Showing posts with label Freaky. Show all posts
Showing posts with label Freaky. Show all posts

Friday, December 14, 2012

Apollo 17 - 40 years, and still waiting

Colleagues,

40 years ago today, Gene Cernan was the last human to walk on another planet.



It had only been 11 years since Alan Sheppard had flown into space for a grand total of five minutes, atop a glorified bottle rocket. Cernan and his crewmates Ron Evans and Harrison Schmitt spent three days on the Moon.

To quote Tom Hanks (as Apollo 13 commander Jim Lovell), "It's not a miracle.  We just decided to go."

Man's reach must exceed his grasp, else what's a heaven for?

Tuesday, December 4, 2012

3 February 2012 – That’s no moon…

Colleagues,

You may recall that shortly before Christmas I sent around a message in which I discussed the design, developmental work and testing that had been done on the Vought SLAM - the nuclear ramjet-powered, H-bomb sowing flying leviathan that was one of many unbelievable but terrifyingly realistic weapons systems dreamed up by atomic eggheads in the 1950s and 1960s.  Not surprisingly, this little trot down memory lane sparked a good many comments, most of them concerning the sheer lunacy of creating something that carried a belly-full of nuclear weapons, irradiated anything it flew over, and had a virtually unlimited range.  In one subsequent conversation, however, the point came up that, with such maniacal inventions cluttering up our collective history, there didn't seem to be much point in unleashing speculation in an attempt to posit the sorts of innovations ("disruptive technologies", if you like) that might pop up in the future.  This is not to suggest that speculation isn't fun, just that there isn't much point in it - particularly when there's no way to predict where technology will go, and especially when we're so woefully ignorant about our own past, and haven't figured out how to deal with things that we ourselves invented half a century ago, but just somehow didn't get around to putting into production.  We don't have to go to the history of the space race for such examples; we only need to look into our own archives.

For example, we're all familiar with HEAT rounds - they've been around since WWII, and are fairly simple in concept.

The British PIAT - Projector, Infantry, Anti-Tank - relied on a HEAT warhead to (occasionally) penetrate enemy armour.  A HEAT warhead consists of an explosive charge with a conical well in the centre, lined with metal (usually copper).  The charge is initiated by a base fuze.  In the case of the PIAT warhead (below), the projectile is fired at a target; the extended probe on the nose fuze ("transit plug") transmits the shock of impact to the fuze at the base of the HE charge.  When the HE charge detonates, the shock wave compresses the copper cone into a jet of molten metal travelling at the speed of the explosion - roughly 7000 m/s in the case of a conventional TNT or Composition B fill.  The liquid metal jet penetrates the armour of the target and does corresponding damage to the interior of the vehicle, and its crew.  HEAT rounds are very effective, which is probably why they continue to constitute part of the basic load (along with kinetic penetration munitions, like APFSDS) of main battle tanks and armoured fighting vehicles even today.  They also continue to make fantastic infantry AT weapons; virtually all current light, medium and heavy AT missiles and rockets, from the venerable RPG-7 to the modern TOW2 missile use HEAT warheads.


Defending against HEAT rounds requires different strategies.  First, you can keep the jet away from your armour plate.  That means hanging something on your vehicle to make the incoming round detonate further away.  Second, you can keep the jet from forming; one way of doing so being explosive reactive armour panels, which detonate when the HEAT round strikes them, destroying the round as the jet is forming.  Third, you can thicken up your armour (bearing in mind the requirement that the vehicle still has to be able to move and carry stuff).  And fourth, you can try to disrupt the jet and prevent it from penetrating all the way through to the interior of the vehicle (which led to layered armour, with various materials sandwiched between plates to disperse the jet horizontally).
Research in the 1980s and later on took the HEAT concept somewhat further, into explosively formed projectiles (EFPs, also known as self-forging fragment projectiles).  During my first visit to Suffield as a staff officer back in the early 90's, I was shown test fragments and videos from trials on a new type of experimental munition: a scaled-up version of an EFP.  By thickening the conical well liner in the explosive charge, or by changing to a different, tougher metal than copper (e.g., iron), the charge, when detonated, would - instead of forming a liquid metal jet - compress the metal cone into a slug moving at very high speed.  The slug would not be affected by stand-off detonation mechanisms or explosive-reactive armour panels, and layering armour to disperse a metal jet horizontally wouldn't be much help. 
Moreover, you could make the slug big.  Really, really big.
 

THIS big.  That's from a test at Suffield back in the 90's.  I recall handling something like this during a visit.  It was more than a foot long and weighed about 30 pounds.  Imagine that thing coming at you at several thousand metres per second.  And the creation of them, by the way, is an exercise in perfect machining backed up by mathematics.  Here's an image from a DRES paper from 1995 (by one of our own colleagues - see note A) on modelling EFPs:

Note the similarities - and the caption which states that the mathematical models were confirmed by experimentation.  That hunk of metal started out looking like a wok about an inch thick, and after being whapped with a couple dozen kilos of HE, ended up looking like the lawn dart from Hell.  Math is awesome.
There's no point in going into too much more detail on EFPs, because that isn't what I really wanted to talk about in this message anyway.  I simply wanted to emphasize the fact that this technology is now old - so old that the Iraqi insurgents, al Qaeda, and other jihadist adversaries have adapted self-forging fragment technology to off-road mines and IEDs, and we're still having a heck of a time dealing with it.  What I'm getting at is that we don't need to invent science-fictiony "future" threats like "tunable weapons" and "gray goo nanobots" and "hyper-empowered individuals" if we're already facing things invented decades ago, but that have got us completely boggled.
Which takes me to today's topic - the Death Star.  Or at least the Soviet equivalent, Polyus. 
 

