Explosives Found in

World Trade Center Dust Scientists Discover Both Residues

And Unignited Fragments

Of Nano-Engineered Thermitic Pyrotechnics

In Debris From the Twin Towers by

Jim Hoffman

Version 1.00, April 3, 2009

Version 1.01, April 9, 2009

Version 1.02, October 23, 2009

Version 1.03, December 7, 2009

Introduction

The scientific paper Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe conclusively shows the presence of unignited aluminothermic explosives in dust samples from the Twin Towers, whose chemical signature matches previously documented aluminothermic residues found in the same dust samples. The present review of the paper and related research is intended to summarize those findings for the non-technical reader. To that end, I first provide a short introduction to the subject of aluminothermic explosives, then outline the methods and results of analysis of the dust samples, and finally explore the significance of these findings.

Contents

Aluminothermics 101

Aluminothermic reactions are a class of energy-releasing oxidation-reduction chemical reactions in which elemental aluminum reduces a compound, typically by stealing the oxygen from a metal oxide. Aluminothermics range from low-tech preparations that take seconds to react and therefore release nearly all their energy as heat and light, to advanced engineered materials with accelerated reaction rates that yield explosive powers similar to conventional high explosives.

Backers of the official account of 9/11, including NIST officials, have dismissed evidence that aluminothermics were used to destroy the World Trade Center skyscrapers, claiming that thermite's slow reaction rate makes it an unsuitable tool for demolishing buildings. Despite repeated requests by scientists and researchers to address the potential role of advanced aluminothermic composites with high explosive power, officials have refused to acknowledge such materials.

Composition

2 Al + Fe 2 O 3 → Al 2 O 3 + 2 Fe

The most familiar aluminothermic material is thermite, a mixture of a powdered metallic fuel such as aluminum, and a powdered oxide of another metal such as iron or copper. The thermite reaction involves the transfer of oxygen from the oxidizer (metal oxide) to the fuel (metal).

Because oxygen atoms bind more tightly to aluminum atoms than to iron or copper atoms, the reaction releases large amounts of energy and is described as highly exothermic. Whereas primitive thermite preparations release most of their energy as heat, modern preparations, such as found in munitions employed by the US military in recent decades, produce a targeted mix of heat and pressure through an accelerated but controlled reaction rate and the addition of pressure-generating compounds such as hydrocarbons.

Reaction Rate

The reaction rate of a thermitic material determines how quickly its aluminum atoms find oxidizer molecules to react with, and therefore how quickly the energy is released. Whereas the energy density of an explosive is determined by its chemistry, its power density is determined by its reaction rate, which, in the case of a thermitic material, is determined by its physical characteristics. Specifically, the reaction rate increases with the fineness of the metal and oxide powders and the uniformity with which they are mixed.

Because the particle sizes of the reactants must be very small to attain rapid reaction rates, such thermites are often referred to as nano-thermites. Such nano- or "super-thermites" typically have particle diameters on the order of a few hundred nanometers, requiring their synthesis by special methods. The reaction rate in turn determines the destructive character of the material. Whereas a cup of conventional thermite will melt a hole clear through a car's engine block, the same quantity of a nano-thermite composite explosive will blow the car apart.

Nano-thermite composite explosives typically embed the metal and oxide particles within a matrix containing compounds of carbon, oxygen, hydrogen, and silicon. These additional elements generate high gas pressures upon exposure to the thermite reaction, which may be instrumental in imparting high-explosive properties to such materials.

Energy Density and Power Density

material energy density by mass:

MJ/KG by volume:

MJ/L aluminothermic incendiaries Thermite

(Al + Fe 2 O 3 ) 4.13 18.40 Copper Thermite

(Al + CuO) 4.00 20.90 nitro-aromatic explosives TNT

(Trinitrotoluene) 4.61 6.92

In terms of energy density, thermite is roughly comparable to TNT, packing slightly less energy per unit of mass but about three times as much energy per unit of volume. In terms of power density, thermitic preparations range across a wide spectrum, whose upper end appears to be comparable to conventional high explosives. [1] [2]

Because thermites have historically had much lower power densities than conventional high explosives, they are classified as incendiaries rather than explosives -- a classification that has been exploited to conceal the use of aluminothermics in the World Trade Center attack. Despite the fact that high-tech aluminothermics have existed and been used by the military since the mid-1990s or earlier, methods of identifying explosive residues at crime scenes are frequently limited to analysis of nitro-aromatic explosives. [3]

