*Richard Wolkomir / DISCOVER / AUG 89 / 77:81*
* Fifty miles outside Trinity, New Mexico, the spot where the first atomic
bomb was detonated, mangled warplanes -- ancient B-36's, B-57's, and F-86's --
lie strewn across the desert floor. From the looks of things the aircraft
were intact when they arrived, but since then something has done them serious
On a road to the east, where the town of Socorro sits on the bank of the Rio
Grande, a van bounces along in the dust, carrying four men in hard hats. The
van disappears into the mountains; a siren wails; wails again a few minutes
later; and then:
In far-off Socorro the resounding blast shakes California Street, the town's
main drag. But nobody pays it any mind; they're all quite used to it. This
sunbaked community and adjacent mountain test site are home to the New Mexico
Institute of Mining & Technology, where they have a simple mission in life:
blow up things. The institute is the nation's leading facility for explosives
* Actually, the institute houses two facilities. The oldest, which test
munitions and armor for the military, is the Terminal Effects Research &
Analysis Group. An offshoot of World War II ordnance research, the Terminal
Effects Group was settled at Socorro in 1949, at a site made attractive by its
desert emptiness and the proximity of the White Sands Missile Range and the
Air Force Weapons Laboratory. This is what created the aircraft graveyard:
the jets were targets used to measure the damage caused by specific munitions.
The other facility, the Center for Explosives Technology Research, does less
warlike work. This branch of the institute was set up in 1983 to develop
industrial and commercial applications of explosives. Every month they set
off dozens of explosions, ranging from popgun bursts to ground-shaking
It's early morning, but materials scientists Marc Meyers and Naresh Thadhani
have already begun preparing the day's explosion. Parking their van outside
the Big Eagle firing bunker, a thick-walled concrete structure buried in the
side of a mountain, they begin unloading wires, fuzes, bomb cases. Today's
experiment is a relatively routine one: using a volatile mixture known as
ANFO -- a combination of ammonium nitrate and fuel oil -- they will try to
transform a mix of powders into a solid superconducting ceramic.
[ED: According to a certain voluble redneck I happen to know, this is roughly
the explosive used in the OKC bombing -- you mix nitrate fertilizer with
diesel until it has the consistency of toothpaste ... not that I'd want to try
such an experiment myself, by any means. I recall stories of a cargo ship
carrying nitrate fertilizer that leveled a Gulf Coast town during World War II
when it caught fire and its diesel tanks ruptured.]
Traditionally, superconducting powders are fused into ceramics in powerful
presses or ovens. The high temperatures are necessary for the powders to
fuse, but if they overheat, the ceramic can break down and lose its
superconducting properties. The process is also slow; the powders must be
pressed or baked repeatedly. Explosives, however, can do the job in a few
millionths of a second. When the charge is detonated, the shock wave moves
through the powders at more than 11,000 feet per second, squeezing the grains
together violently. The surfaces of the grains melt and fuse, but the
interior of each stays solid.
Big Eagle is jammed with equipment, but the experiment Meyers and Thadhani rig
up appears home-built. A copper capsule a few inches long is filled with
superconducting powders and set on a plate. Around the capsule the two men
place a section of black plastic pipe, which they fill with 4 pounds of ANFO.
The stuff looks like coarse sand and smells of fuel oil. Meyers and Thadhani
then attach a detonator and run a cable to the bunker.
They return to the bunker and close the door, sound the warning siren twice,
and then press a button to send 2500 volts to the detonator. There is a flash
of light, a loud thud, a shower of black debris -- and all that is left is the
twisted copper cylinder.
Thadhani emerges to poke at the still-hot cylinder. "The last time we tried
this, we used 8 pounds of ANFO," he says. "But the intense pressure
generated by the explosion caused the ceramic to crack. This time we used
only 4 pounds." The contents of the cylinder will be taken back to the lab
to be analyzed and fine-tune the technique.
* There are thousands of types of chemical explosives -- familiar ones include
black powder, TNT, and ANFO -- and they typically involve fusing
oxygen-nitrogen compounds with hydrogen-carbon compounds. When the two are
confined together and excited by heat or shock, the nitrogen breaks its
electron bonds with the oxygen; then the free oxygen mingles with the carbon
or hydrogen, instantly forming intense heat, water vapor, and other gases.
"An explosion's pressure can reach several million pounds per square inch,"
says Fred Sandstrom, an explosion specialist who is involved in the
superconductor studies. A single kilogram of TNT delivers about 5000
megawatts of power for a split second.
The earliest recorded explosives were devised by Byzantine Greek alchemists in
the 7th century; they found that a nasty brew of pitch, naptha, sulfur, and
petroleum would burst violently when ignited. The mix was known as Greek
fire; the empire's military used it to defend Constantinople from invading
Greek fire was an unstable and inconvenient explosive. Around the year 1000
AD the first really usable explosive -- black powder -- was invented. It
is not known for certain who discovered that a mixture of potassium nitrate
(saltpeter), sulfur, and charcoal gets violent when lit, but most scholars
credit the Chinese, who used it in fireworks and signals. The new mixture
found its way into cannons, muskets, and bombs.
The next big breakthrough came in 1846, when an Italian chemist named Ascanio
Sobrero added glycerol to a mixture of nitric and sulfuric acids and nearly
killed himself in the resulting explosion. Sobrero decided that the stuff he
called nitroglycerine was too dangerous and tried to keep it a secret. He
failed; Sweden's Nobel family obtained the formula and began manufacturing it
as "blasting oil" for mining.
