A French vessel, equipped with special detection equipment to locate the pings, will begin an underwater search for the wreckage. It departed Tuesday from Porto Vecchio toward the Egyptian coast. An underwater exploration robot will also possibly be used. The search is ongoing for the critical parts of the plane, including the fuselage, flight data and cockpit voice recorders. Egyptian authorities have retained foreign companies that specialize in marine wreckage searches and whose equipment can survey the depths in the crash area, believed to be around 10,000 feet deep. Finding the plane’s wreckage will allow investigators to glean information about how it crashed. It can also point to signs that explosives were used. For the instant, no possible cause for the crash has been ruled out. A week after the Airbus A320 crashed investigators have no clear picture of its final moments.