A Canadian military surveillance aircraft has detected underwater noises as a massive search goes on in a remote part of the North Atlantic for a submersible that vanished while taking five people down to the wreck of the Titanic. A statement early Wednesday from the U.S. Coast Guard did not elaborate on what rescuers believed the noises could be. However, it offered a glimmer of hope for those now lost abroad the Titan as estimates suggest as little as a day’s worth of oxygen could be left if the vessel is still functioning. Meanwhile, questions remain on how teams could reach the lost submersible, which could be as deep as about 12,500 feet below the surface near the watery tomb of the historic ocean liner.