Sonar buoys deployed by a Canadian P-3 plane have detected underwater sounds and renewed the hope of the search team. The search for the missing Titanic tourist sub that disappeared near the 1912 wreckage of the Titanic has become a race against time.

With each passing moment, the limited oxygen supply onboard becomes more of a  threat to the crew's survival. As time slips away, experts estimate that only a day's worth of oxygen may remain. 

The US Navy experts are analyzing the underwater sounds picked up by the sonar buoys, hoping to pinpoint the vessel's exact location. Crews, braving the harsh conditions of the remote North Atlantic, have been actively investigating the source of the noises.

The US Coast Guard has remained tight-lipped about the nature of the noises detected. An internal US government memo obtained by several media outlets revealed that banging sounds were heard at 30-minute intervals on Tuesday. And the underwater acoustic sonar buoys may be the last hope.

Sonar buoys hear banging sounds

 Additional sonar scans conducted hours later confirmed the persistence of these sounds. Despite deploying remotely operated vehicles (ROVs), search teams have yet to find any further clues.

The search and rescue operation still hopes that the vessel remains intact. And that the crew is sending an SOS from the small submarine. The passengers were sealed inside the sub using external bolts. And they cannot escape from it by themselves.

Deep-sea experts have emphasized the need to analyze the data in order to determine the origin of these mysterious noises. The search operation's commander has confirmed that the source remains unknown.

Chris Brown, an explorer, and friend of one of the crew members, suggests that the reported banging sounds could be an intentional means of communication by the trapped individuals. He speculates that they might be conserving oxygen and energy in the cold and dark depths of the ocean.

The vessel was carrying a total of five individuals when contact was lost during its dive. At that point, it had descended more than halfway towards the Titanic wreck, reaching a depth of approximately 1,900 meters (6,233 feet) beneath the surface.

 The crew members include British businessmen Hamish Harding and Shahzada Dawood, along with his son Suleman, French explorer Paul-Henry Nargeolet, and Stockton Rush, the CEO of OceanGate, the company which owns the Titan.

The mission is challenging, with no communication from the Titan sub and poor visibility once below the water's surface. The search area, spanning an enormous 7,600 square miles (19,683 square km) - larger than the US state of Connecticut, has been scoured thus far.

Despite adverse weather conditions, improvements on Tuesday have allowed for increased search operations.

The extensive search operation involves cooperation among US and Canadian agencies, navies, and commercial deep-sea firms, all coordinated from Boston, Massachusetts. Military planes, submarines, and sonar buoys are being used.

On the last day of the oxygen supply hope hangs in the balance. And the search continues to be driven by the possibility of rescuing the crew alive.