PENTAERYTHRITOL tetranitrate, or PETN, is a major ingredient of Semtex and belongs to the same chemical family as nitroglycerin. It is one of the most powerful explosives made today and is a favourite among terrorists because its colourless crystals are hard to detect in a sealed container.
PETN is relatively stable and is detonated either by heat or a shockwave. A little more than 100g of the substance could destroy a car, experts say. Richard Reid, the “shoe bomber”, tried to set off a PETN device on an American Airlines jet to Miami in 2001, while this summer and a suicide bomber tried to assassinate a member of the Saudi royal family with a PETN- based bomb inside his body.
“If you can lay your hands on a reliable source, it would be the explosive of choice,” said Hans Michels, an explosives expert at Imperial College, London.
In December, PETN was found in the possession of Nigerian Umar Farouk Abdulmutallab.
According to US security officials, he had attempted to blow up Northwest Airlines flight 253 as it approached Detroit airport from Amsterdam. Abdulmutallab (23) was in a window seat and had the device strapped to his left leg, against the body of the aircraft.
The idea was almost certainly to blow a hole in the aircraft so decompression would tear it apart.
Abdulmutallab’s bomb involved a syringe and a soft plastic container filled with 80g of PETN. Experts believe the syringe may have been converted into an electrical detonator or, more likely, it was filled with a liquid detonator which would have made the device extremely hard to detect through the usual airport security measures.
Abdulmutallab cleared security in Lagos and Amsterdam after passing through a metal detector and having his hand luggage X-rayed. The lack of an explosion on the flight meant there was almost certainly a failure between the primary and the main charge so that the PETN did not fully detonate.
A test explosion on a decommissioned Boeing 747 in March showed that the flight would have landed safely even if Abdulmutallab’s bomb had detonated. In the test, carried out by Dr John Wyatt, an explosives adviser to the UN, the fuselage did not break open. Experts say the test blast showed the suspected bomber and the passenger next to him would have been killed.
ROBIN McKIE(Guardian service)