The two bombs disguised in toner cartridges and sent from Yemen in November were specifically designed to foil both x-ray machines and trace particle detectors, the Department of Homeland Security’s top technologist said Dec. 14.
The bombs were “clearly” fabricated in a way to fool baggage screening technologies, Tara O’Toole, undersecretary of the science and technology division said.
“They were anticipating our x-ray devices. They were anticipating the possibility of trace [explosives] detection,” she said at a National Defense Industrial Association luncheon. She did not elaborate on whether the two bombs underwent screening. However, it has been widely reported that the plot was uncovered through human intelligence rather than technology.
Al-Qaida of the Arabian Peninsula on an online magazine said it hid PETN explosives in cartridges because toner is carbon-based, with a chemical composition close to that of PETN. “We emptied the toner cartridge from its contents and filled it with 340 grams of PETN,” the magazine said, according to the Site Intelligence Group, which monitors terrorist websites.
The Yemen group boasted of how economical it was to carry out the attack. The shipping transportation and the bomb components reportedly cost $4,200. Experts at the Transportation Security Laboratory in Atlantic City told National Defense Magazine that it was impossible to make a “clean bomb” — one in which no molecules escape the construction of the manufacturing process. Other experts have noted that PETN, an odorless, white crystal material, is hard to detect because it has a low vapor pressure and few of its molecules escape into the air around the bomb, where it can be detected by either trace explosive technologies or bomb sniffing dogs, said the Globalsecurity.org website.
PETN has been a component used in terrorist plots against airliners since the 1988 Lockerbie bomb. Richard Reid, the shoe-bomber, and Umar Farouk Abdulmutallab, the accused Christmas Day terrorist who allegedly hid explosives in his underwear, both possessed PETN.
O’Toole said DHS will be moving away from funding basic research except in a few select programs. The department’s science division is more interested in investing in technologies that can be fielded in 18 to 24 months. Explosive detection was one discipline she mentioned that would continue to receive support for what she described as “science projects.”