Energetic Nanocomposites

The term 'nano-thermite' applied to the unignited thermitic material discovered in World Trade Center dust is potentially misleading because it doesn't capture the complexity and sophistication of this material or its known analogs. Perhaps a better term is energetic nanocomposites, a class of materials that has been used by the military for some time in applications spanning propellants, armor-piercing munitions, and reactive armor. In their diverse roles, energetic nanocomposites fulfill a range of requirements including: "high density, good mechanical properties, low sensitiveness, good stability, low cost, ease of manufacturing, and environmental acceptability." [4] To achieve these requirements, scientists developing advanced aluminothermic materials have learned to embed the fine powders in a carbon- and silicon-rich matrix. Kevin Ryan explains:

The mixing [of ultra fine grain (UFG) aluminum and UFG metal oxides] is accomplished by adding these reactants to a liquid solution where they form what are called "sols", and then adding a gelling agent that captures these tiny reactive combinations in their intimately mixed state (LLNL 2000). The resulting "sol-gel" is then dried to form a porous reactive material that can be ignited in a number of ways. 5]

Energetic materials such as aluminothermic sol-gels have been an active area of research in the US national labs since the mid-1990s or earlier, including under the auspices of NIST itself -- a fact documented by Kevin Ryan in his extensively footnoted article The Top Ten Connections Between NIST and Nano-Thermites. Also called "metastable intermolecular composites", "nano-structured energetic materials", or just "nanoenergetics", these materials have been the subject of numerous conferences, research papers, and patents in the past two decades. [6] [7] [8] [9] [10] [11] It's also not difficult to find recent published papers on methods of reliably igniting such materials with minute low-power devices described as MEMS (microelectromechanical systems) and manufactured much like conventional integrated circuits. [12] [13] [14] [15] [16] [17] [18] It requires little imagination to grasp how such techniques could be exploited to implement a covert, all-wireless controlled demolition.

Aluminothermics at the WTC

The discovery of unexploded super-thermite in the WTC dust augments a large body of evidence pointing to the use of aluminothermic materials in the destruction of the skyscrapers. The present review looks only at the evidence of explosives found in the dust and debris expelled from the Twin Towers.

Even before WTC dust was subjected to the kind of microscopic scrutiny described in Active Thermitic Material Discovered , several features of the dust analysis published by the USGS pointed to the use of aluminothermics. For example, the USGS data shows high levels of barium -- a fact that is difficult to explain, barring pyrotechnics. The high levels of iron and aluminum in the dust -- each ranging from 1.3 to 4.1 percent of the dust samples by weight -- also appears anomalous, although prosaic sources of the metals can be imagined.

Aluminothermic Residues: Iron-Rich Spheroids

Micro-spheroidal particles in WTC dust consisting mostly of iron were documented in at least two scientific reports by 2005: a compilation of data by the USGS and a report for the owners of a skyscraper adjacent to the World Trade Center complex that sustained heavy damage in the attack. [19]

Although it may be overlooked, the significance of these nearly microscopic iron-rich droplets is not difficult to grasp. Molten iron is one of the two principal products of the thermite reaction, the other being aluminum oxide, which tends to dissipate as an aerosol. The molten iron condenses and solidifies into particles whose size is a function of the thermite's reaction rate. Fast-acting super-thermites produce tiny droplets that become very nearly spherical due to surface tension.

The inescapable fact is that these spheroidal droplets in the WTC dust look exactly like the products of the combustion of nano-thermite explosives, and their discovery in consistently substantial concentrations in diverse samples of dust from the day of the attack weighs heavily against theories that they were generated by something other than the Twin Towers' destruction. Elemental analysis of these droplets described below would show that they are dead ringers for known aluminothermic residues.

