It is not easy to make TNT, as I once discovered by boiling toluene and nitric acid during a school lunchtime to no great effect. Neither is it terribly hard—recipes can be found on the web, and the raw materials at DIY shops—but a little chemical experience provides some perspective on how difficult it is to concoct an aircraft-busting explosive in the cabin toilet. So it is not surprising chemists have expressed doubts about the alleged plot to blow up transatlantic flights. Could two liquids really be combined on a plane to make an instant explosive?
The plotters were supposedly going to mix up triacetone triperoxide (TATP), an explosive allegedly used in the 7/7 London bombings. In principle TATP can be made from hydrogen peroxide (bleach), acetone (paint thinner) and sulphuric acid (drain cleaner). But like much chemistry, it's not that simple. The ingredients have to be highly concentrated, so can't easily be passed off as mineral water or shampoo. The reaction needs to be carried out at low temperature. And even if you succeed in making TATP, it isn't dangerous until purified and crystallised. In other words, you'd be smuggling not just highly potent liquids into the aeroplane loo but also a refrigerant and distilling apparatus—and the job might take several hours.
Why not just smuggle a ready-made liquid explosive on board? Some reports suggested that the plotters actually intended to use bottled nitroglycerine. But you'd need a lot of it to do serious damage, and it is so sensitive that it could easily go off during check-in. The same is true for pure TATP itself (a solid resembling sugar), which is why the suggestion that it was used for the tube bombings has met with some scepticism.
What does this mean for the current security measures? It is hard to understand the obsession with liquids and gels. It is not clear that there is any vital component of any "mixable" explosive that would be odourless and pass a "swig test," let alone be feasibly used in flight to brew up a lethal charge. Why are solids not subject to such scrutiny? In any case, most explosives, including TATP, are volatile, emitting fumes that can be detected at very low concentrations.
When airports instigated the "no liquids" policy in August, they were making an understandable quick response to a poorly understood threat. But they are now at risk of perpetuating a myth about how easy it is to do complex chemistry.
Fly-tipping in space
Smashing spacecraft into celestial bodies has become something of a craze. In 1999, scientists disposed of the Lunar Prospector craft, at the end of its mission to survey the moon for ice and magnetic fields, by crashing it into a lunar crater in the hope the impact would throw up evidence of water (it didn't). The Deep Impact mission ploughed into the comet Tempel 1 last February, revealing a puff of ice hidden below the surface. A rocket stage which in 2008 will be used to send a new satellite to the moon has been proposed for a re-run of the Prospector experiment. And the THOR mission pencilled in for 2011 would send a 100kg copper projectile crashing into Mars, creating a 50-metre wide crater and possibly ejecting ice, organic compounds and other materials.
The most recent of these kamikaze missions is SMART-1, the European Space Agency's moon-observing satellite, which ended its career on 3rd September by smashing into the lunar Lake of Excellence. Again, the aim was to analyse images of the impact to identify the chemical composition of the debris. SMART-1 had been active for longer than originally expected, and its experimental ion-thrust propulsion system was exhausted, making a lunar crash landing inevitable anyway. This was another case of wringing a last bit of value from a moribund mission.
The disposal of a washing-machine-size probe on the moon is hardly the most heinous act of fly-tipping—but it can't be long before this trend starts to raise mutters of environmental disapproval. Perhaps we can clear up the mess when we return to the moon. Lockheed Martin was recently awarded the Nasa contract to build the Orion Crew Exploration Vehicle, the replacement for the beleaguered space shuttle and the basis of a new manned moon shot. Scheduled for 2014 at the latest, Orion will ditch the airplane chic of the shuttle, comprising a single-use tubular rocket with a lunar lander and re-entry capsule in its tip, the latter provided with heat shield and parachutes. Lockheed Martin has presumably been working hard on this design, but cynics may suspect they just stole the idea from that film with Tom Hanks in it.
Cleanliness and sin
Shakespeare's insight into the human psyche is vindicated once again. The impulse to wash after committing an unethical act, immortalised in Lady Macbeth's "Out, damned spot!", has been confirmed as a genuine psychological phenomenon. Two social scientists say that "cleansing-related words" were more readily produced in tests by subjects who had first been asked to recall an unethical deed. The subjects were also more likely to take a proffered antiseptic wipe—and, rather alarmingly, such cleansing seemed to expunge their guilt and make them less likely to show philanthropic behaviour afterwards. So it seems there is nothing particularly godly about cleanliness.