A few years back I penned a tech note looking at the arms control implications of space testing missions, specifically the October 2009 LCROSS experiment in which NASA slammed a rocket body into the Moon as part of its search for water on the lunar surface. The paper attracted its fair share of mocking laughter due to the title, which I wrote in jest ("Bombing the Moon"), but anyone who'd taken a moment to read the thing - it wasn't long - would have realized that I was trying to point out the implications of arms control treaties, agreements and regimes for otherwise legitimate space exploration and testing exercises, and vice versa. More knowledgable individuals with a higher security clearance who read that note would have recognized that I was trying to discuss in synecdoche a much more profound incident with significant legislative implications.

Of course, these days most folks don't seem to go in for specialized knowledge, and those who do often seem to lack the security clearance (or the simple interest) to delve deeper into important, paradigm-altering problems that actually impact us on a daily basis. People styling themselves "scientists" seem to prefer to fiddle with models rather than data and evidence, blathering on in bland, meaningless generalities devoid of any linkage to the real world rather than grappling with current problems. I guess that's easier and safer. Whether it's anything more than a complete and utter waste of time and taxpayer money, on the other hand...that's for other folks to decide.

But I digress. In the course of that tech note, I discussed the arms control prohibitions against space-based weapons, briefly mentioning the 1987 launch of an 80-tonne orbital object by the USSR.  This vehicle, it has been suggested, was to have been the forerunner of a series of orbital battle platforms intended to neutralize the US Strategic Defence Initiative systems (which of course were never deployed). 

Polyus failed to achieve orbit and ended up in the Pacific Ocean, and the Soviets never tried again - but the point is, they tried once.  Polyus wasn't some postulated "disruptive technology" or theorized "future threat". It was very real. 

And yes, I know the above picture has "MIR" on the side of the big black thing; according to the official article on Polyus from the Buran website, MIR space station modules were used in its construction.  Here's a pic of the vehicle on the launch pad at Baikonur in 1987; the "Polyus" name is clearly visible on the side (you can sort of see it in the colour pic above, too):


For the sake of reference, the Polyus vehicle in the image above is 40 m long, about 4 m in diameter, and weighed 80 tons.  The Space Shuttle Orbiter is 37 m long, and weighs about 70 tons empty (its gross liftoff weight is about 109 tons).  So this was no mere firecracker.

How real was all this?  Well, real enough that Mikhail Gorbachev showed up at Baikonur on 11 May 1987 to see the thing shortly before it was launched.


According to one news report, one of the purposes of Gorby's visit was to confirm that Polyus was not carrying any weapons.  Did it, or didn't it?  The actual story is a little hard to get a grip on; there are numerous pictures available from different archives, and various articles published by project personnel over the years tell different stories.  Schematics abound on the innerwebz:


 If your Russian is as good as mine, you won't have gotten any of that.  Here's an alleged translation, according to an article penned by one Ed Grondine:

There isn't much in the way of empirical support for Grondine's assertions.  Most of what is available in the public domain about Polyus comes from official websites (for example, Buran), which don't mention self-defence armaments, much less "nuclear space mines".  A lot of the funkier stuff comes from a 2005 article by Konstantin Lantratov, a former press officer in the Russian space industry, entitled "Star Wars That Didn't Happen".  According to the Buran website, for example, the Polyus vehicle carried ten separate scientific experiments - the first of which was testing the USSR's ability to orbit super-heavy packages...like Polyus.  Interestingly, the site contains dozens of photos of the spacecraft in the assembly stages; it appears to have been cobbled together out of spare parts:

The service block looked like a "Salyut" slightly modified for this task and was made up from parts of the ships "Cosmos-929, -1267, -1443, -1668" and from modules of MIR-2 station. In this block took place the management systems and on-board displacement, the telemetric control, the radiocommunication, the heating system, the antennas and finally the scientific installations. All the apparatuses wich not supporting the vacuum were installed in the hermetic section. The part of the engines made up of 4 propulsion engines, 20 auxiliary engines for stabilization and the orientation, 16 precision engines, as well as tanks and pneumo-hydraulics conduits. Lastly, the production of electricity was made by solar panels which were spread when Polyus was into working orbit. (Note B)

The size, design and components of the vehicle - not to mention the secrecy with which it was fabricated and launched (which was not at all uncommon during the Cold War, remember) - would naturally spark all manner of conspiracy theories.  The vehicle according to Buran contained large quantities (420 kg) of xenon and krypton in 42 cylinders of 32 L capacity, with an injector to squirt the gas into the upper atmosphere to "generate ionized signals with long waves".  Grondine argues that the purpose of this was to produce light by fluorescence, in order to signify that a container (possibly holding a nuclear space mine?) had been launched without generating radio energy, which could be tracked.  According to other sources (e.g., the always infallible Wikipedia), the gases were intended to be used to test, with the appearance of innocence, the venting apparatus for a zero-torque exhaust system for a 1 megawatt carbon dioxide laser intended to damage Strategic Defence Initiative satellites.
Grondine also commented, as many others did, on the "optically black shroud" covering the whole thing.  Painting a space object black is one way to make it more difficult to see via reflected light - although the point of doing so when you've got huge solar panels sticking out of the sides of the thing escapes me.  Also, painting it black would tend to make it hot, as it would absorb rather than reflect solar radiation; and unless the thing incorporated stealth technology, it would still be easily visible by radar, which is how SpaceCom tracks large orbital objects anyway.
The fate of Polyus was in any event not a happy one.  It was launched on 15 May 1987, two days after Gorby's visit to Baikonur ended.  The Buran website has a comical description of why the GenSec missed the launch:

The first launch of Energia and Polyus was so important for the direction of the party that the General Secretary of the Central Committee of the Communist Party itself, Mikhaïl Sergeevich Gorbatchev, went. However, it is well-known that any apparatus, so simple is it, have a strong probability of breaking down during a demonstration or in the presence of VIPs, this is why the Management committee had decided (on May 8) to delay the departure on May 15, under pretext of technical problems, knowing that M.S. Gorbatchev could not remain because it had a voyage to the head office of UNO at New York.(Note B)

