Posts Tagged ‘Tinian’

Visions

The plutonium box

Friday, March 28th, 2014

I’ve found myself in a work crunch (somehow I’ve obligated myself to give three lectures in the next week and a half, on top of my current teaching schedule!), but I’m working on some interesting things in the near term. I have a review of Eric Schlosser’s Command and Control coming out in Physics Today pretty soon, and I’ll post some more thoughts on his book once that is available. And I have something exciting coming up for the 60th anniversary of Oppenheimer’s security hearing.

In the meantime, I wanted to share the results of one little investigation. I’ve posted a few times now (Posing with the plutoniumLittle boxes of doom, The Third Core’s Revenge) on the magnesium boxes that were used to transport the plutonium cores used for the Trinity test and the Fat Man bomb:

The magnesium cases for the world's first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core. Center: Luis Alvarez at Tinian with the Fat Man core. Right: The third core's case at Los Alamos, 1946.

The magnesium cases for the world’s first three plutonium cores. Left: Herb Lehr at Trinity base camp with the Gadget core. Center: Luis Alvarez at Tinian with the Fat Man core. Right: The third core’s case at Los Alamos, 1946.

Just to recap, they were a design invented by Philip Morrison (the Powers of Ten guy, among other things), made out of magnesium with rubber bumpers made of test tube stoppers. They could hold the plutonium core pieces (two in the case of the Trinity Gadget, three in the case of Fat Man), as well as neutron initiators. Magnesium was used because it was light, dissipated heat, and did not reflect neutrons (and so wouldn’t create criticality issues). All of this information is taken from John Coster-Mullen’s Atom Bombs, an essential book if you care about these kinds of details.

But all of the photographs of the box I had seen, like those above, were in black and white. Not a big deal, right? But I find the relative lack of color photography from the 1940s one of those things that makes it hard to relate to the past. When all of Oppenheimer’s contemporaries talked about his icy blue eyes, it makes you want to see them as they saw them, doesn’t it? Maybe it’s just me.

The only place where I almost saw a color photo of the box is in a photo that the late Harold Agnew had taken of himself on Tinian. It’s one of a large series of posing-with-plutonium photos that were taken on the island of Tinian sometime before the Nagasaki raid. Only this one is in color! Except… well, I’ll let the photo speak for itself:

Harold Agnew with plutonium core redacted

Yeah. Not super helpful. This was scanned from Rachel Fermi and Esther Samra’s wonderful Picturing the Bomb book. They asked Agnew what had happened, and he told them that:

I was in Chicago after the war in 1946. The FBI came and said they believed I had some secret pictures. They went through my pictures and found nothing. Then like a fool I said, “Maybe this one is secret.” They wanted to know what that thing was. I told them and they said that it must be secret and wanted the picture. I wanted the picture so they agreed if I scratched out the “thing” I could keep the slide.

Thwarted by nuclear secrecy, once again! You can try to look extra close at the scratches and maybe just make out the color of the “thing” but it’s a tough thing to manage.

Ah, but there is a resolution to this question. Scott Carson, a retired engineer who posts interesting nuclear things onto his Twitter account, recently posted another  photo of the box — in color and unredacted! His source was a Los Alamos newsletter from a few years back. It is of Luis Alvarez, another member of the Tinian team, in the same exact pose and location as the redacted Agnew photograph… but this time, un-redacted! And the color of the box was…

Luis Alvarez with the Fat Man core, Tinian, 1945.

…yellowNot what I was expecting.

Why yellow? My guess: it might be the same yellow paint used on the Fat Man bomb. Fat Man was painted “a mustard yellow rust-preventing zinc-chromate primer” (to quote from Coster-Mullen’s book) that made them easier to spot while doing drop tests of the casings.

The box for the Trinity core doesn’t look painted yellow to me — it looks more like raw magnesium. Maybe they decided that the tropical atmosphere of Tinian, with its high humidity, required painting the box to keep it from oxidizing. Maybe they just thought a little color would spruce up the place a little bit. I don’t know.

Does it matter? In some sense this is pure trivia. If the box was blue, green, or dull metallic, history wouldn’t be changed much at all. But I find these little excursions a nice place to meditate on the fact that the past is a hard thing to know intimately. We can’t see events exactly as they were seen by those who lived them. Literally and figuratively. The difficulty of finding out even what color something was is one trivial indication of this. And the secrecy doesn’t help with that very much.

Visions

Silent Nagasaki

Friday, February 7th, 2014

Teaching and other work has bogged me down, as it sometimes does, but I’m working on a pretty fun post for next week. In the meantime, here is something I put together yesterday. This is unedited (in the sense that I didn’t edit it), “raw” footage of the loading of the Fat Man bomb into the Bockscar plane on the island of Tinian, August 9th, 1945. It also features footage of the bombing of Nagasaki itself. I got this from Los Alamos historian Alan Carr a while back. I’ve added YouTube annotations to it as well, calling out various things that are not always known.

