“We all aged ten years until the plane cleared the island.”

by Alex Wellerstein, published August 22nd, 2012

The island of Tinian is somewhat of an amazing thing. This small — 41 square miles – member of the Marianas served the the jumping-off point for the late-World War II American bomber raids against Japan. In this capacity, it was also the launching spot for the B-29s that used the first atomic bombs.

View of WWII-era Tinian, from the air

During World War II, Tinian was nothing less than a gigantic airbase carved onto a tiny, relatively flat island, one that had been hard-taken from the Japanese. There was hardly anything else to the island but runways, troop housing, and all of the buildings required for a massive military airport. "Massive" doesn't really cut it, though: imagine an airport that had to support a thousand B-29 Superfortresses, taking off for raids of 100 planes at a time.

The Manhattan Project sent a contingent of some 50 people to Tinian for the atomic bomb work. At least a third of them were civilian scientists. It was an impressive group: two of the scientists involved in bomb assembly would later win Nobel Prizes. One of these was Norman F. Ramsey, who passed away only last November, the assistant chief to the Los Alamos contingent.

Sometime after the Nagasaki run, Ramsey wrote a 12-page, handwritten letter to J. Robert Oppenheimer with his thoughts on how the operation had gone, and his thoughts for future bomb improvements. (The letter is undated, but it is clearly written sometime after August 20.) It's a gripping read, one that conjures up the grittiness of the Tinian experience. The parts that are most interesting are those that concern Ramsey's fears on the days of the bombings.1

Click to view PDF. Note that Ramsey hand-write "Secret" at the top of the page — secrecy without a stamp is a tedious business!

The letter begins with Ramsey lamenting the fact that he can't communicate with Los Alamos. As the chief scientist of the Tinian operation, Ramsey had sent numerous reports to Los Alamos, some even to Oppenheimer by name. It was evident, though, that Los Alamos was not receiving them — they were asking questions that had been explicitly already answered. So Ramsey resorted to these hand-written, hand-carried letters, "only means of communication with you in which I have any real confidence." I'm not sure what caused the communication glitch — DC would have been a complete mess at that point in things.

Ramsey then turns to the real meat of the letter:

Our experience in the delivery of the Fat Man has convinced almost all of us of the importance of one much needed improvement. It is in my opinion essential that any atomic bomb to be used in any fair quantity must be capable of being completely protected against even a slight possibility of a nuclear explosion being detonated by fire in take off of the aircraft. This will be particularly true later when atomic bombs are available in sufficient quantity that one can not safely gamble the safety of the base on merely the low probability of a fire on a single takeoff and when one can afford even a small loss of reliability to ensure the protection of the home base.

This "one much needed improvement" is a biggie — Ramsey was pointing out that if an atomic bomb of the Manhattan Project vintage caught on fire, it would very possibly detonate with a nuclear yield. This was no trivial matter. The Little Boy bomb was notoriously unsafe (not only could it easily accidentally detonate, but if it merely was dropped into salt water it would become a dangerous, uncontrolled nuclear reactor), and the Fat Man bomb, even with its complex firing mechanism, was still not very safe by later standards. Los Alamos would actually spend quite a long time trying to make sure that its bombs were reasonably safe from accidental fires or plane crashes.

Norman Ramsey on Tinian. From the Emilio Segrè Visual Archives, AIP. Unrelatedly, but an awesome photograph: Norman Ramsey, age 5, celebrating Washington's birthday.

This concern was rooted in Ramsey's personal experience of life on Tinian:

Only twice since I have been here have I been even slightly worried or nervous but both of these times the intensity of my worry made up for the relative calm of the other periods. ...[T]he worst period was that between the time the B-29 engines with the Fat Man were cranked up and the time the plane was well clear of the island. The night before the takeoff four planes in succession crashed in takeoff at the other end of the island — in fact the situation got so bad a mission of 100 planes was cancelled after only 30 got off the ground. Since I have been here I have watched several fires resulting from crashes. By actual timing a very intense gasoline fire continues for over twenty minutes. Six of eight fire engines working on such a fire don't even making a dent. After witnessing such fires and after having sweated out one FM [Fat Man] atomic bomb take off, I can’t urge too strongly the importance of complete nuclear safety in take off for future models. … The one FM take off has been my most unpleasant experience since joining the project. … We all aged ten years until the plane cleared the Island.

Ramsey was worried about atomic bombs catching on fire because in his experience it seemed like an awfully real possibility.

Has any historian contemplated what would have happened if the Enola Gay, instead of making it to Hiroshima, had crashed while taking off, setting off a nuclear explosion on the most important forward airbase in the Pacific Theater? I would have done quite a number on the US bomber capabilities, to say the least. Talk about your counter-factual possibilities.