Their precautions turned out to be well-founded.  Because the Energiya had been designed with hang-points for the Buran space shuttle system, Polyus had to use the same connection mechanisms.  This led to it being mounted backwards, i.e. with the main thruster engines facing forward, resulting in a complicated mission profile.  In order to achieve orbit, after about 8 minutes into the flight program, at an altitude of about 110 km, the Polyus would jettison its engine shroud, separate from the Energiya booster, and execute a 180 degree turn using its thrusters.  Once this was complete, about 15 minutes into the flight and at an altitude of about 155 km, it would fire its main engines periodically to level the craft, and eventually achieve a stable orbit at 280 km altitude, by about 30 minutes after launch.
That's not what happened.  Only one of the positioning thrusters functioned, and the Polyus, instead of making a 180 degree rotation, made a full 360, leaving the main engines pointing forward.  Instead of accelerating the craft into orbit, the engines decelerated it, and Polyus deorbited into the Pacific Ocean, reportedly landing in water that was several kilometres deep.  According to open sources, the spacecraft was never retrieved.
So, Polyus was real.  The Soviets really built it, and they really launched it.  Did they arm it? Was it supposed to be the first real space battle station?  Would it have worked?  A 1-megawatt laser isn't much in atmosphere, where blooming and attenuation quickly destroy beam coherence; but in space, it might be fairly effective over a reasonably long range.  Could it also have carried "nuclear space mines", presumably for use against US orbital assets?  I think a more important question is, could it have carried nuclear warheads as part of a fractional orbital bombardment system, or FOBS?  That was one of the big worries of the 1960s, and it was one of the key reasons that the US and USSR negotiated the 1967 Outer Space Treaty, which prohibited placing "nuclear weapons or other weapons of mass destruction" either in orbit or on celestial bodies.(Note C - and here we are back at the "Bombing the Moon" technical note again. Funny how this arms control nonsense keeps coming back to haunt us. Almost like it was relevant or something.) 
Would the Soviets have broken the OST? Well, when you can't figure out why somebody's doing what they're doing, or whether they're likely to be doing something they shouldn't, you've got two choices: pull a guess out of your nether regions (the preferred option for "analysts" who don't know anything about anything and think that history is "stuff that's in books"); or use actual evidence. In such cases, the only evidence we have to go on is historical precedent - i.e., what have the suspects done in the past, and why.  Would the USSR have abrogated the 1967 OST by placing nuclear weapons in orbit?  Well, they signed the 1972 Biological and Toxin Weapons Convention, which prohibited producing biological weapons...and then went on to build the biggest biological weapons complex in the world, churning out weaponized anthrax, smallpox, and a host of other pathogens literally by the metric tonne.  By the late 1970s, the USSR was consuming 400,000 fresh eggs per week simply to incubate the weaponized India-1 strain of Variola Major, and had developed refrigerated, heat-dissipating ICBM warheads specifically designed to keep viral and bacterial agents alive during re-entry.
So you could say that, when it comes to the former USSR and its adherence to non-proliferation, arms control and disarmament conventions, there are some legitimate trust issues.
 
Soviet-era fermenters in Building 221 at Stepnogorsk, Kazak SSR.  Fool me once, shame on you.  Fool me twice...

I guess the final take-away from this is that when it comes to trying to figure out what a potential enemy might be able to do in the near future, one of the best guides is knowing what they've done to you in the near past.  If nothing else, the existence of things like the Vought SLAM and the Polyus Space Battle Station should give us a smidgeon of perspective on some of the prerequisites and challenges involved in creating massive and potentially threatening items of military hardware.  In other words, if we want to figure out whether somebody might put an orbital battle station in Low Earth Orbit and use it to dazzle or destroy our satellites or FOB a nuke onto one of our cities, the first thing we should do is make a list of folks who (a) can build space stations, (b) have a heavy-lift rocket capability, and (c) don't like us.  The intersection in that Venn diagram is where we ought to start looking. 
And if the intersection is empty, maybe we shouldn't waste our time making up non-existant things to fill it.
Anyway, if anyone wants to read Lantratov's article and feels like slogging through 28 pages of "Google-translated" grammar, just let me know.  He gives all the details about cannons, targets, gas generators, and mentions that the black finish on the vehicle was to help maintain working temperature by absorbing solar energy.  It's a cornucopia of awesome, and by the time you're finished reading it you'll be muttering "Commence primary ignition!" under your breath.
Cheers - and may the farce be with you!

//Don//

Notes
A) The paper is available from the DRDC online archive.
B) http://www.buran-energia.com/polious/polious-desc.php
C) http://www.unoosa.org/oosa/SpaceLaw/outerspt.html.  The OST also prohibits laying claim to celestial terrain. 

Thursday, November 1, 2012

19 January 2012 – Going nuclear: Models vs. History

“I’m sure that in 1985 plutonium is available in every corner drugstore, but in 1955 it’s a little hard to come by!” - Dr. Emmet L. Brown

Colleagues,

With Iran’s accelerating nuclear activities (and the periodic unfortunate demise of certain of its scientists) consuming all of our attention, a question of an historical bent seems pertinent:  Just how long does it take to build an atomic bomb?

It’s not an idle query, because there are no hard and fast rules.  Every historical case is unique.  The US Manhattan Project, for example, was launched in 1942 and achieved its first nuclear detonation on 16 July 1945, a delay of only three years.  While a great deal of the elementary physics of nuclear explosives had already been set out (including, in some cases, by scientists who later participated in the Project), the fact that two separate viable bomb designs (gun-type, used in the Little Boy weapon dropped on Hiroshima, and implosion-type, used in the Fat Man design that was tested at Alamogordo and subsequently dropped on Nagasaki), and more importantly two separate production processes for weapons-grade fissile material (highly enriched uranium for the gun-type weapons, and plutonium for the implosion weapons) were arrived at in only three years was a feat of defence-focussed R&D that wouldn’t be repeated until the Apollo Program.

