summer box office smash. Scientists and military officials established a secret city in Los Alamos during the 1940s and tested their work at the Trinity Site some 200 miles (322 kilometers) away.

Part of the film’s success was due to the “Barbenheimer” phenomenon in which filmgoers made a double feature outing of the “Barbie” movie and “Oppenheimer.”

While the lore surrounding the atomic bomb has become pop culture fodder, it was part of a painful reality for residents who lived downwind of Trinity Site . The Tularosa Basin Downwinders plan to protest outside the gates to remind visitors about a side of history they say the movie failed to acknowledge.

The group says the U.S. government never warned residents about the testing. Radioactive ash contaminated soil and water. Rates of infant mortality, cancer and other illnesses increased. There are younger generations dealing with health issues now, advocates say.

The Tularosa Basin Downwinders Consortium has worked with the Union of Concerned Scientists and others for years to bring attention to the Manhattan Project’s impact. A new documentary by filmmaker Lois Lipman, “First We Bombed New Mexico,” made its world premiere Friday at the Santa Fe International Film Festival.

The notoriety from “Oppenheimer” has been embraced in Los Alamos, more than 200 miles (321 kilometers) north of the Tularosa Basin. About 200 locals, many of them Los Alamos National Laboratory employees, were extras in the film, and the city hosted an Oppenheimer Festival in July.

Trinity Site: What you need to know before you go

WHITE SANDS MISSILE RANGE — At precisely 5:29:45 a.m. on July 16, 1945, a tremendous explosion in the New Mexico desert signaled the beginning of the end of World War II.

The explosion was the world's first atomic bomb and as part of the Manhattan Project, it had been tested at the Trinity Site, now known as the north end of White Sands Missile Range.

Today Trinity Site is open to the public at 8 a.m. but closes promptly at 3:30 p.m.

According to White Sands Missile Range, the atomic bomb released 19 kilotons of power, instantly vaporizing the tower it was on and turning the surrounding asphalt and sand into green glass. The shock of the bomb broke windows 120 miles away and was felt by many as far away as 160 miles.

Success of the test meant an atomic bomb using plutonium could be used by the United States military in Japan during World War II.

Tour the Trinity Site

Touring the Trinity Site is free but it's only opened to the public twice a year, on the first Saturday in April and October. Thousands of visitors enter the site from either the Stallion Range Gate or the Tularosa Gate.

Entering the site from the Tularosa Gate entails joining your vehicle in a caravan at Tularosa High School football field parking lot, 1305 Eight St., in Tularosa. This caravan enters the site at 8 a.m. and is led by military police. From the Tularosa Gate, it's a 75-mile drive to the site and there are no gas stations on the route or at the site.

Everyone 18 and older must show a valid driver's license , pass port or DoD issued identification. All vehicles are subject to search and should be carrying proof of insurance and current registration papers. No weapons of any kind are allowed on the installation.

Entering the site from the Stallion Range Gate is a 17-mile trip and visitors are allowed to drive in and out of the site unescorted from 8 a.m. to 2 p.m. The Stallion Range Gate is located five miles south of U.S. Highway 380 and the turnoff is 12 miles east of San Antonio and 53 miles west of Carrizozo. 

Both roads are paved and marked. The site closes promptly at 3:30 p.m.

At the site, visitors can take a quarter-mile walk to ground zero where a small obelisk marks the exact spot where the bomb was exploded. Historical photos are mounted on the fence surrounding the area. Visitors also can ride a missile range shuttle bus two miles to the Schmidt/McDonald ranch house. The ranch house is where the scientists assembled the plutonium core of the bomb.

Tularosa Basin Downwinders

The Tularosa Basin Downwinders believe the Trinity test disturbed the genetics of residents in surrounding communities, leaving a cluster of cancer and illness in the those who witnessed the atomic bomb, and their descendants. For 13 years, the Downwinders have collected data, met with New Mexico's U.S. senators and continued fighting for inclusion in the Radiation Exposure Compensation Act (RECA).

Semiannually when the Trinity Site opens to the public, the Downwinders host peaceful demonstrations at the Stallion Range and Tularosa Gates, informing visitors about their cause. 

More: Downwinders aim to educate public about Trinity Site test

The Downwinders have been invited twice to testify in front of Congress during hearings for RECA amendments but both times the hearings have been postponed. The Downwinders were recently given word that the hearings might be rescheduled for this summer and are preparing to travel to Washington, D.C. 

Last month, the Downwinders hosted a town hall in Carrizozo and listened to residents who were just 33 miles from the Trinity Site when the atomic bomb was tested. 

Read More: Tularosa Basin Downwinders to host Carrizozo town hall

Read More: Tularosa Downwinders make strides in battle for recognition

For more information about the Tularosa Basin Downwinders, visit their website at  www.trinitydownwinders.com . 

For more information about Trinity Site go online at wsmr.army.mil/Trinity/Pages/Home.aspx