Ramsey also offered up some concrete suggestions to making the bombs safer:

The only sure ways I have been able to think of is a trap door model with a cylindrical plug through the HE so that the active material can be inserted in flight or the insertion of neutral material in the open space of a non-Christy. I realize the difficulty of this especially with a non-Christy model. However, I feel that this feature is so important that with future great abundance of active material even a loss in efficiency and reliability to achieve it is justified.

HE means high-explosives; Ramsey is suggesting that they could do in-flight insertion of the fissile material (that is, only put the plutonium in once the plane has cleared the most dangerous part of the flight — the takeoff) which is in fact what they did in the next generation of nuclear weapons. Below is a Mark 5 bomb from the early 1950s showing how easily you could open it up to plunk in the plutonium:

Climb on in!

It's not a bad solution to the problem, except that it limits what you can do with the bombs. Most later bombs and missiles became sealed-pit weapons — you don't have someone up there on the top of the ICBM trying to insert a sphere of plutonium — which introduces its own safety concerns.

Ramsey's other suggestion was to put a solid (non-radioactive) material inside the center of a hollow bomb core. The Fat Man core was a "Christy"-type core, meaning a completely solid plutonium mass with just a tiny hole for the neutron initiator. (So-named after Robert Christy, who proved that you could do such a thing.  Edward Teller later claimed to have come up with the original idea, interestingly enough, inspired by his work with George Gamow on the compressed iron core of the Earth, but there's no evidence that I've seen that he told Christy about this. I met Christy some years back and asked him if he minded having his name associated with such an invention — he said he didn't mind.)

Basically if you put a bunch of metal inside a hollow plutonium core, it won't be able to compress into a solid mass, and thus shouldn't be able to become critical. It's a clever idea — the US apparently did this with the super-dangerous Mark 18 nuclear (the all-fission Ivy King device, which had a lot of HEU in it), putting an aluminum chain inside the pit until it was ready to drop.2  Brian Burnell reports that the British definitely used this sort of system in a number of their warheads.

The Fat Man bomb on Tinian: large, unwieldy, dangerous.

Ramsey continued the letter with some thoughts on future atomic basing requirements (he favors a centralized atomic base that could deploy bombs abroad when necessary), and the Nagasaki mission (which was something of a fiasco, though Ramsey concludes that it had gone, in the end, "remarkably well" — though he attributes much of that to luck). He finished on an interesting note:

Up to 19 August this was the most successful and best managed field party that I have ever seen or heard of. Everyone did a really excellent job and the whole organization worked beautifully as a unit. Unfortunately, the orders requiring us to stop on after 20 August made a bad anti-climax. However, since then we have tried to make the best of a sad situation. I hope that you can do something to get us home. Everyone deserves at least this much of a reward.

Imagine, the worst anti-climax being told not to prepare another atomic bomb for use! What I like about Ramsey's letter is it hammers home, again, how primitive the first atomic bombs were. We think of them as these paragons of sophistication, and in some ways, they were: they were built to previously-unheard of tolerances, and were as cutting edge as existed at the time. And yet, they were large, ad hoc, one-of-a-kind, dangerous devices. They required two future Nobel Prize physicists to assemble them. No surprise that the first work on the postwar stockpile was to "G.I. proof" the existing bombs — to make them something that could be assembled and used by people with considerably lesser talent.


  1. Letter from Norman Ramsey to J. Robert Oppenheimer (Undated, ca. August 1945), Library of Congress, J. Robert Oppenheimer Papers, Box 60, "Ramsey, Norman." Via the National Security Archive. A typed excerpt is available from them here.  []
  2. A related idea pushed by Matt Bunn is that of "pit stuffing," where you would insert a bunch of wire into stored pits, as a way of proving that you weren't planning on using them in bombs, and didn't want to make it easy for anyone else to use them in bombs. []

13 Responses to ““We all aged ten years until the plane cleared the island.””

  1. Jim says:

    Actually, I believe it says “the orders requiring us to stay on after 20 August”, which changes the meaning. I think they just wanted to go home.

  2. Alex Boxer says:

    In that fantastic first photo (which is from the North looking South) you can really see why the engineers decided the place looked like Manhattan. The main North-South road was (and still is) called Broadway; the North-South road on the right (West) is called 8th Avenue, and many of the cross streets are given names like 86th Street, etc.

  3. Mike Lehman says:

    I’ll hazard a guess or two at the reason why Ramsey was having trouble communicating with Los Alamos and Oppenheimer.