In a 2007 paper, Steven Jones described the importance of the iron-rich microspheres. [21]

As usual, we search for possible prosaic explanations for these metallic spherules in the WTC dust. The most obvious possible source is the melting of large quantities of steel in the buildings followed somehow by formation of tiny droplets of molten steel. As discussed above, however, steel melts at about 1538ºC (2800ºF) – and the temperatures in the buildings were no where near [sic] hot enough to melt steel, and certainly not in large quantities required for the amounts seen in the dust (and pouring out of the South Tower before collapse). Furthermore, we have looked at the chemical compositions of a number of iron-rich spherules as well as that of steel, and the compositions are not the same at all. It should not be surprising, however, as we analyze more spherules to find some that are steel-like in composition, assuming that thermite cutter-charges were in fact used to cut through steel. We should then find both steel- and thermite-residue spherules.



Could these droplets be due to molten aluminum alloy (from the jets) striking rusty steel and/or other office materials to somehow generate the iron-rich spheres? We performed experiments with molten aluminum poured onto rusty steel, then onto crushed gypsum and concrete (on the rusty steel) – and observed no formation of iron-rich droplets at all nor any sign of vigorous chemical reactions.

After addressing arguments that the iron-rich droplets could have been produced by the rubble pile or clean-up operation -- the dust samples were collected too early and were too distant from the site to have been thus contaminated -- Jones makes a rough estimate of the total quantities of reactants involved in the attack based on the fraction of the dust comprising the iron-rich spheres.

One can estimate the implied amount of thermite needed to generate so many iron-rich spheres in the WTC dust. In a sample of 32.1 grams of WTC dust, I observed with the unaided eye two metallic-looking spheres, in addition to the micron-sized spherules collected using a magnet. The mm-size spheres proved to be iron-aluminum rich. The mass of these two larger spheres (0.012g) found in this sample can be used to provide a crude estimate of the fraction of iron-rich spheres in the dust: 0.012g/32.1g = 0.04%. If the mass of the WTC dust was about 30,000 tons, then the iron-rich spherule content would be of the order of ten tons. This is a very rough estimate based on one small sample, and is only provided to give an idea of the amount of thermite-type reactants and products which may be involved here. An investigation well beyond the scope of this paper would look for purchases of aluminum and iron-oxide powders (and sulfur) in multi-ton-quantities prior to 9/11/2001.

A paper published a year earlier than Active Thermitic Material Discovered showed that metal-rich spheroids in WTC dust had iron-to-oxygen ratios indicating abundant elemental iron, such as found in thermite residues. It also pointed out several other features of WTC remains that indicated exposure to temperatures far above what could be produced by fires burning jet fuel and office contents, including: iron-rich and silicate spherules, volatilized lead, a molybdenum spherule, and materials with a "Swiss-cheese appearance". [22] Molybdenum has a very high melting point of 2617ºC.

Unignited Aluminothermics: Bi-Layered Chips

If finding aluminothermic residues in the form of spheroidal micro-droplets was like finding fired bullets at a crime scene, then the discoveries presented in Active Thermitic Material Discovered are like finding the gun loaded with several rounds of unspent ammunition that match the fired bullets.

First described by Steven Jones in late 2007, distinctive chips found in the dust samples had red and gray layers, were weakly attracted to a magnet, and were composed mostly of iron, oxygen, aluminum, silicon, and carbon. Jones and his colleagues subsequently subjected the chips to detailed analysis using scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (XEDS), and differential scanning calorimetry (DSC), and published their results in the Open Chemical Physics Journal.

Provenance of the Samples

The paper's findings are based primarily on the analysis of particles derived from four separate samples of dust generated by the destruction of the Twin Towers, samples whose provenance the paper describes in detail. Each of the samples was collected by a different individual who has described the time, place, and methods of collecting and storing their sample. Each individual collected dust that had settled directly after the fall of one of the Twin Towers, with the one exception, Janette MacKinlay, who collected dust when allowed to re-enter her apartment a week after it was carpeted with shovel-fulls of dust and debris from the South Tower.

Physical Structure of the Chips

Chips having distinctive and similar physical features were found in all four of the dust samples, ranging in length from from about 0.2 to 3 mm. Each chip has stratified layers of two types: a red layer and a lighter gray layer, where each layer is between roughly 10 and 100 microns in thickness. Despite their small size, the chips are readily visible in the samples because of their flat shapes, distinctive color, and layered structure. The chips are tough despite being as thin as eggshells.

Magnification reveals that the gray layers are composed of an opaque homogeneous material, whereas the red layers have small particles embedded in a matrix of slightly translucent material.

