Restricted Data

I received word recently that John Coster-Mullen passed away in the early hours of Saturday, April 24, 2021. He was 74 years old.¹ He had been suffering from ALS (amyotrophic lateral sclerosis, a neurodegenerative disease) for the past year or so, I have been told, and it had been a very difficult one as he lost physical and cognitive capabilities. He died peacefully, surrounded by his family, according to his wife.

Illustration of John Coster-Mullen and the Little Boy bomb, from a 2008 profile in the New Yorker by David Samuels.

I don’t know off-hand exactly when I started talking to John. A look through old e-mails suggests that in 2006 we had been talking, but that those e-mails reference earlier conversations. My guess is that we had been in touch in 2005, when I was working on my paper on how people draw atomic bombs. I had interviewed Richard Rhodes very briefly over the phone, talking about how the diagrams for Little Boy and Fat Man were made for The Making of the Atomic Bomb (they were drawn by his son), and Rhodes had mentioned John’s work and how amazing it was. Around that time I probably bought John’s book and got in touch with him, and we began exchanging documents as well. Around that time I was also working on my atomic patents work, and I sent some of those to him very early on as well, knowing he would appreciate them. 

Over the next 15 years or so, we exchanged quite a bit of documents, I acquired three versions of his book, Atom Bombs, and we got to spend some time together in person at the Atomic Heritage Foundation’s conference for the 70th anniversary of the Manhattan Project. He was always generous and excited. He clearly really enjoyed that he, a truck driver (among other things), was producing research that academics from places like Harvard and Princeton thought was important and valuable. 

One of the several copies of John’s self-published Atom Bombs I have. John never “finalized” the book, and was always updating it over the years.

I enjoyed John as a friend, correspondent, and as a subject of study. John is what I call a “secret seeker” in my book, someone who — for whatever reason — is driven towards learning “nuclear secrets.” I find secret seekers (in which I would include Chuck Hansen, Howard Morland, and Carey Sublette, among others) very interesting. Their motivations and methods vary quite a bit, as do their choice of subject. Hansen wanted to know everything of course, but Morland was focused on the H-bomb, and John the specifics of Fat Man and Little Boy.

While some secret seekers, like Morland, have explicitly political agendas in doing this (often related to exposing the futility of secrecy), for others that approach took a back-seat to other interests. With John, I never got the sense that he was strongly motivated by the politics of secrecy, though he sometimes could sound like that when he got irritated with the Department of Energy, or when he got annoyed when people would imply that he was doing something potentially dangerous. Sometimes he would give the old Ted Taylor line, that the surprising thing about the atomic bombs is that they aren’t that hard to build (if you have the fuel, etc.), but it always struck me that he was somewhat infatuated with the history of World War II, and the people who had made and used the bombs, and saw this as the tiny area where someone with his interests and skills could make a real contribution. I think discovering “the secret” for him was more about proving himself as a researcher than probably any big statement about secrecy. Over the years I’ve gotten various documents from him trying to explain himself, and to my eye they come down to a sort of love for the work, the topic, and the people — one that only grew over time and he had more exposure to all three. 

John would occasionally send me various ideas, documents, drawings as he updated his thoughts about the specifics of these bombs. My favorite is the above video that he sent me in 2008 (I don’t know when he made it, exactly) that he made by putting a snake camera inside a postwar Little Boy casing on display at the International War Museum. You can see it moving through the bomb casing from back to front. John would use this kind of hard-won, “nuclear archaeology” data to fill out the minute details of how these bombs were built. This was, for John, clearly a labor of love. It’s a weird thing to suggest that he loved these bombs and the men who made them, but I think he did. 

I respected John’s work a lot. His overall view of the bombings was very much in the standard, “they had to be done, they were a good thing” interpretation, but we could agree to disagree on such things. His technical account of the weapons, and of the procedures necessary to get them working, is unparalleled. His book is my reference for whenever I need the micro-level details of shipment and assembly of the weapons, or of design information relating to them. His book inspired me to write my piece on Nagasaki for the New Yorker in 2015; he had the best account of the chaotic details of that bombing that I ever had read. I suspect my interpretation of them was quite different than his! But our friendship and mutual respect could accommodate such differences in views. Stan Norris reviewed his book in the Bulletin of the Atomic Scientists over a decade ago, and put it so aptly:

Nothing else in the Manhattan Project literature comes close to his exacting breakdown of the bomb’s parts. Coster-Mullen describes the size, weight, and composition of many of Little Boy’s components, including the nose section and its target case; the uranium-235 target rings and tamper; the arming and fuzing system; the forged steel 6.5-inch-in-diameter gun barrel through which the uranium-235 projectile was fired at the target rings; and the tail section—to cite just a few.

John’s biggest “discovery” was that the Little Boy bomb’s internal workings were somewhat opposite of what everyone else had assumed in the “open community” for decades on end. Instead of a smaller projectile of enriched uranium being shot into a larger target of it to form a supercritical mass, it was the other way around: the projectile was the large part (a set of hollow rings), the target was the small part (a solid “spike”).

