What does all that have to do with anything? Well, one of the air show stalwarts, and my all-time favorite military plane, is the A-10 Thunderbolt II, aka the Warthog. I'm absolutely fascinated by the things, and it's cool to see one buzzing the city without the pants-wetting terror that would normally accompany the sudden appearance of ground attack aircraft. The A-10 is very nearly a flying tank, with absurd survivability and a weapons payload second only to dedicated bombers and AC-130 close air support planes.
The A-10 can carry up to 16,000 pounds of under-wing ordinance, but what really fascinates me is the A-10's signature weapon - a nose-mounted GAU-8 Avenger 30mm Gatling. Actually, nose-mounted is a poor term, since the weapon only protrudes from the nose. The weapon itself is actually somewhere on the order of 6.4 meters long. The GAU-8 is used to kill tanks, and it does so using a special type of munition, which is what I want to talk about today.
Tanks, as one might guess, are armored. Defeating the armor on modern tanks is no simple task, which has lead to the development of a type of munition called a discarding penetrator, or sabot. Basically, sabots are projectiles that, after being fired, cast off a large part of their mass leaving behind an extremely high velocity slug. In general, penetration is aided by using a dense material. In the early days, high carbon steel was used, then tungsten carbide. In modern times, the most effective material for penetrator rounds is depleted uranium.
So what the hell is depleted uranium? Depleted uranium, or DU, is mostly composed of uranium isotope 238, which is what's left over when uranium is enriched into uranium isotope 235. It's an extraordinarily dense material, it self-sharpens as it passes through other hard materials, and that same self-sharpening action causes it give off pyrophoric dust that can spontaneously ignite. It's nasty stuff, and bullets made from it are great for taking out armored targets. The gatling gun on an A-10 uses DU rounds (specifically the PGU-14/B API round), as does the vulcan on the AH-64 Apache Attack Helicopter.
DU is still radioactive, though far less so than other kinds of uranium. You won't get sick from incidental exposure to it in its solid state, but you don't want to breath the dust from it, ingest it, or line your underpants with the stuff. Consumption and very long-term exposure can cause severe kidney damage, and breathing the dust can cause an increased incidence of lung cancer. The primary risk here is for soldiers - vehicles struck by DU penetrators can have large amounts of DU dust floating around in them, and DU-armored vehicles (such as the heavy armor conversion of the M-1 Abrams) can give off clouds of the stuff if they're set ablaze. In general though, short term exposure is unlikely to be dangerous.
The actual radiological risks of DU are negligible, but in some cases the chemical risks may not be. There are concerns that DU can cause harmful effects through the contamination of water. You see, DU deteriorates when exposed to water and can breakdown into toxic soluble uranium salts. The Navy even went so far as to abandon DU rounds as the munition of choice for CIWS defensive guns on its warships because of concerns about large amounts of DU contaminating ocean water. There are also questions about the contamination of ground water resources due to DU rounds that miss their targets and then break down into the water table.
There is some concern that DU contamination may eventually play a role in the future of
In any event, the calculus of war is a complicated thing, and insidious, often hidden factors like the potentially harmful effects of expended DU munitions only compound this complexity. While I don't expect that the DU will prove itself to be as destructive as anti-personnel landmines in terms of post-conflict civilian casualties, epidemiological studies of populations living in areas with relatively high DU exposure should be be undertaken to determine whether there are additional health risks involved with the use of such munitions.
This is especially important in "wars of liberation" like the one being fought in
Thursday, April 10, 2008
The Complicated Calculus of Conflict...