Some years later Alfred Nobel invented the less volatile substance he called
dynamite, named for the Greek "dynamis", or "power". By mixing dynamite with
a porous, siliceous material, he created a compound he could drop, hammer, or
even burn without causing it to explode. When subjected to the strong
percussive shock of a blasting cap, however, it delivered as powerful an
explosion as pure nitroglycerine.
Dynamite was the first really convenient explosive and proved so popular that
Nobel was publicly labeled the "merchant of death"; he established the Nobel
prize to help uphold his family's dignity. After dynamite came the deluge;
there are as many as 20,000 different explosives today. Many are variations
on black powder or TNT. Many are entirely new compounds.
* There is still plenty of work on improving explosives for use in warfare,
but the Center for Explosives Technology Research remains focused on more
constructive applications. In the same labs where the superconducting work is
being done, Thadhani shows off a small square of metal, a lightweight laminate
composed of 15 alternating layers of aluminum foil and piano-wire mesh with an
unusually high strength-to-weight ratio.
To create the composite, the researchers stack thin layers of foil and mesh
until they have a sandwich that's a quarter to half-inch high. On top of that
they place a metal sheet called a flyer plate; and on top of that they place a
layer of powdered ANFO. Only the upper surface of the explosive is exposed to
the air; since the shock wave of the explosion moves faster through the solid
material below than through the air above, when the ANFO blows, it blows
mostly downward. This causes the flyer plate to compress the layers into a
single, fused unit.
The new material could be used for armor or lightweight aerospace structures.
It can be manufactured much more readily and cheaply than other laminates,
most of which are either liquified and poured into molds or welded together in
hot presses. There is no need for clean production facilities, either; the
blast vaporizes the metal between the layers, scouring impurities out of the
Explosive manufacturing sometimes requires a more focused blast, however, and
a device called an explosive plane wave lens is required, which delivers a
hammer-blow shock in just one direction. Essentially the lens is a plate
topped by a disk of explosive and then two-layer cone of explosive material; a
solid inner cone molded out of a relatively slow-blowing explosive, and an
outer layer of faster-burning material. The two cones allow the explosive to
burn evenly; if the entire cone was made of the same explosive, the outer
parts -- with farther to travel -- would take longer to combust than the inner
part, and the charge at the bottom would not be detonated at one time.
Thadhani and his colleagues are using the explosive lens to build industrial
diamonds of unsurpassed quality. Natural diamonds are formed from carbon
under pressure for eons in deeply buried rock; an explosive lens can be used
to generate the same or greater pressures for a short period of time.
The researchers pack diamond powder into square-inch stainless-steel capsules
and then pack the capsules into a metal holder. An explosive lens is used to
subject this assembly to a million times the air pressure at sea level. The
results are big polycrystalline industrial diamonds, half an inch in diameter
and 85% as hard as natural diamonds, a record for artificial diamonds.
"They're dark and ugly," says lab manager Ed Roy, "but they're perfect for
industrial jobs like slicing metals."
Another project at the center involves explosive welding; studies have shown
that if two pieces of metal are driven into each other by an explosive blast,
they will form a weld far superior to that obtained with a welding torch.
"Ordinary welding," says the center's assistant director, Pharris Williams,
"leaves microscopic gaps that can lead to oxidation and corrosion. With
explosion welding, the materials interlock so snugly that corrosion isn't
Explosive welding is now being used in the construction of nuclear power
plants; explosive plugs are fitted into pipes and then detonated, sealing tiny
leaks. The method is also being used in Europe for welding rails for
Yet another application of explosives is of course mining. "Say you've
discovered a lode of coal under a hundred and 150 feet of earth, sandstone,
and shale," says Roy. "Ordinarily, you'd have to dig it all up with
bulldozers. But newer compounds can put out more heave over a longer period
of time. This can expose millions of tons of coal and keep a mining company
busy for months."
* Despite these interesting applications, most of the facility's focus is not
on building bigger bangs, but on making safer ones. For example, explosives
are often used to clear sand-blocked oil channels at the bottoms of deep
wells, but the temperatures 15,000 feet below the ground are often enough to
detonate the charges before they reach their proper objective, causing more
harm than good. The center hopes to correct this problem by developing
"An insensitive explosive," says Roy, "is essentially a buffered explosive.
We've developed a way to bond a plastic compound to each crystal of an
explosive material. This services to stabilize the explosive chemically,
physically, and thermally. Insensitive explosives go off only when you want
them to go off."
The military is of course busy in this field as well. "A Navy ship may be
filled with missiles, aircraft, and fixed ammunition," says Roy. "That's a
very dangerous vessel. If it takes a hostile strike, an entire ordnance
magazine can be set off. As a result, the military has its own drive on to
develop insensitive explosives. What they learn they're transferring to us,
and what we learn we're transferring to them."
"We're working on explosives that don't accidentally do anything," says the
center's director, Per-Anders Persson. "Some already have the qualities of a
block of wood unless they're detonated by a charge of the right size and
power." He is interested in developing "smart" detonators -- fuzes with
silicon smarts that won't fire unless given a code sequence that is unlikely
to occur by accident.
Persson was recently summoned to help diagnose what went wrong at a Nevada
chemical plant where an explosion in the spring of 1988 killed two people,
injured more than 100 others, and destroyed a substantial portion of a key
ingredient used in the space shuttle's solid fuel. His role in this has
helped drive another one of the center's efforts: finding ways to store
volatile materials for long periods with minimum risk.
"We're learning how to handle these materials better and feel safer around
them," says chemist Jimmie Oxley. To Oxley, the explosives are merely tools.
"I once had my students analyze the energy in a Snickers candy bar; it turned
out to be equal to a couple grams of TNT," she says. "The only difference
between the dynamite and the candy is that the dynamite releases its energy a
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