At magnification of 50,000 the structure of the two types of particles is clear: small bright particles having a faceted shape and measuring about 100 nm in diameter, and larger particles having a flat and often hexagonal shape and measuring about 1000 nm across and 40 nm thick.

The particles are held in place and in close proximity to each other by the porous matrix. Soaking the chips in methyl ethyl ketone, a solvent that dissolves paint, caused the red layer to swell while remaining intact.

Up to this point, I have reviewed only characteristics of the chips revealed by macro- and micro-scopic visual examination, but already the implications are stunning: the chips are clearly a nano-engineered material with two types of extremely small particles, each highly consistent in shape and size, held in close stable proximity by a durable matrix which is laminated to a hard homogeneous material. The student of energetic materials will appreciate that this description matches exactly that of a super-thermite in which the reactant particles are suspended in a sol-gel matrix applied to a substrate.

Chemical Composition of the Chips

Chemical analysis of the chips relied primarily on performing elemental analysis of the materials and their components using XEDS, and making inferences about the materials' molecular composition based on the distributions of elements in different structures. The paper first examines the gray and red layers, and then zooms in on the components of the red layers.

XEDS spectra of red and gray layers shows a remarkable similarity across the different samples.

Whereas the gray layers contain mostly iron and oxygen, the red layers have abundant aluminum as well, and the three elements are in the ratio approximating that of Fe 2 O 3 + Al thermite. Thus, the red layers could be active thermitic material, depending on their molecular composition. If active, the material will have much of its aluminum in a metallic state, unbound to oxygen or silicon.

The authors show that the aluminum is indeed mostly in a pure metallic form, and that much of the oxygen is bound to the iron. They ultimately show this conclusively through elemental analysis of the components of the red layers: the thin hexagonal plates, faceted grains, and embedding matrix revealed by microscopic inspection.

Performing accurate elemental analysis of the red layer components would require some ingenuity. Because the XEDS machine steers an electron beam over a sample's surface to gather information about its elemental composition, it can be used to generate maps of the abundance of different elements over the surface of the sample. However, the particles in the red layer are slightly smaller than what can be resolved by XEDS.

Nonetheless, considering the XEDS maps in conjunction with the much higher-resolution SEM images of the corresponding portions of the sample makes clear that the faceted grains are abundant in iron and oxygen and the thin plates are abundant in aluminum. Also, although the distribution of particles in the matrix is precisely homogeneous overall, there are local clumps of grains and of plates, and when the electron beam is focused on these clumps the XEDS detector registers higher concentrations of the constituents of iron oxide and of elemental aluminum, respectively.

To obtain more precise measurements of the elemental compositions of the red layer components using XEDS, those components somehow had to be separated, so that the electron beam could be focused entirely on one component at a time. Perhaps the porous matrix could be dissolved, allowing the particles to be separated by centrifuging. Or better -- as the investigators discovered serendipitously in an earlier experiment to see if the chips dissolved in the paint-dissolving solvent methyl ethyl keytone (MEK) -- the matrix could be expanded by a factor of five while leaving the layer intact, allowing in-situ examination. When the chips were soaked in MEK with periodic agitation for 55 hours, the red layers swelled up but remained intact and attached to their respective gray layers, and the thin plates tended to migrate and aggregate. Because of these structural changes produced by the MEK soaking, it was possible to make much more accurate XEDS measurements of the elemental compositions of the red layers' components.

XEDS maps of a soaked red layers show correlations much more clearly than the untreated material. In particular, oxygen is highly correlated, individually, to iron, silicon, and carbon. Aluminum is inversely correlated to the other elements.

Even more striking are the XEDS spectra found by zooming in on areas having high concentrations of particular elements. The three graphs below show the results of focusing the electron beam on areas with: first, high silicon; second, high aluminum; and third, high iron. The area of high silicon is composed almost entirely of silicon and oxygen, the area of high aluminum has aluminum far out of proportion with the other elements, and the area of high iron is rich in oxygen, where the oxygen and iron atoms are in the same 3-to-2 ratio as in the thermite oxidizer Fe 2 O 3 .