One version of John’s depiction of the innards of Little Boy that he sent me (this one from 2017). He told me he drew these diagrams in MS Paint! The hollow projectile is labeled S; the target spike is labeled H. Most of the changes over the last few years were his interpretation of how the tamper pieces were put together.

The profile of John by David Samuels in The New Yorker from 2008 explains his evidence; the main idea was “leaked” to him by Harlow Russ, and it jibed with other data he had. I originally treated this as the same sort of “maybe” speculation that surrounds lots of nuclear topics, though several years later I found a document which to me totally cemented the idea as true (which, of course, I immediately sent to John, and he immediately added it to the hoard of documents in his book).² John made it more fun for me to look at these detailed technical documents, because he gave me something new to look for.

Looking through my e-mails with John over the years, it’s plain how generous he was. He shared lots of things with me — not just documents and photographs, but texts of talks he was giving, comments from other researchers on his work, and even just silly e-mail forwards. He sent me the declassified guide on the fuzing system of the MK-3 atomic bomb that graces the cover of my new book. He would occasionally send me a new copy of his book if he thought my copy was too out of date. He sent me mysterious pieces of metal (bits of duraluminum, remnants of a non-nuclear bomb test, that he found in an unspecified desert), just as a little offering of friendship and camaraderie. He stayed in good touch until the last year or so; now I know why.

Here’s an excerpt from one e-mail sent in 2009. All underlining is in the original. It gives you a flavor for his working style, and the joy he took in this work.

Dear Alex,

Here is something to open up your eyes.  

I spent all day last month at the Atomic Museum in Albq during the 509th reunion. At the end of the day one of their researchers gave me a CD containing about 800 declassified photos; some old, some newly declassified. This is part of a set of 6 or 7 CD’s that LANL sent to all the museums a few years ago so they would have copies. These are low-rez thumbnails and I made a selection of several dozen that this person burned to a CD for me in their spare time and sent a few weeks later. I went through the thumbnail CD and found this one at about midnight one night. It reveals something spectacular and hitherto unseen.

I was quite shaken and think I woke all my neighbors with my startled yell.

Even a month later I’m still sitting here with my jaw in my lap. Picture TR-229 shows the inside of the tent under the Trinity tower with the sphere on the left (Slotin leaning against it) and the litter with the capsule on the right side. This litter is the one Daghlian and Lehr placed into the 1942 Plymouth in front of the McDonald Ranch. The litter is sitting on a crate with the wood box cover off and the completed Pu filled tamper cylinder sitting strapped to the litter. It can be clearly seen. I’m stunned!!!!!!!!!!!!!!!!!!!!!!!!

His work will live on. His wife, Mary, told me that his children are helping fulfill orders on his book still. John always resisted working with a publisher, both because he didn’t want to edit it down (as he feared he’d be asked to do), and also because it was never a finished project. Maybe now it’s ready to be typeset once and for all. We’ll see. 

A photograph I snapped (with my terrible phone camera) of John in 2015, while I sat behind him at the Atomic Heritage Foundation conference on the 70th anniversary of the Manhattan Project.

My sense is that while I’m sure there was always one more detail to know, John basically accomplished what he wanted when it came to the history of Little Boy and Fat Man. He changed our knowledge of these weapons dramatically, and his samizdat book is considered quite authoritative on these matters. He never had a college education, but he got to give talks at universities, nuclear weapons laboratories, and rub shoulders with scholars and historical actors alike. He worked at this for nearly 30 years, and established himself as a generous, quirky, and unusual expert. I don’t talk about John much in my book — not as much as I’d like to, but there is only so much room — but I make a sideways acknowledgment that only in America could you have the phenomena of a truck driver whose hobby was to discover nuclear secrets. 

Rest in peace, John.

1. From interviews and his Facebook page, I gather his birthday was December 21, 1946. [↩]
2. The document in question is this one: C.S. Smith and I.C. Schoonover to J. Robert Oppenheimer, “Gun Fabrication Plan – Second Supplement to Memorandum of June 13, 1945,” (3 July 1945), Nuclear Testing Archive, NV0321050. It describes the final decisions about a small amount of cadmium plating that was put on the pieces of highly-enriched uranium to prevent premature fissioning. It describes a plating on the inner surface of the projectile and the outer surface of the target — something that only makes sense if the projectile is the hollow piece. [↩]

Tags: 2020s, Bomb design, Books, Fat Man, Leaks, Little Boy, Speculation

This entry was posted on Sunday, April 25th, 2021 at 6:41 pm and is filed under Meditations, News and Notes. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

Citation: Alex Wellerstein, "In Memoriam: John Coster-Mullen (1946-2021)," Restricted Data: A Nuclear History Blog, April 25, 2021, accessed December 22, 2024, https://blog.nuclearsecrecy.com/2021/04/25/in-memoriam-john-coster-mullen-1946-2021/.