RDX Links Russian Crashes

Traces of RDX, a common military explosive that is also known as hexogen or cyclonite, were found at the crash sites of two Russian planes that went down within minutes of each other on Aug. 24, Russian authorities report. RDX was also used in a suicide bombing at a Moscow metro station on Aug. 31, news reports say.

"RDX is a very powerful explosive," says Jimmie C. Oxley, a professor of chemistry at the University of Rhode Island. "A terrorist wouldn't need to conceal very much." RDX has an explosive power considerably greater than that of TNT, is chemically stable, and is more susceptible than TNT to shock detonation.

U.S. security officials are familiar with RDX, Oxley says, and airport screening equipment is standardized to detect it.

First, all checked luggage in U.S. airports goes through an X-ray imaging explosives-detecting system. Second, passengers and carry-on luggage can be randomly selected for additional screening. Carry-on luggage is swabbed for particulates, and the swabs are sent through an ion-mobility spectrometer. For this part of the system to work, an explosive particulate has to transfer to a bag, the bag must be selected for screening, and the swab must pick up the particulate.

The Transportation Security Administration is also trying out a new explosives detection machine at five airports. The GE Entryscan looks like a large metal detector and blows puffs of air onto a passenger. Any particulates that are blown off are collected and analyzed. In addition, TSA plans to test a new document-scanning machine that detects traces of explosives on boarding tickets.