You have probably seen snippets of this in documentaries and history shows before. But I find the original footage much more haunting. It was filmed without sound, so any sound you hear added to this kind of footage is an artifact of later editing. The silent footage, however, makes it feel more “real,” more “authentic.” It removes the Hollywood aspect of it. In that way, I find this sort of thing causes people to take the events in the footage more seriously as an historical event, rather than one episode in “World War II, the Movie.”

I posted it on Reddit as well, and while there was some share of nonsense in the ~700 comments that it accrued, there was also a lot of expression of empathy and revelation, and a lot of good questions being asked (e.g. Did the people loading Fat Man into the plane know what they were loading? Probably more than the people who loaded Little Boy did, because they knew what had happened at Hiroshima). So I think some learning has happened, and I think the fact that this has gotten +100,000 views in just a day is some sign that there is quite an audience out there for this sort of stripped-down history.

There is also Hiroshima footage, but it isn’t quite as good, on the whole. It is largely concerned with the crew of the plane taking off and arriving. Which is interesting, in a sense, but visually doesn’t mean much unless you know who everybody is.

There is a lot of Trinity test footage as well which I will upload and annotate in the future as well.

Until next week!

Visions

Little boxes of doom

Wednesday, October 23rd, 2013

I was at a (very interesting) conference last week and didn’t get a chance to do a regular blog post. I’ll have a real post on Friday, as usual, but I thought in the meantime people might enjoy this little passage I came across in William L. Laurence’s Dawn Over Zero: The Story of the Atomic Bomb (1946):

The secrecy frequently led to tragicomic situations. A trusted courier was dispatched by automobile to deliver a small box of material, the nature of which he was not told, to a certain locality several hundred miles away. He was cautioned that at the first sign of any unusual behavior inside the box he was to abandon the automobile in a hurry and run as far away from it as his legs would carry him.

The magnesium box used for transporting the plutonium core to the Trinity site. Via Los Alamos.

The magnesium box used for transporting the plutonium core to the Trinity site. Via Los Alamos.

Our courier asked no questions and went his way, taking frequent glances at the strange box behind him. Things went well until he came to the middle of a long bridge. Suddenly, from directly behind him, came a terrific boom. Out of the car he dashed like one possessed, running faster than he had ever run in his life. Out of breath and exhausted, he stopped to examine himself to make sure that he was still in one piece. Meantime a long line of traffic had gathered behind his driverless car and the air was filled with the loud tooting of impatient motorists.

Slowly he made his way back to his automobile and found to his amazement that it was still all there. Peering cautiously inside, he was even more amazed to find his precious box on the same spot as before. He was used to strange things, this courier, so he took his place at the wheel and was about the continue on his mission when once again he heard a loud boom directly behind him.

Once again he made a dash for his life, heedless of the angry horns that by this time were sounding from a line more than a mile long. Still exhausted from his previous mad dash, he nevertheless managed to put a considerable distance between himself and his mysterious box.

Eventually he made his way back, to find his car and his box in the same spot where he had left them. This time, however, he found an irate traffic officer waiting for him. Beyond showing the officer by his credentials that he was a Government employee, there was nothing he could tell him. It turned out that there had been blasting going on underneath the bridge.

Who knows how much of the story is true and how much of it is embellished by either Laurence or the original teller, but I thought it was highly amusing. One suspects, by the description of the box, the particular safety concerns, and the distance, that they are talking about the movement of the Trinity core from Los Alamos to the Trinity site.

John Coster-Mullen, in his fantastically interesting Atom Bombs (a newly-updated copy of which he recently sent me), has a somewhat related anecdote from the plane that transported the Fat Man core to Tinian in late July 1945: “During the flight to Tinian, they ran into a storm. [Raemer] Schreiber was sitting in the co-pilot’s seat and one of the guards came forward and tapped him nervously on the shoulder. ‘Sir, your box is bouncing around back there and we’re scared to touch it.’ Schreiber went back, corralled it, got a piece of rope and tied it to one of the legs of the cots.”

Visions

Going Back to Tinian

Friday, August 24th, 2012

In my last post, I talked about what the island of Tinian 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.

A physicist friend of mine from graduate school, Alex Boxer (who currently consults the Navy about submarines, and has his own history of science blog), recently took a vacation to Tinian, and took a ton of photographs. He’s given me permission to re-print some of them here, along with some of his comments on them (which are in italics).