The authors draw the obvious conclusions from their elemental analysis of components of the red layers: the aluminum-rich particles are mostly elemental aluminum, with the relatively small quantities of oxygen being accounted for by an oxide layer on the particles' surfaces; the iron-rich particles are primarily oxygen and iron, probably in the form of the oxidizer Fe 2 O 3 which matches the observed 3:2 ratio of oxygen to iron atoms; and the matrix is composed almost entirely of silicon, oxygen, and carbon, where most of the carbon was washed away by the MEK. The matrix also may contain hydrogen, which is not detected by XEDS analysis.

Given the data in Active Thermitic Material Discovered I summarize the composition of the chips as follows:

gray layer : a hard homogeneous ceramic

composition: iron and oxygen

: a hard homogeneous ceramic composition: iron and oxygen red layer : an engineered nano-composite substance, comprising: matrix : a nano-structured semi-transparent porous material

composition: silicon, oxygen, and carbon particles : homogeneously embedded in the matrix and consisting of: thin predominantly hexagonal plates

dimensions: ~40nm thickness, ~1000nm diameter

composition: mostly aluminum, with small amounts of carbon and oxygen rhombic faceted grains

dimensions: ~100nm diameter

composition: mostly iron and oxygen, probably as Fe 2 O 3 , with small amounts of silicon, sulfur, and carbon

: an engineered nano-composite substance, comprising:

Thermal Behavior of the Chips

The structural and chemical analysis of the chips shows that, in every relevant aspect, they fit the description of an engineered thermitic nanocomposite. This prompts the obvious question: do the chips have the thermal characteristics of an explosive aluminothermic material?

Although it might be difficult or impossible to measure the explosive power of the chips, given their minute size, it is possible to measure their exothermic behavior and thereby calculate their energy density using a differential scanning calorimeter (DSC), a device that gradually increases the temperature of a sample and records the amount of heat it absorbs or emits as a function of temperature.

A DSC trace is an approximate graph of energy density with respect to temperature, the height of the trace indicating the rate at which the sample's material absorbs or emits thermal energy. DSC traces of energetic materials such as incendiaries and explosives have a characteristic shape that remains near zero up to a certain temperature range -- the ignition temperature -- and thereafter spikes sharply upward. The energy density of the material can be estimated by calculating the area under the curve.

Chips from each of the four samples, when subjected to thermal analysis using the DSC, clearly show the exothermic behavior of an energetic material. As seen in Fig. 19, the heights of the graphs vary significantly from one chip to the next. The authors attribute this variation to the fact that the chips had different ratios of active red material to inert gray material.

Based on the DSC analysis, the authors estimate the energy density of the four chips at 1.5, 3, 6, and 7.5 kJ/g, respectively. This compares with a maximum yield from conventional thermite of slightly less than 4 kJ/g. In a final section of the paper underscoring the need for further research into the red-gray chips, the authors suggest a possible explanation for the exceptional energy content of the red-layer material: perhaps elements in the porous matrix, such as oxygen, carbon, and hydrogen, contribute to the reaction.

A comparison of DSC traces of the red-gray chips to a published DSC trace from an xerogel/nano-thermite energetic nanocomposite shows the chips to be more energetic and to have a lower ignition temperature.

Ignition Residue Analysis

Because DSC processing causes the chips to ignite, the investigators studied the residues and found, not surprisingly, minute iron-rich spheroids, as well as silicon-rich spheroids. When subjected to XEDS analysis, the iron-rich spheroids showed iron far in excess of oxygen, as expected in an aluminothermic residue.

The paper contains the following micrographs and corresponding XEDS spectra of spheroids from three different sources: residue from the ignition of commercial thermite, residue from the ignition of the red-gray chips, and World Trade Center dust.

Conclusions

I hope that my review of Active Thermitic Material Discovered , being summary and somewhat interpretive, will serve as encouragement to read the paper itself, which, as scientific papers go, is remarkably accessible. The paper's conclusions -- a clear and cogent summary of the results -- are reproduced here in their entirety:

We have discovered distinctive red/gray chips in significant numbers in dust associated with the World Trade Center destruction. We have applied SEM/XEDS and other methods to characterize the small-scale structure and chemical signature of these chips, especially of their red component. The red material is most interesting and has the following characteristics: It is composed of intimately mixed aluminum, iron, oxygen, silicon and carbon. Lesser amounts of other potentially reactive elements are sometimes present, such as potassium, sulfur, barium, lead and copper. [4,6] The primary elements (Al, Fe, O, Si, C) are typically all present in particles at the scale of tens to hundreds of nanometers, and detailed XEDS mapping shows intimate mixing. On treatment with methyl-ethyl ketone solvent, some segregation of components was observed. Elemental aluminum became sufficiently concentrated to be clearly identified in the pre-ignition material. Iron oxide appears in faceted grains roughly 100 nm across whereas the aluminum appears in plate-like structures. The small size of the iron oxide particles qualifies the material to be characterized as nano-thermite or super-thermite. Analysis shows that iron and oxygen are present in a ratio consistent with Fe 2 O 3 . The red material in all four WTC dust samples was similar in this way. Iron oxide was found in the pre-ignition material whereas elemental iron was not. From the presence of elemental aluminum and iron oxide in the red material, we conclude that it contains the ingredients of thermite. As measured using DSC, the material ignites and reacts vigorously at a temperature of approximately 430ºC, with a rather narrow exotherm, matching fairly closely an independent observation on a known super-thermite sample. The low temperature of ignition and the presence of iron-oxide grains less than 120 nm show that the material is not conventional thermite (which ignites at temperatures above 900ºC) but very likely a form of super-thermite. After igniting several red/gray chips in a differential scanning calorimeter run to 700ºC, we found numerous iron-rich spheres and spheroids in the residue, indicating that a very high-temperature reaction had occurred, since the iron-rich product clearly must have been molten to form these shapes. In several spheres, elemental iron was verified since the iron content significantly exceeded the oxygen content. We conclude that a high-temperature reduction-oxidation reaction has occurred in the heated chips, namely, the thermite reaction. The spheroids produced by the DSC tests and by the flame test have an XEDS signature (Al, Fe, O, Si, C) which is depleted in carbon and aluminum relative to the original red material. This chemical signature strikingly matches the chemical signature of the spheroids produced by igniting commercial thermite, and of many of the micro-spheres found in the WTC dust. [5] The presence of an organic substance in the red material is expected for super-thermite formulations in order to produce high gas pressures upon ignition and thus make them explosive. The nature of this organic material in these chips merits further exploration. We note that it is likely also an energetic material, in that the total energy release sometimes observed in DSC tests exceeds the theoretical maximum energy of the classic thermite reaction.

Discussion

The implications of the discovery of unspent aluminothermic explosives and matching residues in World Trade Center dust are staggering. There is no conceivable reason for there to have been tons of high explosives in the Towers except to demolish them, and demolition is blatantly incompatible with the official 9/11 narrative that the skyscrapers collapsed as a result of the jetliner impacts and fires.

The discovery of active thermitic materials adds to a vast body of evidence that the total destruction of the Towers were controlled demolitions, and to the subset of that evidence indicating the use of aluminothermic materials to implement those demolitions.

That discovery also undermines the oft-heard claim that no explosives residues were found, a claim that was never compelling, given the apparent lack of evidence that any official agency looked for evidence of explosive residues of any kind. Worse, the public record shows that NIST not only failed to look for such evidence, it repeatedly evaded requests by scientists and researchers to examine numerous facts indicating explosives and incendiaries .

I expect that collapse theory defenders will dismiss the discovery of active thermitic material in the same way that they dismissed the thermite residues: by claiming that the samples were contaminated and/or that there are other explanations for the origin of these artifacts than pyrotechnics in the WTC Towers. "Debunkers" have proposed that the iron-rich spheres were fly ash residues embedded in the Towers' concrete, ignoring that the iron constituents in fly ash are oxides rather than elemental iron. How will they explain away the bi-layered chips, whose red layers have iron oxide and elemental aluminum in the ratio of Fe 2 O 3 thermite as nano-sized particles of uniform shape?

As the work of explaining away the direct evidence of explosives becomes more daunting, we will probably see even more reliance on the mainstay of arguments against controlled demolition: those alleging that insurmountable obstacles would face such a project. Three of the most salient such workability arguments are:

That the surreptitious preparation of the Twin Towers was too prone to exposure.

That setting up the demolitions to start from the Towers' crash zones was technically unfeasible.

That thermite is unsuitable as a tool of controlled demolition.