(A note on weapon design.  Gun-type weapons function by slamming two sub-critical masses of fissile material together from opposite ends of a tube.  The speed of assembly is limited by the expansion of the combustion products for the propellant used, and runs at several hundred metres per second. Conventional propellant can create velocities of 500-800 metres per second. In an implosion type weapon, a sphere of fissile material is compressed by the controlled explosion of an outer shell of HE.  HE explodes at a speed of 7000-9000 metres per second, depending on the explosive compound (TNT is at the low end, with an explosive velocity of 6900 m/s, while Octol, which is a mix of 75% HMX and 25% TNT, is at the high end, around 8900 m/s.  Speed of assembly for an implosion type weapon is therefore in the range of tens of thousands of metres per second.  Why this is important will be explained later.)

The US experience therefore serves as the benchmark.  All subsequent nuclear weapons programs benefitted from the success of the Manhattan Project, if only from the knowledge that building a nuclear explosive was possible (something that the Manhattan Project scientists couldn’t confirm empirically until the Trinity test).  More direct assistance was available in some cases; the Soviet atomic program, for example, benefitted from espionage by communist agents in the employ of the US government, while Pakistan’s bomb designs were provided by China.  Still, for the sake of historical comparison, it’s worth tracking the progress of nuclear weapons development by other states, if only to demonstrate the extent to which they differ. 

Progress rates of nuclear weapon programs*
Years
 
Program Start
Fission wpn test
Fusion wpn test
∆to fission
∆to fusion
USA
1942
1945
1952
3
10
USSR
1942
1949
1953
7
11
UK
1946
1952
1957
6
11
FR
1956
1960
1968
4
12
PRC
1958
1964
1967
6
9
India
1967
1974
1998
7
31
Pakistan
1972
1998
-
26
-
DPRK
1956
2006
-
50
-

With the exception of a few outliers, though, the timelines don’t really differ all that much.  In fact, with only two exceptions the average time from program start to achieving a fission explosion seems to vary from 3 to 7 years, with the mode being 6.5 years; while the average time from program start to achieving a fusion (as opposed to simply a boosted fission) explosion seems to vary from 9 to 12 years, with the mode being 11 years.
Of course, those of us looking backward benefit from the existence of historical data points.  And of course there’s no guarantee that the next country to “go nuclear” will necessarily follow historical patterns; every case is different.  Some countries developed nuclear weapons under wartime pressures, while others did not; some had outside assistance, while others went it alone; and one - the US - pursued the project without knowing whether a nuclear weapon was even possible (or, on the other end of the scale, whether it would overperform, and end up setting the atmosphere on fire or destroying the world).  It’s important not to underestimate the value of knowing that something can be done before you set out to try and do it yourself.   It’s also important to bear in mind that at least one of the above countries - Pakistan - likely possessed a nuclear weapon long before testing it.
All of which brings me to the subject of this discussion, which was the attempt by the US Government 46 years ago to try and guesstimate how long it would take for the “next” country to develop a nuclear weapon. 
In May of 1964, the Lawrence Radiation Laboratory at the University of California Livermore (now known as Lawrence Livermore Labs) launched a highly classified, very small project.  Dubbed the “Nth Country Experiment”, the project brought together three post-graduate students, none of whom had any expertise in or specialized knowledge of nuclear weapons, and tasked them to design a workable nuclear explosive device.  The three participants were:

·         David A. Dobson, 27, Ph.D. (Physics, Berkley, 1964) - experimental atomic physics

·         David N. Pipkorn, 28, Ph.D. (Physics, University of Illinois, 1964) - experimental solid state physics

·         Robert W. Seldon, 28, Ph.D. (Physics, University of Wisconsin, 1964) - low temperature physics

Note that all were newly-graduated doctoral candidates.  The experiment was designed to simulate the challenges facing a putative “Nth Country”, one that had access to qualified academic personnel, but no outside assistance.  They were to work entirely from unclassified sources.  The trio were given a single point of contact at LRL - a physicist, A.J. Hudgins - and had to go through him for all information requests.  All communications were conducted in writing to minimize the chance of accidentally passing any helpful information to the team.  Hudgins, using the resources of the weapons designers at LRL and other Department of Energy facilities, took the questions, and - simulating the testing process that would be available to a real team of weapon designers - staffed them out to expert groups to develop answers.  In this way, the trio could propose design and fabrication features for a weapon, and subsequently receive “test data” (derived either from actual previous US nuclear weapon tests, or from simulations of how the proposed material designs might work) to help guide them in their work.
Based on what they were able to learn from unclassified sources (not a great deal, compared to what is available today), they made a number of interesting assumptions about how they should proceed.  I use the word “interesting” because they departed somewhat from their fields and took into consideration economic and political issues in addition to questions of pure physics.  For example, they dismissed U-233 as a fissile material because the cost of building a thorium breeder reactor to produce the element was deemed “prohibitive”.  They established that it would cost about the same to produce U-235 or Pu-239; but when they questioned “Nth Country Treasury Department”, they were informed that the country had the resources to produce one or the other, but not both.  Interestingly, they weighted Pu-239 higher, because it is isolated from uranium reactor waste (whereas U-235 is produced by enriching natural uranium).  This meant that building plutonium-fuelled bombs had economic advantages because it required the “Nth Country” to invest in nuclear reactor technology rather than simply in uranium enrichment technology.
The two other considerations they looked at were physics, and weapon design.  From a physics standpoint, plutonium has both a lower critical mass (meaning less fissile material would be required per bomb) and higher compressibility, which makes it easier than U-235 to use in an implosion type weapon. But plutonium cannot be produced without Pu-240 contamination, which has a high neutron background and a high spontaneous fission rate, making it impossible to use in gun-type weapons, because given their slow assembly speed, the high neutron flux would initiate fission before the core was assembled, causing a premature explosion and a poor yield (a “fizzle”).  U-235, on the other hand, has a low neutron background and a low spontaneous fission rate, meaning that it could be used in a gun-type weapon, which is by far the easier type of design to develop.
According to the trio,

