Missing submersible: Rescuers race to find Titan after detecting underwater noises

Rescue teams involved in the hunt for a missing submersible that had planned to visit the wrecked Titanic said "noises" had been detected early Wednesday close to where the sub ended contact with its control ship.

Experts involved in the search say that the sub, which is carrying five people, contains an oxygen supply that may run out early Thursday morning.

Here's a guide to what we know.

What's the latest on the search efforts?

The U.S. Coast Guard said that a maritime surveillance plane operated by Canada detected the noises, which experts from the U.S. Navy are now analyzing.

U.S. authorities said various underwater search efforts had been moved to the location of the noise to discover its source, but that so far, underwater drones operated remotely had "yielded negative results."

U.S. Coast Guard Rear Adm. John Mauger said the source of the noise was still unclear.

"You have to remember that it's the wreck site of the Titanic, so there is a lot of metal and different objects in the water around the site," Mauger said in an interview with CBS News on Wednesday morning.

The U.S. Coast Guard tweeted early Wednesday that the data from the Canadian aircraft, known as a P-3 Orion, would nevertheless potentially form part of future search plans once it had been analyzed.

Experts involved in the search and with knowledge of the sub's technology say that the oxygen on board is likely to last only until early Thursday morning.

The remoteness of the location and extent of the search area — larger than Connecticut on the surface and possibly extending 2.4 miles down to the ocean floor — has complicated efforts to locate the vessel and its passengers.

"It takes time, and it takes coordination," said Coast Guard Capt. Jamie Frederick at a news conference in Boston.

Several commercial vessels have joined the effort since Sunday, including a ship that's designed to lay pipes on the ocean floor. Combined with the resources from the Canadian and U.S. Coast Guards, at least three of the vessels on site or en route are capable of deploying remotely operated diving robots.

One Canadian Coast Guard ship on the scene, the John Cabot, has side-scanning sonar capabilities, the U.S. Coast Guard said on Wednesday.

Also en route is the Canadian Ship Glace Bay, which contains a mobile decompression chamber and is staffed with medical personnel.

The design of the submersible, called Titan, means that only those outside the vessel can unseal it, so regardless of whether it rises to the surface or not, the passengers will require outside help to escape.

When and where did the sub go missing?

Titan lost contact with its support ship — a Canadian research vessel called Polar Prince — less than two hours after it first entered the water on Sunday.

At that point, it was already more than halfway down to the Titanic's wreck on the Atlantic's ocean bed, roughly 900 miles east of Cape Cod in Massachusetts.

Who was on board?

The people on board Titan include pilot Stockton Rush, the head of OceanGate, the company that developed the submersible; Paul-Henri Nargeolet, a French underwater wreck expert who has written about the Titanic and visited the wreck dozens of times; a British entrepreneur Hamish Harding; and father-son Pakistani nationals Shahzada and Suleman Dawood.

A former passenger of the Titan described it as like being in a "minivan without seats" and says the interior design relies on "off-the-shelf parts," including a video game controller for steering.

What was the sub's mission?

The missing vessel is owned by OceanGate, a company based in Washington that's become a major chronicler of the Titanic's decay.

In May, OceanGate shared the first-ever full-size digital scan of the wreck site, which is slowly succumbing to a metal-eating bacteria and at risk of disintegrating in a matter of decades.

For $250,000 a person, the company promises tourists an underwater voyage to explore the remains of the Titanic from the seafloor. From St. John's in Newfoundland, Canada, explorers travel 380 miles offshore and 2.4 miles below the surface. A full trip can take eight days and include multiple dives.

If successful, the dives offer a glimpse of what's left of the 1912 crash into an iceberg, which took the lives of all but 700 of the Titanic's 2,200 passengers and crew.

Why did the sub go missing?

It's still unclear why the submersible lost communication with its control crew on the expedition ship.

When asked for more information on Tuesday, a spokesman for the U.S. Coast Guard said that its unified search command, which includes OceanGate, is fully focused on the rescue effort.

NPR's Ayana Archie and Juliana Kim contributed reporting.

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