These arguments have taken on the appearance of straw men with their continued repetition -- including by NIST itself -- after being publicly shown to be based on false assumptions. The 9-11Research FAQ on Demolition addressed the first two starting in 2004, and Steven Jones and others addressed the third starting in 2006 by pointing out the existence of explosive variants of thermite.

FAQ: Controlled Demolition With Aluminothermics

With the publication of Active Thermitic Material Discovered it becomes even easier to imagine plausible scenarios that answer workability arguments. The characteristics of super-thermites and the features of the thermitic fragments described in the paper, combined with a survey of methods for the programmable wireless detonation of energetic materials available in 2001, provides straightforward answers to the most frequently-heard questions about the implementation of controlled demolition of the Twin Towers -- answers that thoroughly undermine assertions that controlled demolitions using aluminothermics was not feasible.

Following are the three arguments listed above re-phrased as questions. I start with the last argument, which is addressed in detail in the discussion section of Active Thermitic Material Discovered .

How Could Thermite, an Incendiary, Demolish the Towers, When Buildings Are Normally Demolished Using High-Explosive Cutter Charges?

As is obvious from a review of the literature on energetic materials, thermite-based pyrotechnics can be engineered to have explosive power similar to conventional high-explosives while providing greater energy density and much greater stability. Thus, aluminothermic cutter charges similar to the shaped charges used in commercial demolitions are entirely feasible. However, a variety of forms of thermite might be used to demolish a steel-framed skyscraper in a way that uses no cutter charges at all, as in this Hypothetical Blasting Scenario, which posits three types of aluminothermic pyrotechnics: a thermate incendiary coating sprayed onto steelwork, nano-thermite kicker charges placed near steelwork, and thin-film nano-composite high-explosives distributed throughout the building. The strategically applied incendiary coatings, ignited several minutes before the building's take-down, weaken the structure; but obvious failures start only when the kicker charges break key supports, and the thin-film high-explosives begin pulverizing the building from the initial failure zone outward.

Why Weren't Demolition Charges Triggered by the Plane Crashes or the Subsequent Fires?

Perhaps the plane crashes did trigger some of the charges. If so, their blasts were lost in the jet-crash fireballs, and their damage was insufficient to budge the Towers' tops. Thermite incendiaries in the core ignited by the crash would not be visible over the fires, unless dislodged to the building's exterior, as apparently happened in the South Tower. However, this probably wasn't an issue because, in contrast to conventional explosives, thermite has a very high ignition temperature -- above 900ºC. Thus, thermitic incendiaries used around the crash zones could have been designed to survive the fires. As for thermitic explosives, they could have been designed to detonate only on exposure to the very extreme conditions of temperature and pressure provided by specialized detonators, and to deflagrate (merely burn) in response to the kinds of pressures and temperatures produced by the plane crashes and fires. As a fail-safe, the demolition sequence could have been programmed to be triggered by premature ignitions of pyrotechnics.

How Could the Demolition Equipment Have Been Installed in the Twin Towers Without Tenants Noticing?

The simple answer is by disguising the equipment as normal building components, so that not even the workers installing the components are aware of the concealed pyrotechnics. Three aspects of the Hypothetical Blasting Scenario that facilitate this are: the stability and specificity of ignition conditions achievable with aluminothermic pyrotechnics, minimization of the required access to steelwork, and the use of a completely wireless ignition control system.

Glossary of Analytical Methods

BSE: Backscattered Electron imaging

A method of SEM imaging based on the detection of scattering of the electron beam.

DSC: Differential Scanning Calorimetry

A technique that determines the difference in the amount of heat required to increase the temperature of an experimental sample and reference. A differential scanning calorimeter outputs a DSC trace which shows the relationship of heat flux to temperature, and thereby exothermic or endothermic behavior of the sample. [23]

SEM: Scanning Electron Microscopy

A type of electron microscopy in which a beam of high-energy electrons scans the surface to a sample to image its structure or composition.

XEDS: X-ray Energy-Dispersive Spectroscopy

A technique for determining the elemental composition of a sample using an instrument that analyzes the spectrum of emitted X-rays from a sample as a beam of high energy electrons is directed onto its surface. [24]

A single workstation may provide integrated BSE and XEDS capabilities using SEM equipment fitted with specialized BSE and XEDS detectors, where software controls the electron beam, sample positioning, and detector parameters.

References