Thursday, July 21, 2005

Homemade Bombs

Two weeks ago, I wrote a post about the terrorist attack that struck the public transportation system in London, killing over 50 people. Today, bombers struck the London "Tube" system again, although early reports indicate the explosions were much smaller than the ones two weeks ago.

What most people do not realize is how readily available the ingredients are that can be used to make a workable bomb. According to news reports, the London Tube bombings two weeks ago used a crude explosive called triacetone triperoxide (TATP). TATP is also the explosive that was packed into the shoes of Richard Reid, the infamous "shoe bomber" who tried to bring down a transatlantic flight with it. TATP is a powerful explosive, but is highly unstable (meaning it can blow up when you don't want it to), making it too unsafe for use for any "normal" purpose. But, for a terrorist, it is an explosive of choice, due to the ready availability of the ingredients: TATP can be made from a combination of paint thinner, an antiseptic first-aid solution, and toilet bowl cleaner, and using equipment you can find in a typical household kitchen. However, TATP is very dangerous to make, and the maker also needs to know enough about chemistry to calculate the ratios to mix the ingredients in, what temperature to make it at, how to keep the solution at that temperature while the chemical reaction is going on, how to separate out the product, and how to do all this without it blowing up in his face.

Another type of explosive that has been used by terrorists is Ammonium Nitrate / Fuel Oil (ANFO), an explosive that is frequently used in the mining industry. America's notorious "home-grown terrorist" Timothy McVeigh used a large amount of ANFO packed into a rental truck to bring down the Federal Building in Oklahoma City in 1995. The ANFO he used was made by a combination of fertilizer and diesel fuel, and while ANFO is not a very powerful explosive, when you use a large amount of it (McVeigh used a whole truckload) it can do a lot of damage. And (more importantly for McVeigh) the ingredients were available from his local farm supply store and his local gas station!

I remember when I was studying chemistry in university, thinking to myself how lucky we all are that most people in the world do not know these skills I was learning. Any university-educated chemist is capable of making explosives, and at the college I studied at, a number of people liked to experiment with them for fun. The year before I got there, one student was expelled when they caught him with a beaker of the high explosive TNT cooking under a fume hood. And, I will never forget one evening while I was there and a group of students detonated a test bomb that was so powerful it shook the ground and shattered windows around the whole campus. Explosive compounds like NI3 and thermite were occasionally made in small quantities for use in practical jokes.

Needless to say, it is a good thing that the vast majority of chemists are like me: good hearted people with benign intentions, who use our scientific knowledge for productive purposes. We would all be in a whole lot of trouble if this were not the case.