Members of the Argentine Navy search the sea from an airplane for signs of the missing submarine.

A member of the U.S. Navy, aboard a Boeing P-8A Poseidon plane, places a sonobuoy in the launching compartment to drop into the South Atlantic Ocean during the search for the ARA San Juan submarine. Sonobuoys are an expendable sonar system that can detect submarines or other objects underwater.

A woman touches a poster of snapshots of Celso Oscar Vallejo, one of the crew members of the missing ARA San Juan, that hangs on a fence at the Mar del Plata Naval Base, in Argentina, Thursday.

An Argenitine Navy officer and a relative of one of the 44 crew members of the missing at sea ARA San Juan submarine console each other at a naval base in Mar del Plata, Argentina, Thursday.

A member of the U.S. Navy, aboard the Boeing P-8A Poseidon aircraft, looks down at the the South Atlantic Ocean during the search for the ARA San Juan submarine on Wednesday.

A woman cries outside the Mar de Plata Naval Base after learning that Argentina's navy announced that a sound detected during the search for the missing ARA San Juan submarine is consistent with that of an explosion.