    Possibly, this was Groves at work, keeping his compartments tidy, but it could have been someone further up the food chain politically, if that was possible. At the same time that Ramsey and crew were on Tinian is when things with the Met Lab folks and others started rattling their chains about alternatives to using the bomb ASAP. All in all, that alone was reason enough to keep people who were charged with making the bomb usable from being influenced by things going on back in the Zone of the Interior. Can’t be having your scientists go on strike at the crucial juncture because of some lark. There may have been anxiety about possible collusion between the concerned scientists and those on Tinian?

    And who knows what kind of codes these really smart folks might be capable of embedding in an innocent looking letter? The military authorities on Tinian, who controlled things and generally seemed to have extended every courtesy possible to the team, still controlled the mail. Between ordinary secrecy at such a place and the special status of the 509th, a letter could take some lengthy detours before delivery…

    Makes me wonder if Ramsey was ever able to resolve what happened with the missing letters? I presume he took whatever precautions normally taken in using the mail securely, so that might raise a worry if they really didn’t show up at the other end eventually? Or maybe they were all sent regular mail and that raised curiosity on the part of the censors and mail handlers, given Ramsey’s position?

  4. Will Thomas says:

    Hi Alex, just got around to glancing at the actual letter. There’s a reference there to “Y” possibly moving to Pasadena. Was moving the Los Alamos lab to Pasadena ever a serious proposal? It’s an intrinsically intriguing possibility, but I also ask because I know that the Naval Ordnance Test Station in Inyokern had a satellite branch in Pasadena just after the war, and Ramsey mentions a possible link to a new atomic bomb wing in Palm Springs, so I was sort of wondering if there was a strong link between the LA region and the California desert inside the military at that time. Now that I think about it, there would have been a JPL-Muroc (Edwards) connection, too…

    • I have a vague feeling that I’ve seen some discussion of this before, but I can’t remember where. Los Alamos was obviously recognized as quite out of the way, so it wasn’t a given that it would stay in rural New Mexico after the initial need for absolute secrecy had passed (which is to say, the point at which the purpose of the lab was itself a secret). Pasadena was considered as a highly possible original site for Y when they were siting it in 1942, and as you note had the Inyokern site in proximity, so it isn’t too surprising that it would have been floated as a possible postwar site for bomb development.

      It would be interesting to look into the debates over moving Los Alamos. I wonder what kept it there? (Probably just sunk costs.)

      • Alex Pournelle says:

        Don’t forget that greater LA was indeed integral to later atomic testing–the secret Hollywood lab, including 100,000 square feet of studio and cutting-edge development equipment, was built on Lookout Mountain Road off Laurel Canyon in the 50s and served as the post house for all the film coming out of NV.

        That this was also the site of Heinlein’s “And he built a crooked house” is reality coming just a bit too close to science-fiction, in my mind.

  5. […] In my last post, I talked about what the island of Ticnian was like in World War II, when it served as the launching point for strategic bombing raids on Japan — including the bombings of Hiroshima and Nagasaki. […]

  6. We have chart of Tinian Saipan channel where we believe as many as 50 B-29’s are located. Crashed on Take Off. Don Farrell on Tinian is working with Congress to get a portion of Tinian annexed into a National Park. The Marines just cleared almost 70 years of jungle off North Field. The BOMB PITS are now encased in Stainless Steel and Glass. We are trying to preserve Tinian’s World War Two significance. Wayne Baumunk, Coral Reef Marine Center, Tamuning, Guam 96913

  7. Alex Pournelle says:

    Oh, and the ‘torpedo factory” annex in Pasadena, complete to its now-decommissioned siding, has been turned into a self-store, its formerly industrious multi-story lab/warehouse/manufacturing space cut up into so many large storage rooms.

    Peace is heck.

    • Joel T says:

      Hey Alex, I am digging around the internet and attempting to do a little research, I was just wondering if you knew anything about the Pasadena Annex and to what extent things went on there. I understand they had the largest government budget at the time with $2M and brought in bizarre things such as dolphins. Would love it if you could shed more light on it. I apologize if I am not keeping to the thread.

  8. Roger Banks says:

    My father, a mechanic in the Marine anti-aircraft division there, told of watching those civilians wheeling around these “things” and practicing loading them. A fellow marine commented on the curious extra security “I betcha couldn’t get anywhere near that thing.” On that dare, Dad went over and started BS’ing the Army guard, and then stuck out a hand and leaned up against it (presumably Fat Man from his description.) After the spectacular reports from Hiroshima, they couldn’t get anywhere near it again!

  9. […] threat of nuclear weapons accidents isn’t a new one. Even in 1945, Los Alamos physicists sweated when contemplating all that could possibly go wrong with their bombs, if they went off at the wrong place or the wrong time. Or didn’t go off at all. That’s […]