So there was a certain amount of scientific hubris involved in the selection process - which I suppose means that the trio were behaving like normal scientists.  In any event, by December 1964, the three ersatz weaponeers had settled on a plutonium-based implosion type weapon.
The trio attacked the problem in three phases.  Phase I was achieving an understanding of the basic concepts and design considerations required to begin the design process.  Phase II extended the basic physics of the design problem through quantitative neutronics calculations looking at compression characteristics of the materials in question, the design of converging explosive lenses, and the development or selection of detonators and a neutron initiator (an “initiator” provides an initial burst of neutrons to kick-start a fission chain reaction).  The second phase also looked at optimizing the mass of the plutonium core, and establishing the required thickness of the tamper (a metallic layer outside the core that serves both as a solid mass to provide the compressive impulse when struck by the explosive shock wave, and as a neutron reflector to intensify the building neutron flux in the compressed core).  Phase III of the project extended Phase II into final calculations of the implosion physics and the “iterative fission expansion” (i.e., the production of sufficient neutrons at the correct rate to sustain and multiply the fission reaction).  Once these calculations were complete, the bomb design would be “proved” to the maximum theoretical extent possible short of an actual build-and-test.
The trio submitted their design in September 1966.  The final report was submitted in December of that year and was assessed by experienced weapon designers at LRL and elsewhere.  Each of the elements of the design - the core, the tamper, the initiator, the explosives, the detonators, and all of the physics calculations - was individually critiqued.  The final report, which was published in March of 1967, was classified SECRET (ATOMIC WEAPON CATEGORY SIGMA 1), and the version which was released 30 years later in 1995 is so heavily redacted that it does not show whether, in the opinion of the assessors, the design would have worked or not.  The physicists who critiqued the design disagreed with some of the numbers and calculations in the trio’s report, and opined that the designers offered very little firm information about the criticality of the proposed system; they state that “confidence in the expected yield is unwarranted.”  This was not a crushing comment; the US nuclear testing program experienced many extreme variances between expected and actual yields, ranging from numerous complete “fizzles” that achieved no criticality, to the infamous Castle Bravo test shot on 1 March1954, which was expected to produce a yield of 4-6 Mt, but which actually produced a yield of 15 Mt, completely obliterating Bikini Atoll and resulting in a 280-mile fallout plume that contaminated the Marshall Islands and the crew of a Japanese fishing vessel. Sometimes you don't know what you don't know until you "go empirical", and find out the hard way.
One of the interesting things about the report of the Nth Country Experiment is that while the redactors severed anything that might assist an actual Nth Country in building a bomb, they left in a good many very interesting observations made by the project trio and by the experts that assessed their work.  The trio, for example, rejected a priori any comparison between their work and the work at Los Alamos by the Manhattan Project scientists, noting that that prior group contained “some of the world’s outstanding physicists”, and acknowledging the “motivational climate in which they worked.”  The trio, by contrast “had the advantage of knowing that a bomb could be built”.  They also acknowledged the importance of having access to a library containing “a large quantity of literature on shock waves, explosives, nuclear physics and reactor technology” that had been published since 1945.  They noted that the project rules slowed them down somewhat; they spent “a good deal of time preparing requests which presented enough information about our understanding of what was being requested so that a suitable reply could be obtained”; such procedures would not necessarily obtain if a real Nth Country was racing to build a bomb.  There were no artificial firewalls or stovepipes between the physicists, engineers and technicians working at Los Alamos.
They also noted that they could have designed a U-235-based gun type bomb, and that had they done so, they would have been able to submit a working design much earlier.  They also made two very interesting observations about thermonuclear weapons, stating first that while they believed that their implosion weapon would be credible without a test, they could see no way of designing a thermonuclear weapon without testing.  In that context, they made the following observation:

That report was submitted on 14 December 1966.  Exactly six months later, on 17 June 1967, China tested its first thermonuclear weapon, a 3.3 Mt radiation implosion (Teller-Ulam) style device, at Lop Nor.  Obviously the trio knew what they were talking about.
The assessment team also made a number of very interesting observations about the assumptions made by the trio in designing their approach to the experiment:
In other words, an Nth Country might be less interested in long-term economic benefits and challenging scientific problems than getting their hands on a workable bomb NOW.  Such a country might opt for uranium enrichment and a simple, reliable gun-type weapon over building a plutonium production complex and designing a complicated implosion type weapon.
It would certainly explain why, for example, a country with immense oil and gas reserves might be building an enormous uranium enrichment complex (<cough> IRAN <cough>). Hint: it's not for nuclear power plants.
Would a new bomb project work out the same way today?  A lot of things are different from 1966.  There’s a lot more information out there about nuclear weapons design, it’s a lot easier to find thanks to the Innerwebz; and it’s an AWFUL lot easier to do the kinds of calculations necessary to design explosives, cores and shock waves.  One of the anecdotes recounted by Robert Seldon during an interview for the final report details just how much computing technology changed from 1945 to 1965:

