The first photos of the underpants bomb that Umar Farouk Abdulmutallab allegedly tried to detonate on a Northwest Airlines flight above Detroit on Christmas Day have been released. Experts have since been debating whether the explosive, if properly detonated by the 23-year-old Nigerian suspect, would have caused enough damage to bring down the transatlantic airliner. According to the US Justice Department, Abdulmutallab tried to detonate PETN, an explosive powder also known as penta-erythritol which belongs to the same chemical family as nitroglycerin. It was the same explosive used by "shoe-bomber" Richard Reid, the Briton convicted of trying to detonate explosives hidden in his shoes while on a Paris-Miami flight in December 2001. The material was sewn into Abdulmutallab's underwear and officials say tragedy was averted only because the makeshift detonator failed to work properly. <br/><br/>