Knocks are recorded every 30 minutes. Canadian aircraft using underwater sonar devices called “sonobuoys” to search.
This gave rise to new hope that the crew of the Titan ship was still alive and deliberately making noise against frame.
But what is sonar, how does it work, and what does it mean for a rescue operation? MailOnline takes a closer look at this technology.
Every 30 minutes, a Canadian aircraft picked up a knock using underwater sonar devices called “sonic buoys” in a race against time to find five souls aboard the OceanGate submersible.
A member of the 64th Patrol Squadron of the Naval Aviation Reserve (VP-64) is shown inserting a sonar buoy into the transfer chute of a P-3 Orion aircraft during a combat exercise.
What are sonar buoys?
What is sonar?
Sonar, short for Sound Navigation and Ranging, is the use of sound waves to “see” underwater.
Sonar is used to explore and map the ocean because sound waves travel farther in water than radar and light waves.
Experts use sonar to develop navigation charts, detect underwater hazards for navigation, find and map objects on the seabed such as shipwrecks, and map the seabed itself.
As the Canadian aircraft flew over the North Atlantic search area, it dropped devices called sonar buoys, an important tool for underwater searches.
When falling from an airplane into the water, they descend to the surface of the water on parachutes.
When they reach the water, they can turn around properly at the required depth and communicate with the aircraft above.
Once in the water, the sonobuoy splits in two and the RF transmitter at one end returns to the surface.
At the other end, a group of underwater microphones called “hydrophones” is deployed, aimed into the depths of the ocean.
Both ends are connected by a cable, and any sound picked up by the hydrophones is carried along the cable to an RF transmitter that swings on the surface.
The transmitter then relays signals to the plane that dropped it, giving rescuers potentially valuable information about sounds occurring thousands of feet deep.
How does sonar work?
The way sonobuoys work is based on the principle of sonar, short for Sound Navigation and Ranging, which is the use of sound waves to locate objects underwater.
Sonar works in two different ways – active and passive detection.
A US Navy crew unloads a sonar buoy from a rack aboard a P-8A Poseidon to prepare it for use during a search mission to search for Malaysia Airlines flight MH370 April 10, 2014 in the Indian Ocean. Sonobuoys are used to detect frequencies and signals in the water.
A Canadian aircraft (file photo) heard “pops” at 30-minute intervals in the area where the submarine disappeared, the leaked memo said.
A glimmer of hope lit up a dismal search yesterday when the Coast Guard announced that ‘popping’ sounds had been detected underwater. It remains unclear if the knocking came from the submersible, but it has now become the “focus” of the mission. The picture shows the Deep Energy rescue ship – the last hope in the ongoing hunt for the ship – in the middle of the Atlantic.
Active detection involves sending a “ping” to the surrounding area and listening for the returning echo.
READ MORE: How CAN the Titan be saved at 12,500 feet?
If rescuers manage to find the missing submarine (file photo of Titan) thousands of feet below sea level, they will face a series of obstacles and an incredibly difficult search mission unlike any ever completed.
Passive detection involves listening for sounds made by propellers and machinery.
What is used here?
The search parties will mainly use passive detection – picking up noises that are expected to be the sounds of the crew hitting the hull of the submersible.
Active detection around the wreck of the Titanic is much more difficult, as it would be incredibly difficult to distinguish the submersible from the surrounding wreckage.
Another third category of sonobuoys is sometimes known as “special purpose sonobuoys” because they provide additional information about the environment, such as water temperature or wave height.
When were sonobuoys developed?
Initially, sonar buoys were developed to detect German submarines during World War II.
Any underwater acoustic signals detected by the hydrophone, caused, for example, by a nearby submarine, will then be transmitted to the aircraft via a radio transmitter.
But sonar buoys are now being used for a wide variety of purposes, including search and rescue operations.
They can display the location of an aircraft crash site, a shipwreck, or survivors at sea, and were used in 2014. during an unsuccessful search for missing Malaysia Airlines flight MH370..
The 21-foot submersible (pictured) has up to 96 hours of oxygen, but the crew of five is thought to have less than 24 hours of breathable air left as of Wednesday.
The search location is approximately 900 miles off the coast of Cape Cod, 400 miles southeast of Newfoundland, Canada. Getting there is difficult enough without finding the missing submarine below the surface of the ocean.
Now you can find a submersible?
Unfortunately, three buoys had to pick up the sound so that the experts could “triangulate” the position of the submarine.
Triangulation, commonly used by geologists to locate earthquakes, allows more precise location using angles.
How much can we hope for these noises?
Dr. Jamie Pringle, lecturer in forensic science at the University of Kiel, said: “The fact that there is a 30-minute difference between the two is a great sign.
“This is unlikely to come from another submarine, which usually only goes down to 900m, or from a surface ship propeller, which makes a continuous noise, so this sound is most likely artificial.
“Acoustic noise travels far into the water — like the sounds of whales — so this is both good news and bad news.
Timeline (British Summer Time) of the search for the Ocean Gate submersible, if the Titan loses its power, the crew will be in total darkness at 3C.
The shipwreck is at a depth of 12,500 feet. There are fears that the Titan may now be trapped inside it.
“You still need three static buoys to be able to triangulate the sound to determine position.
I should also add a caveat that the sound may of course not come from the subwoofer and not the subwoofer, let’s not give people false hope.
“Lack of oxygen is key right now — even if they find it, they still need to get to the surface and spin it off.”
Scary animation shows just how deep the missing Titanic submarine can be – a century-old shipwreck stuck on the ocean floor at 12,500 feet (TWICE deeper than the Grand Canyon).
As officials rush to rescue the five people aboard the missing Titanic underwaterexciting new video shows just how deep it can be.
clip, created by Spanish animation company MetaBallStudiosgradually descends through the digital underwater landscape.
Along the way, the heights of many landmarks are depicted in the water, including the Eiffel Tower, the Statue of Liberty and the Burj Khalifa, the tallest building in the world.
Eventually, the camera reaches a depth of 12,000 feet (3,700 meters) – the bottom of the North Atlantic, where the remains of the Titanic are located.
The Titan submersible, owned by the US firm OceanGate, began its dive on Sunday morning. all communication with his mothership was lost shortly after.