An average laptop today has orders of magnitude more computing power than the LRL mainframe did in 1965, and that mainframe was orders of magnitude more powerful than "a room full of girls with desk-calculators".  What took months of data manipulation for the Trinity scientists and weeks of programming for the Nth Country trio would take at most hours for a modern computing setup. Maybe seconds.
So what’s the point of all of this?  Well, I find it interesting that the Nth Country trio managed to get from nothing to what was likely a workable bomb design in about two and a half years of desultory effort (only one of the members was full-time; the others were part-time), all while working from unclassified sources.  That matches pretty closely to the low end of the “delta to fission” timeline that history demonstrates seems to be the average to get to a working bomb.  If you factor in having to build a reactor and produce and refine plutonium from the reactor waste (which admittedly would probably be done concurrently to the bomb design effort), you might add another year or two to that, still falling comfortably into the mid-range of the average time it takes for a country to go from nothing to its first fission test.  So here we have a case where the output of an experimental model seems to line up fairly well with historical experience.
Suppose we apply that model and experience to Iran...what do we get?  Well, it’s a little hard to nail down the beginning of Iran’s nuclear weapons program, as they’ve had a reactor program for quite some time.  The existence of concealed uranium enrichment facilities was revealed in 2002, launching the ongoing IAEA investigation process and leading to seven successive UNSC resolutions demanding cessation of enrichment and imposing sanctions.  Iran has since “doubled down”, building more enrichment capacity and declaring itself a “nuclear state” in 2010.  The point is that we are at the very least well past the decade mark in Iran’s quest for nuclear weapons.  Only North Korea took longer to go from “mission” to “fission” - and Iran isn’t North Korea.  We won’t be able to put Iran on the chart until they actually detonate a nuclear weapon - but if history and the Nth Country Experiment are any guide, statistically speaking there’s a pretty solid chance that they’ve already got one.
But as I said above - “of course there’s no guarantee that the next country to 'go nuclear' will necessarily follow historical patterns; every case is different.”  Some countries - like South Africa, Brazil, and Argentina - stop short of testing.  Others might be stopped short of testing.  I hate to say “we’ll have to wait and see what happens”, but everything, in one way or another, is an experiment, whether it’s leaving 3 guys alone in a room for a couple of years and waiting to see what they come up with...or leaving a bunch of folks like Khomeini and Ahmadinejad alone in a resource-rich country for three decades, and waiting to see what they come up with.
Some experiments go well.  Some don’t.  I guess we’ll have to wait and see how this one goes.
While we're waiting, if you'd like to read the (expurgated) summary report of the Nth Country Experiment, it's available here:
Cheers,
//Don//

Notes

A) I left Israel off the list because the alleged start date for their nuclear weapon program is unconfirmed, and there has been no confirmed test.  Although if that data were entered, it would be a start date in the “late 1950s” with a first weapon built in the “late 1960s”, and a possible test (in conjunction with South Africa) in 1979.  This would give a “delta to fission” of about 20 years.  Deployment-before-testing is historically unusual, but not surprising in an undeclared nuclear power that likely received outside assistance with, and therefore had high confidence in, its bomb design.  Pakistan almost certainly fits this mould as well; it received bomb design assistance from China, and almost certainly had a deployed nuclear weapon long before conducting its first test in 1998 in response to India’s wave of nuclear tests.

Thursday, October 18, 2012

11 January 2011 – The impossibility of data management

Colleagues,

Empirical science has four steps: observation, hypothesis, experimentation and synthesis.  Two of those - observation, which requires noting a previously unexplained phenomenon, and experimentation, which is designed to produce evidence - are based, respectively, on collecting and generating data for further analysis.  Data is the bedrock of the scientific method, because it is only through data that established, often cherished, assumptions about how the world works may legitimately be challenged.  So you’d think there couldn’t be any such thing as ‘too much’ data, right?

“Wrong,” says David Weinberger.  In a new book with the wonderfully expressive title Too Big to Know: Rethinking Knowledge Now That the Facts Aren’t the Facts, Experts are Everywhere, and the Smartest Person in the Room is the Room, Weinberger argues that our ability to generate data is outstripping not only our ability to organize it in such a way that we can draw useful conclusions from it, but even our cognitive ability to grasp the complexities of the phenomena we are trying to understand.

This isn’t a new phenomenon.  As Weinberger notes, in 1963 - right around the same time that Edward Lorenz formulated chaos theory to explain the inherent impossibility of predicting the long-term behaviour of non-linear systems like weather - Bernard Forscher of the Mayo Clinic published a letter in Science entitled “Chaos in the Brickyard”, in which he complained that scientists were generating - of all things - too many facts.  According to Weinberger,

...the letter warned that the new generation of scientists was too busy churning out bricks — facts — without regard to how they go together. Brickmaking, Forscher feared, had become an end in itself. “And so it happened that the land became flooded with bricks. … It became difficult to find the proper bricks for a task because one had to hunt among so many. … It became difficult to complete a useful edifice because, as soon as the foundations were discernible, they were buried under an avalanche of random bricks.” [Note A]

The situation today, Weinberger argues, is astronomically - and I use the word “astronomically” quite deliberately, in the sense of “several orders of magnitude” - worse than it has ever been.  In an article introducing his book, he puts the problem thus:

There are three basic reasons scientific data has increased to the point that the brickyard metaphor now looks 19th century. First, the economics of deletion have changed. We used to throw out most of the photos we took with our pathetic old film cameras because, even though they were far more expensive to create than today’s digital images, photo albums were expensive, took up space, and required us to invest considerable time in deciding which photos would make the cut. Now, it’s often less expensive to store them all on our hard drive (or at some website) than it is to weed through them.

Second, the economics of sharing have changed. The Library of Congress has tens of millions of items in storage because physics makes it hard to display and preserve, much less to share, physical objects. The Internet makes it far easier to share what’s in our digital basements. When the datasets are so large that they become unwieldy even for the Internet, innovators are spurred to invent new forms of sharing.  The ability to access and share over the Net further enhances the new economics of deletion; data that otherwise would not have been worth storing have new potential value because people can find and share them.