You can begin your virtual tour of Tinian with this movie of what it’s like to fly there from Saipan.  The planes are just little 6-seater prop-planes, and the flight is probably a grand total of 10 minutes.  In this movie (sped-up 2x to reduce its size) you can see the whole island and what’s left of the North Field runways.

There’s very little to see that’s bomb-related — it’s striking, really, it’s almost as if the US military was never there.  The only buildings which remain from that era are Japanese installations.

A random Japanese propeller located on the southern end of the island:

At North Field (located, sensibly enough, at the North end of the island) there are several Japanese buildings:

Description from a placard outside the building:

This two-story building was the World War II headquarters of the Japanese Navy’s 1st Air Fleet (Base Air Force of the Marianas), commanded by Vice Admiral Kakuji Kakuta. … Admiral Kakuta’s airfields in the Marianas and Iwo Jima served as staging areas for moving aircraft to southern Pacific battle areas and for attacks on American ships. By July of 1944, the airfields directed from the 1st Fleet headquarters had been captured or destroyed. What remained of Admiral Kakuta’s airplanes was destroyed in the naval battle of the Philippine Sea a month before the battle of Tinian. … When Americans captured Ushi Field, the headquarters building was abandoned and Ushi Field was a “ghost field” of abandoned airplane wrecks. The fate of Vice Admiral Kakuta is unknown, but was probably suicide or death. His last radio message to Tokyo was on July 30 as the battle of Tinian was nearing its conclusion. The massive concrete headquarters building was damaged by American artillery, but the building was repaired and used by American military officers after the invasion.

Another placard:

This building was the control center for the Japanese Navy’s 1st Air Fleet operations on Tinian, directing traffic on the runway to the south. It contained an office, the operations room, and a generator room. This is a standard design for World War II Japanese air operations buildings, with other examples located on Saipan and Chuuk. … The building was repaired and used as a control tower by the 20th Air Force after the B-29 runways of North Field were constructed here.

One more placard:

This massive power plant was probably build in 1939-1940 as part of the Japanese military construction of Ushi Field. the “bombproof” building was constructed of reinforced concrete and had steel shutters covering the windows. The building housed a 200 kilowatt power plant run by diesel fuel.

 And here’s what you’ve been waiting for: bomb-pits! — The pits where Little Boy and Fat Man were loaded into the B-29s that dropped them on Japan.

I was somewhat dismayed at how little there was to see.  It’s just two pits now under glass enclosures, somewhat like the entrance to the Louvre.  The glass was also highly reflective which means that most of my photos didn’t come out very well.

The loading pit is under the glass enclosure.

Tinian was fantastic because it was one of the emptiest and quietest places I’ve ever been.  I felt like I had the whole place to myself.  However, there is nominally a tourist industry there which includes a rather shady hotel/casino.  The tourists are mainly from Asia and Russia — there’s hardly anyone from the mainland US (a brief look at a map of the Pacific will make it clear why this is so).  Anyways, our silent day was enlivened by a large tour-bus.  I’m certain that these tourists are not Japanese; I’m almost, but not quite 100% certain that they are Chinese.

Interjection: just to compare, here are the actual loadings of Little Boy and a Fat Man test unit.

Or you could fly all the way to Tinian, and see the same sort of photos in the actual bomb pit:

Back to Boxer:

And as much as I’m an aficionado of atomic (or, rather, nuclear?) history, that wasn’t the main lure for me.  Here’s what I really wanted to see on Tinian:

These are parts of the House of Taga:

The site is the location of a series of prehistoric latte stone pillars which were quarried about 4,000 feet south of it. Only one pillar is left standing erect. The name is derived from a mythological chief named Taga, who is said to have erected the pillars as a foundation for his own house. Legend says Chief Taga was murdered by his daughter, and her spirit is imprisoned in the lone standing megalith at the site.

I have to admit, I wasn’t aware that the only other tourist site on Tinian was just about as grim at the first atomic bomb loading pits.

And, just for fun, here’s a lovely photo of a Flame Tree:

Very cool. Let’s all give a little round of virtual applause for Dr. Boxer and maybe visit his website while we’re at it.

Now, you might be thinking — well, Tinian’s heyday has come and gone. And you might be right. But there’s been some interesting news about it from earlier this year:

Japan Self-Defense Forces officials will arrive today to discuss with CNMI officials their plans for Tinian where two-thirds of land are already leased by the U.S. Department of Defense, and the discussions could center around Japan’s plan to help fund a U.S. military base on Tinian or the training or stationing of their own forces there.

That’s right — there’s a chance (perhaps not a great one) that Tinian might yet be the site of a military base. What would be more appropriate — or inappropriate? — than Tinian becoming a joint US-Japanese military site?

Redactions

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

Wednesday, 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.

 

Notes
  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. []