The U.S. Navy detected, through the use of a top-secret military acoustic system, what it suspected was the implosion of the Titan submersible Sunday and shared the information with the Coast Guard to help with the search, and opted to "to continue our mission as a search and rescue and make every effort to save the lives on board," according to a senior Navy official.
The signal was picked up within hours after the Titan was reported lost while on its way to view the ruins of the Titanic, with the Navy beginning to listen for it almost as soon as it lost communications, The Wall Street Journal reported.
After the signal was picked up, near what eventually was discovered as the Titan's debris site Thursday, the Navy reported its findings to the Coast Guard.
Officials said the Navy could not definitively say the sound had come from the Titan, but the discovery helped narrow the search for the sub.
"The U.S. Navy conducted an analysis of acoustic data and detected an anomaly consistent with an implosion or explosion in the general vicinity of where the Titan submersible was operating when communications were lost," the senior U.S. Navy official said in a statement. "While not definitive, this information was immediately shared with the Incident Commander to assist with the ongoing search and rescue mission."
The Navy has asked that the system that was used not be named, as it is normally used to detect enemy submarines. The U.S. developed acoustic systems to detect submarines in the Atlantic and Pacific Oceans after World War II.
The search for the Titan took place about 900 miles off the coast of Massachusetts, and searchers on Thursday found the debris from its wreckage about 1,600 feet from the bow of the sunken Titanic, said the U.S. Coast Guard. Ships from the United States, France, and Canada were included in the search mission.
The Coast Guard has not responded to requests for comment about the information it got from the Navy or how it was used in the search.
U.S. and Canadian officials said rescue crews detected several types of noises during the search, including the one believed to have been the implosion.
Underwater implosions occur suddenly when the pressure of seawater overpowers pressure inside a submarine, crushing it.
Searchers also said they heard sounds that they thought could be knocking from the Titan but could not conclude the noises came from the vessel.
The search area grew to be twice the size of the state of Connecticut but eventually narrowed. It was not made clear what caused the area to shrink, but a U.S. defense official said the acoustic data analysis was a "significant factor" in locating the debris field.
An investigation is expected to try to determine whether the sound believed to be the implosion was from the Titan, but a defense official said it's not clear which government entity would handle it, an official said.
Meanwhile, defense officials said they did not go public with the sounds that had been detected as they wanted to be sure that the search-and-rescue mission continued, and also because the Navy could not guarantee that the sound was definitely that of an implosion.
Meanwhile, the five men who were aboard the Titan are believed to be dead, the Coast Guard and OceanGate, the company operating the submersible, said Thursday.
Their families were informed Thursday of the Navy's findings when the debris field was found.