Third, computers have become exponentially smarter. John Wilbanks, vice president for Science at Creative Commons (formerly called Science Commons), notes that “[i]t used to take a year to map a gene. Now you can do thirty thousand on your desktop computer in a day. [Note A]

The result, Weinberger argues, is actually worse than Forscher predicted.  We are not merely awash in “bricks/facts” and suffering from a severe shortage of “theory-edifices” to organize them with; the profusion of data has revealed to us systems of such massive intricacy and interdependence that we are incapable of visualizing, let alone formulating, comprehensive theories to reduce them to manageable - by which is meant, predictable - rules of behaviour.  Scientists facing “data galaxies” are being forced down one of two paths.  The first path - reductionism - attempts to derive overarching, general principles that seem to work well enough to account for the bulk of the data.  Historically, searching for “universals” amid the vast sea of “particulars” has been the preferred approach of empirical science, largely because there tend to be many fewer universals than there are particulars in the physical world, and also because if you know the universals - for example, Newton’s laws of motion and the fact that gravitational attraction between two objects varies inversely as the cube of the distance separating them - then you can often deduce the particulars, for example, where you should aim your Saturn V rocket in order to ensure that the command and service module achieves Lunar orbit instead of ending up headed for the heliopause.

The second path - modelling - involves the construction of tunable mathematical models that can be tweaked to produce outputs that mimic, as closely as possible, observational data without attempting to derive an overarching theory of how the system that produced the data actually functions.  This has been the preferred approach for dealing with complex phenomena that do not easily lend themselves to reduction to “universals”.  When it comes to complex systems, however, both paths exhibit crippling flaws.  Overarching theories that explain some data, but not all of it, can help us to approach a solution, but they cannot produce “settled science” because unexplained data are by definition the Achilles Heel of any scientific theory.  Meanwhile, modelling, even if it can come close to reproducing observed data, cannot replace observed data, and is never more than a simulation - often a grossly inaccurate one - of how the real world works, because if we cannot visualize all of the complexities and interdependencies of a given problem set, we certainly cannot design mathematical formulae to simulate them.

As if these two unacceptable paths were not bad enough, perhaps the most alarming deduction that Weinberger draws from his analysis is that these data-driven trends are forcing us towards a “new way of knowing” that is, from a human perspective, almost entirely “virtual.”  According to Weinberger, only computers can generate the vast quantities of data necessary to investigate a given phenomenon; only computers have the capacity to organize and store so much data; and only computers can perform the unthinkable number of calculations necessary to process the data and create modelled outputs.  Our role, such as it is, has been to create the mathematical models for the computers - but even this last redoubt of human involvement is collapsing as we become increasingly incapable of visualizing the scope and interrelationships of the problems we are trying to solve.  In other words, the future of research into complex interdependent phenomena is gradually departing the human domain, simply because we lack the cognitive wherewithal needed to cope with it.

Does this mean that scientific inquiry is doomed to leave the human sphere entirely?  Or that it’s destined to grind to a halt unless we can come up with an AI that mimics human cognition to the point of being able to visualize and craft investigative solutions to huge, complex problems?  I certainly don’t dispute that science has developed the ability to drown itself in data; but there are ways of dealing with preposterous quantities of information.  As I believe I’ve pointed out before, historians are accustomed to being drowned in data.  From the point of view of the science of historiography, this is not a new problem.  Take, for example, a relatively straightforward historical event - the Battle of Waterloo.  Working from basic numbers, Napoleon had about 72,000 troops, and the Allies under Wellington had about 118,000.  Reducing the affair to nothing more than a series of iterative diarchic interactions (which I am the first to admit is a wholly ludicrous proposition, but which frankly is no more ridiculously inappropriate than some of the assumptions made in climate modelling - for example, the assumption that clouds warm the Earth, when observed data suggest that they cool it) suggests that there were about 8.5 billion potential diarchic interactions in the first iteration alone.  And that’s only the individuals.  Nothing is too insignificant to be eliminated from your model, and each increase in the fidelity of the data you input ought to help refine the accuracy of your output (unless you’re trying to model a non-linear system, in which case the fidelity of your input doesn’t matter because inherent instabilities will quickly overwhelm the system (see “Nonlinearity andthe indispensability of data”, 15 June 2011)).  In the quest for greater fidelity/realism, you would need to model the characteristics and behaviour not just of each individual but also of their weapons, their clothing, their boots or shoes, their health and physical condition, their horses, their guns, their limbers, their ammunition, the terrain, the obstacles, the weather, the psychological vagaries of individual soldiers and commanders...how many details are we talking about here?  Are we getting to the level of a “non-visualizable” problem yet?

Is it even possible to model something this complex?  Well, it’s sort of already been done.  I’m sure many of you have seen The Lord of the Rings: The Two Towers.  The final battle at Helm’s Deep comprised hundreds of Rohirrim and Elves, and ten thousand Uruk-Hai - and yet there were no more than a hundred live actors in any of the shots.  The final digital effects were created by Weta Digital using a programme called “Massive”.  According to Stephen Regelous, the chap who programmed the battle sequences, he didn’t really “program” them at all, or at least, not in the sense of crafting specific movements for every digital effect in the scenes.  That would have been an impossibly daunting task, given the number of individual digital actors involved.

Instead, he made the digital actors into people.  “The most important thing about making realistic crowds”, Regelous explains, “is making realistic individuals.”  To do that, the programme creates “agents”, each of which is in essence an individual with individual characteristics, traits, and most important of all, volition:

In Massive, agents’ brains - which look like intricate flow charts - define how they see and hear, how fast they run and how slowly they die. For the films, stunt actors’ movements were recorded in the studio to enable the agents to wield weapons realistically, duck to avoid a sword, charge an enemy and fall off tower walls, flailing.

