Monday, July 16, 2007


The following story is from 1945, and is true:

Marty had been excited when she boarded the bus that would take her from Jacksonville, Illinois, to Tucson, Arizona. The war in Europe was over, which meant Bud would be returning home. Marty didn't know just when Bud would get home. But she wanted to get back to Tucson, eager to be home again and eager to lay the groundwork so she and Bud could get married as soon as possible after he returned.

Now it was late at night (actually, early in the morning) as the bus rolled across New Mexico. Everyone else was asleep — only Marty and the bus driver were awake, and they were in the middle of a long discussion. Suddenly, the sky lit up with a brilliant light that seemed brighter than mid-day. Everything in sight stood out, but it wasn't obvious where the light was coming from.

The discussion stopped. When it started again, the topic for all the rest of the trip to Tucson was “What was that????” Marty and the bus driver were unable to find any reasonable explanation.

Marty figured it out three weeks later when the newspaper headlines told of the use of a new type of weapon — an atomic bomb — over Hiroshima, Japan. The news stories said there had been a test in the New Mexico desert. A check of the calendar showed that what she and the bus driver had seen that night was the flash from the Trinity Test.

Meanwhile, Bud was still stuck in Europe wondering, along with many others, why they weren’t being sent home and released now that the war was over. He may not have known the Army was working on the logistics of shipping them all from the European to the Pacific Theater. Bud returned home five months later, and my parents were married on Christmas Eve, December 24th, 1945.

The atomic test 15 seconds after detonation July 16, 1945
The Trinity test was the first ever test of a nuclear device

Sixty years later, in July of 2005, my wife and I joined in the event at the National Atomic Museum commemorating the Trinity Test and the beginning of the Atomic Age. It started the night before. We ate dinner with an older couple; she lived through the bombing in Germany as a young girl, and he had seen the Trinity flash on his way to go fishing outside Roswell. There were 1940’s cars in the parking lot, and wartime fashions were shown. The meat of the evening was a panel discussion (more a series of presentations) by two historians and two men who had been part of the Manhattan Engineering District — the Army’s part of the atomic bomb development program more broadly known as the Manhattan Project.

The next morning, on the sixtieth anniversary of the test, we were on one of the event’s three buses. The White Sands Missile Range had the site open for the anniversary. (Normally, it’s only open to the public on two Saturdays a year — one in October and one in April.) We were at Stallion Gate when it opened, and drove in to the McDonald Ranch house where the plutonium pit was assembled. We then spent some time at Ground Zero, before having green chile cheeseburgers at the Owl Cafe in San Antonio (where Manhattan Project people often ate on their way back and forth between the site and Los Alamos) before returning to Albuquerque.

One of the benefits of going as part of the group from the National Atomic Museum was that we weren’t just on our own looking around. Panel members from the night before spoke at the locations, giving us more of a picture of the conditions of sixty years ago. We also heard at least parts of interviews by various press organizations.

At the ranch house, an historian from the museum gave a picture of the camp that existed nearby at that time. He noted that the well and windmill could produce only about a gallon per hour of not very good water — which was why water for the several hundred people at the camp was trucked in. The one luxury was the stock tank, which was used as a swimming pool. Herb Lehr, who in 1945 was a sergeant in the Special Engineering Detachment, recounted bringing the plutonium pit (then the world’s supply of plutonium) down from Los Alamos, and told something of the checkout and assembly process. He noted that the markings on the door (clean your feet, don’t track in dust, etc.) were not authentic because they were done in chalk in 1945, while the ones you see now are painted on. At the request of some of the press representatives, he reenacted for the photographers how he took the assembled pit from the ranch house to the car (a 1942 Plymouth obtained new in 1945) to deliver it to the tower at Trinity Site Ground Zero.

Lehr also told of the hiccup in everyone's heartbeats as they attempted to load the pit into the rest of the device on the tower. Attempted — it didn’t fit, though the same pieces had fit at Los Alamos. The team lead said to just stop and they left it where it was, in contact with the outer uranium sphere, while they thought it through. A few minutes later, it slid in a fraction of an inch, and they realized they had a thermal problem. The plutonium core and the part of the unit near it were hot to the touch; the sphere had overnight cold. As the core heated the section of the sphere near it, its thermal expansion allowed the unit to slide in. Over a half hour or so the unit was assembled.

The historian speaking at Ground Zero (Ferenc Szasz, author of The Day the Sun Rose Twice) focussed on the difficulties in actually performing the test. This included worrying whether the night’s thunderstorms would clear before morning, and needing the wind to come from the proper direction. General Groves directly threatened the meteorologist that night, but fortunately the weather worked out well. That still left the question of whether the device would work properly, and with what kind of explosive yield. Of course, it did work — as everyone who saw the flash can attest.

That made me think of the tale told me years ago by people who had been in the Manhattan Project. Enrico Fermi was among those outside the blockhouse when the Trinity Test took place. After the initial radiation flash, he stood up and started dropping small pieces of paper. When the shock from the detonation arrived, the piece of paper that was in mid-air was moved and fell away from the rest. Fermi measured how far it was moved by the shock and, in just a few minutes, computed an estimate of the test’s explosive yield that was almost as good as the value that came days later from analyses of the experiment’s instrumentation.

Back at Ground Zero, Szasz noted that the inner fence surrounds the area where the test’s fireball touched the ground, where the trinitite was created. (Trinitite is glass created from the sand there by the heat of the Trinity Test fireball, all of which was later buried.) He also said that area was used to determine the detonation altitude that should be used in the attacks on Japan, both to maximize blast and shock effects on the cities from the atomic explosions and to avoid having the detonation fireballs reach the surface. Keeping the fireballs from touching the ground was necessary to minimize nuclear fallout from the explosions so the cities (and the areas downwind) would not be overly dangerous (longer term) either to their surviving residents or to invading U.S. soldiers — and so they would be better able to recover when the war was over.

On the bus ride home, I thought about the wartime focus that allowed a new weapon — a new class of weapon — to be used in the war just three weeks after the Trinity test showed it would work. That’s a very different timeline from what we see today. But it did bring the war to an end.

The National Atomic Museum hosted another event, three weeks after this one, that had as its focus the use of these new weapons during the August missions of the Enola Gay and Bock's Car that dropped atomic bombs on Hiroshima and Nagasaki.

More information on the Trinity test and site can be found at the following web locations (among others):

UPDATE: Links added in penultimate paragraph, and for Szasz’ book, in August.

1 comment:

Anonymous said...

hello wonderful site you have on the trinity project. i have been fascinated with "trinity" for some time now.
one question though: what did ken bainbridge say to oppenheimer after the explosion?
e-mail me if you