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Titanic submersible: What we know about the catastrophic implosion Titan sub implosion: What we know about catastrophic event
(about 16 hours later)
Watch: What debris has been found and what does it mean?Watch: What debris has been found and what does it mean?
Watch: What debris has been found and what does it mean?Watch: What debris has been found and what does it mean?
The US Coast Guard says that a debris field located in the North Atlantic suggests that a submersible missing since Sunday, with five passengers on board, suffered a "catastrophic implosion". US authorities say a debris field located in the North Atlantic leads to a conclusion that OceanGate's Titan submersible suffered a "catastrophic implosion" (a violent collapse inwards), instantly killing all five passengers on board.
The vessel, which had limited oxygen supplies, went missing deep under the ocean on Sunday after setting off to explore the wreck of the Titanic. The US Navy says it detected sounds "consistent with an implosion" shortly after the sub lost contact on Sunday during a descent to the Titanic wreck at 3,800m (12,467ft) below sea level - but this information was only made public on Thursday.
It prompted a massive five-day search and rescue operation led by US, Canadian and French agencies. The loss of the deep-water vessel was finally confirmed after a huge search mission in the area off Canada's Newfoundland island.
On Thursday evening, the Coast Guard said it had located five major pieces of the Titan amid debris around the Titanic site, which it said was "consistent with catastrophic loss of the pressure chamber". What caused the implosion?
The agency offered its condolences to the families of the victims and said it could not confirm if their bodies would ever be recovered. Titan's hull is believed to have collapsed on Sunday as a result of enormous water pressure.
The search is being wound down over the next 24 hours, although remotely operated vehicles (ROVs) will remain on site. The sub was built to withstand such pressure - and experts will now be trying to determine what exactly went wrong. Analysis of the debris may help to establish this.
Ahead of its press conference, OceanGate - the company that operates the tours - released a statement saying it believed all five passengers on board "have sadly been lost". Titan is believed to have been 3,500m below sea level when contact was lost.
"Our hearts are with these five souls and every member of their families during this tragic time," the company said. "We grieve the loss of life and joy they brought to everyone they knew." The vessel was so deep that the amount of water on it would have been equivalent to the weight of the Eiffel Tower, tens of thousands of tonnes.
Follow live for latest updates People inside are kept safe by the pressure inside the vessel.
On Thursday morning local time, two deep-water remotely operated vehicles (ROVs) arrived at the search site. A submersible attached to the Canadian vessel Horizon Arctic reached the sea floor. But if there were a rupture to the structure, the pressure outside would be much greater, compressing the vessel.
The Victor 6000, which is operated from the French research vessel Atalante, was also deployed. It had a robot that could reach the seabed 3,800m (12,500ft) down, and would have had the capacity to lift the Titan sub to the surface. What happens in an implosion?
The vehicles designed for navy submarine rescues can't get anywhere near as deep as would be needed. When a submarine hull collapses, it moves inward at about 1,500mph (2,414km/h) - that's 2,200ft (671m) per second, says Dave Corley, a former US nuclear submarine officer.
You can read more about the equipment being used in our visual guide. The time required for complete collapse is about one millisecond, or one thousandth of a second.
Authorities said earlier that the search area had been expanded to approximately twice the size of the US state of Connecticut, and a sub-surface search area of around 2.5 miles (4km) deep. A human brain responds instinctually to a stimulus at about 25 milliseconds, Mr Corley says. Human rational response - from sensing to acting - is believed to be at best 150 milliseconds.
Earlier in the search, on Tuesday and Wednesday, hopes were raised when a Canadian plane picked up underwater noises, but the US Coast Guard was unable to confirm they were from the sub. The air inside a sub has a fairly high concentration of hydrocarbon vapours.
On Wednesday the agency said that ROV operations had been relocated "in an attempt to explore the origin of the noises", but "yielded negative results". When the hull collapses, the air auto-ignites and an explosion follows the initial rapid implosion, Mr Corley says.
Who was on board? Human bodies incinerate and are turned to ash and dust instantly.
Suleman Dawood, 19, and father Shahzada Dawood, 48 How an investigation is likely to proceed?
The five people on board were: Any investigation is sure to focus on the carbon fibre mid-section of the Titan sub.
Hamish Harding, a 58-year-old British businessman and explorer The pressure vessels of deep vehicles like this are normally constructed from a robust metal such as titanium and are shaped in a sphere, to spread the immense pressure equally around the passenger compartment.
Shahzada Dawood, 48-also a British businessman -and his son, Suleman Dawood, 19 But to fit more people inside, the OceanGate sub adopted a cylindrical shape, with a carbon fibre tube inserted between to titanium end caps. Carbon fibre is very tough - they use it to build aeroplane wings and racing cars.
Paul-Henry Nargeolet, a 77-year-old French explorer nicknamed "Mr Titanic" But did that immense pressure at depth - more than 300 times the atmosphere at the sea surface - play on the material to expose flaws in the original fabrication or to introduce and then worsen instabilities over repeated dives?
Stockton Rush, 61, is the chief executive of OceanGate, the firm behind the dive Any investigation would want to know about the practice non-destructive testing.
You can read more about them all here. Aircraft are subjected to regular, very fine-scale inspections to ensure their materials are not developing cracks or that their layers are not starting to separate.
When did it go missing? Photographing the Titan debris found on the ocean floor and bringing them back to the surface for study in a forensic lab may allow engineers to identify where on the sub structural integrity was lost, initiating the catastrophic implosion.
The Polar Prince first arrived near the Titanic wreck on Sunday morning and the Titan was launched at 08:00 local time - it was expected to resurface at 15:00. Contact was lost one hour and 45 minutes into its descent, at about 09:45.
The Coast Guard said they were notified of the problem at about 17:45 - eight hours later. The agency's command centre in Boston then began coordinating search efforts.
The Titanic wreck site is approximately 600km (370 miles) off the coast of Newfoundland.
Related TopicsRelated Topics
Titanic submersible disappearanceTitanic submersible disappearance
RMS TitanicRMS Titanic
Sinking of the TitanicSinking of the Titanic
United StatesUnited States
CanadaCanada