Like real people, agents’ body types, clothing and the weather influence their capabilities. Agents aren’t robots, though. Each makes subtle responses to its surroundings with fuzzy logic rather than yes-no, on-off decisions. And every agent has thousands of brain nodes, such as their combat setting, which has rules for their level of aggression. When an animator places agents into a simulation, they are released to do what they will. It’s not crowd control, but anarchy. Each agent makes decisions from its point of view. [Note B]

In other words, outcomes aren’t predetermined; the Agents are designed with a range of options built into their makeup, and a degree of choice about what to do in response to given stimuli.  Kind of like people.  While it’s possible to predict likely responses to certain stimuli, it’s not possible to be certain what a given Agent will do in response to a given event.  “It’s possible to rig fights, but it hasn’t been done,” Regelous says. “In the first test fight we had 1,000 silver guys and 1,000 golden guys. We set off the simulation, and in the distance you could see several guys running for the hills.”

If you happen to own the full-up Uber-GeekPathetic Basement-Dwelling Fan-Boy LOTR collection (I admit nothing!), you can watch the “Making Of” DVDs for Two Towers, and listen to a much more in-depth explanation of how chaotic, complex and unpredictable the behaviour of the Massive-generated battle sequences were.  The programmers ran the Helm’s Deep sequence many, many times, using the same starting conditions, and always getting different results.  If that sounds familiar, it’s because it’s exactly what Lorenz described as the behaviour of a non-linear system.  It’s chaos in a nutshell. 

According to the DVD explanation, the results of individual volition were potentially so unpredictable that the Agents’ artificial intelligence needed a little bit of tweaking to ensure that the battle scenes unfolded more or less in line with the script.  Early on, for example, the designers had given each Agent a very small probability of panicking and fleeing the battle, along with a slight increase to that probability if a neighbouring agent went down hard, and a slightly greater probability if a neighbouring agent panicked and fled.  Reasonable, right?  We all know that panic on the battlefield is contagious.  The problem is that, depending on how the traits of the Agents were programmed, it could be too contagious.  In one of the simulation runs for the battle, one of the Uruk-Hai Agents near the front lines apparently panicked and fled at exactly the same time as a couple of nearby Agents were shot and killed.  This sparked a massive, rapidly propagating wave of panic that resulted in Saruman’s elite, genetically-engineered army dropping their weapons and heading for the hills.  I’m sure King Theoden, Aragorn, and hundreds of unnamed horse-vikings and elf-archers would’ve preferred it if Jackson had used that particular model outcome for the film, but it probably wouldn’t have leant itself to dramatic tension. And it would've been something of a disappointement when Gandalf, Eomer and the Rohirrim showed up as dawn broke across the Riddermark on the fifth day, only to discover that there was no one left for them to fight because Uruk Spearman #9551 had gone wobbly a couple of hours before.

What’s the point of all this?  Well, the link between Forscher’s complaint about the profusion of data-bricks and Weinberger’s conclusion that computers are taking over the process of generating, storing, and figuring out what to make of data is obvious.  The problem of deriving “universals” from the colossal mass of “particulars” that make up modern scientific (and historical) inquiry ought to be obvious, too, and it’s demonstrated by one of the key weaknesses of history: experimental repeatability.  Steve Regelous could re-run the Battle of Helm’s Deep as many times as he liked until he got the result that Peter Jackson wanted - but that’s fiction, and when you’re writing fiction you can do whatever you like because you’re not tied to any objective standard other than some degree of plausibility (which in turn depends on the expectations, experience and gullibility of your audience).  But we can’t re-run the Battle of Waterloo, changing one variable here or there to see what might have happened differently, because there’s no way to account for all possible variables, there’s no way to find out whether some seemingly insignificant variable might have been overwhelmingly important (butterfly wings, or “for want of a nail”, and all that), and finally there’s no way to scientifically validate model outputs other than to compare them to observed data, because historical events are one-time things.

What we can do, though, is try to develop rules that help us winnow the “universals” from the chaff that makes up most of history.  There were 190,000 “Agents” at Waterloo - but do we really need to know everything about them, from their shoe size to how many were suffering from dysentery on the big day?  Do we need all of the details that had to be programmed into Weta’s “Massive” Agents?  Or are there some general principles that we can use to guide our understanding of history so that we can pull out what’s important from the gigantic heap of what isn’t?

This is where a good reading - or hopefully re-reading - of E.H. Carr’s What is History? comes in handy.  In Chapter One, “The Historian and His Facts”, Carr disputes the ages-old adage that “the facts speak for themselves”, arguing instead that the facts speak only when the historian calls on them.  Figuring out which facts to call on is the historian’s métier.  Separating the gold - the “significant” as opposed to the “accidental” facts of a given phenomenon - from the dross of historical data is the historian’s challenge, and Carr’s criteria for judgement of what is “gold” is generalizability.  The key word here, of course, is “judgement” - informed judgement as a function of human cognition.  This is something that can’t be done by computers. 
 
Not yet, anyway. [Notes C, D] 

So for the time being, at least, there’s still a need for a meat plug somewhere in the analysis chain, if only to provide the informed judgement that our eventual silicon replacements haven’t quite learned to mimic.  That’s something of a relief.

Cheers,

//Don// (Meat plug)

Notes:


C) Historians looking for a lesson in humility need only read Heinlein’s The Moon is a Harsh Mistress, in which a computer that accidentally becomes artificially intelligent finds itself having to run a Lunar uprising - and in order to design the best possible plan for doing so, reads every published history book in a matter of minutes, analyzes them, and then not only plots a revolution from soup to nuts, but actually calculates the odds of victory, and recalculates them periodically in response to changing events.  Now that’s what I call “future security analysis.”  If only.

D) Some computer programmes are getting pretty good at matching human cognition.  Fortunately, we still hold an edge in important areas.  As long as we can still beat our electronic overlords at “Rock-Paper-Scissors”, we might, as the following chart from the genius webcartoon xkcd.com suggests, be able to hold the Singularity off for a little longer.