The noises give hope, but the oxygen in the missing submarine should run out this morning.

The sounds were first picked up Tuesday evening by a sonar buoy dropped by a Canadian aircraft, prompting the US Coast Guard to focus efforts on finding the flagged area.

New noises were discovered on Wednesday and several sources said they may have been caused by the crew regularly hitting the ship’s hull to help in the search, but authorities have not confirmed.

“Frankly, we don’t know what the origin of these sounds is,” said Commander Jamie Frederick, a spokesman for the mission.

Several remote-controlled submersibles scanned the marked area throughout the day, but found no sign of the submarine that disappeared on Sunday while diving for the wreck of the Titanic.

On Wednesday night, a French scientific ship was expected to arrive at the site, carrying an underwater robot capable of reaching the depth at which the device should be located – more than 3800 meters.

If he could find it, the plan was to try and attach a cable to the submersible and lift it to the surface with two giant cranes, in a real race against time before the oxygen on board ran out. An almost impossible mission.