History’s 1st Atomic Bomb Exploded Here – And It’s Open Twice a Year for Tours

Trinity Site (New Mexico)

The Manhattan Project needed somewhere isolated to test their ultimate weapon. They chose a flat patch of New Mexico called Jornada del Muerto, the Journey of Death. At 5:29 AM on a summer morning, they split atoms and history in half.

Here’s the story of Trinity Site and how you can get on one of the rare tours today.

The Plutonium Gadget Design

Scientists built a bomb nicknamed ‘Gadget’ using plutonium for the Trinity test. It had the same design as the ‘Fat Man’ bomb later dropped on Nagasaki.

Gadget contained 13 pounds of plutonium, though only 3 pounds took part in the nuclear reaction. Engineers placed explosives around the plutonium core to squeeze it from all sides at the same time.

No one knew if this complex design would work, unlike the simpler uranium bomb used at Hiroshima.

The 100-Ton Test Rehearsal

Scientists ran a practice test on May 7, 1945. Workers stacked 108 tons of explosives on a 20-foot wooden platform 800 yards from the test area.

This trial let technicians adjust their measuring equipment and check timing systems. They mixed radioactive material with the explosives to track how dust would spread.

People saw the practice blast from 60 miles away. The data helped when preparing for the real test two months later.

The McDonald Ranch Assembly Point

Scientists put together the plutonium core in the master bedroom of McDonald Ranch House, just 2 miles from the test site.

Franz Schmidt built this adobe home in 1913 before the McDonald family bought it in the 1930s. Workers covered all windows with plastic and sealed doors with tape to keep dust out.

The team finished assembling the plutonium core on July 13, 1945, three days before the historic test.

Jumbo Containment Vessel

Project leaders worried the bomb might fail and scatter precious plutonium across the desert. They created ‘Jumbo,’ a massive steel container, to prevent this. Babcock & Wilcox in Ohio built this 214-ton steel cylinder for $12 million.

It stretched 25 feet long and 10 feet wide, with walls 14 inches thick. In the end, officials grew confident in the bomb design and decided not to use Jumbo.

Setting Up The 100-Foot Tower

Workers lifted the assembled Gadget to the top of a 100-foot steel tower. This height mimicked a bomb dropped from an airplane.

The team brought the plutonium core from McDonald Ranch and installed it into the bomb at the tower. During this process, the device nearly fell, causing panic. Technicians performed final checks on July 15, 1945, making everything ready for the next morning.

The Rain-Delayed Detonation

The team planned to detonate the bomb at 4:00 a.m. on July 16, 1945. Heavy rain and lightning forced them to wait.

At 4:45 a.m., weather forecasters delivered good news, allowing preparations to continue. The final 20-minute countdown began at 5:10 a.m. Scientists pressed the button at exactly 5:29:45 a.m., unleashing the first atomic bomb on the world.

The Blinding Explosion

Trinity released energy equal to 18.6 kilotons of TNT. Witnesses saw light brighter than several suns, lighting up mountains like daytime. The fireball instantly vaporized the steel tower.

Within seven minutes, a mushroom cloud climbed 38,000 feet into the sky. People saw the flash from 160 miles away. The explosion carved a half-mile crater and sent shock waves people felt 50 miles across the desert.

Scientists Who Witnessed History

The test deeply affected its creators. Oppenheimer later recalled thinking: ‘Now I am become Death, destroyer of worlds.’ Test director Bainbridge told Oppenheimer: ‘Now we are all sons of b*****s.’ General Leslie Groves and science advisor Vannevar Bush watched from a safe distance.

Physicist Richard Feynman claimed he watched without goggles, using only a truck windshield for protection. Enrico Fermi jokingly took bets on whether the blast might set the atmosphere on fire.

Creation Of Trinitite

The atomic blast generated temperatures of several million degrees. This heat fused desert sand into a green glass-like substance called ‘trinitite.’ The explosion formed a crater 4.7 feet deep and 88 yards wide.

Trinitite spread about 330 yards from the blast point. This material remains radioactive decades later. In 1952, government workers removed most trinitite and buried it, though small pieces remain at the site today.

Impact On Local Communities

Officials told locals the explosion came from an ammunition accident. They revealed the truth only after bombs fell on Japan. Nearly half a million people lived within 150 miles of Trinity Site, with some just 12 miles from ground zero.

No evacuation orders were given before or after the test. Today, ‘downwinders’ from nearby communities seek compensation for health problems they believe came from radiation exposure.

Visiting Trinity Site

Trinity Site opens to the public only on the first Saturday in April each year.

Visitors enter through Stallion Gate off Highway 380, between San Antonio and Carrizozo, New Mexico.

The site opens from 8:00 a.m. to 2:00 p.m. with no reservations required. Bring water, sunscreen, and wear closed-toe shoes. Photography is permitted, but no collecting of trinitite or other materials is allowed.

The tour includes Ground Zero, Jumbo, and the McDonald Ranch House. No admission fee is charged. For current information, call White Sands Missile Range Public Affairs Office or visit their website.