Rescuers have officially announced that the Titan submersible imploded after search robots found debris more than two miles under the ocean surface. All of the passengers aboard the missing vessel, which first lost contact on Sunday, are now believed to be dead.
The bodies of those on board -Shahzada Dawood, Suleman Dawood, Paul-Henry Nargeolet, Stockton Rush and Hamish Harding - may never be recovered. OceanGate, the company which operated the tour, made a statement on Thursday evening saying it "grieved the loss of life and joy they brought to everyone they [the passengers] knew".
Read more: The Welsh adventurer who visited Titanic shipwreck in submarine
Dr David Gallo, a senior adviser with RMS Titanic Inc, the company that owns the rights to the original underwater gravesite, said the timeline suggests something happened "mid-water" that caused them to lose power or radio communications.
But what is an implosion why did it happen? Here's everything we know following the update on Thursday:
What is an implosion?
The definition of implosion is "an instance of something collapsing violently inwards." In other words, it is a reverse explosion, it is something that explodes inwards.
In terms of the submersible, it refers to its sudden and inward collapse while under immense pressure at the depths it was diving.
Aileen Maria Marty, a former Naval officer and professor at Florida International University, told CNN how a catastrophic implosion would have been "incredibly quick", taking place within a fraction of a millisecond. She said: “The entire thing would have collapsed before the individuals inside would even realize that there was a problem. Ultimately, among the many ways in which we can pass, that’s painless.”
A video of a train imploding has been widely shared on Twitter, with many saying it is the best explanation for what happened to the submersible.
Why does a submersible implode?
Although it is unclear where or how deep the Titan was when it imploded, the Titanic wreck sits around 12,500 feet (almost 4,000 meters) below sea level. The submersible was about one hour 45 minutes into the two hour trip when it lost contact with its mothership.
According to Rick Murcar, the international training director at the National Association of Cave Divers, at the depth that the Titanic rests, pressure reaches around 5,600 pounds per square inch of pressure. This is several hundred times the pressure we experience on the surface.
Humans cannot survive that kind of pressure and therefore need a submersible. But, according to Australian robotics professor Stefan B Williams, that level of danger makes the margin of error small.
He wrote in The Conversation: "Although the Titan’s composite hull is built to withstand intense deep-sea pressures, any defect in its shape or build could compromise its integrity – in which case there’s a risk of implosion."
Similarly, chairman of the US-based Manned Underwater Vehicles Committee, William Kohnen, said the implosion of the Titan submersible was likely caused by “instability”.
Speaking to BBC Radio 4’s Today programme, Mr Kohnen said: "Clearly, something disturbed the pressure hull. If you’ve ever held a balloon and it just pops, if you just hold it lightly… something happened."
Earlier in the programme, Guillermo Sohnlein, co-founder of OceanGate Expeditions, was asked about the potential cause of the implosion. He said: "Anyone who operates in that depth of the ocean, whether it is human-rated submersibles or robotic submersibles, knows the risks of operating under such pressure and that at any given moment, on any mission, with any vessel, you run the risk of this kind of implosion."
Further, according to National World, "an implosion could occur if any part of the submersible's carbon fibre and titanium hull has suffered a small crack or fault."
"Serious safety concerns"
A former employee of OceanGatewarned of potential safety problems with the vessel as far back as 2018, the BBC reported. US court documents showed how David Lochridge, the company's Director of Marine Operations, raised concerns in an inspection report.
The report "identified numerous issues that posed serious safety concerns", according to the documents, including the way the hull had been tested. Mr Lochridge "stressed the potential danger to passengers of the Titan as the submersible reached extreme depths". He said his warnings were ignored and called a meeting with OceanGate bosses but was fired, according to the documents.
What are the effects of implosion on the human body?
The event would be catastrophic to those on board, and no one would be able to survive.
A US Coast Guard official said he could not say what the prospects were of recovering the bodies, but warned they may never be found.
Rear Admiral John Mauger said: “This is an incredibly unforgiving environment down there on the sea floor and the debris is consistent with a catastrophic implosion of the vessel. And so we’ll continue to work and continue to search the area down there, but I don’t have an answer for prospects at this time.”
The intense pressure that deep into the sea means the bodies are unlikely to be in a good condition, and finding them would be a hige challenge for rescuers. Debris from the Titan is spread out over more than a kilometre, and underwater currents could move the remains of the five men around. LBC states.
Lawrence Brennan, a professor at Fordham University’s School of Law, said specialist equipment would be required for rescuers to have a chance at finding the bodies, but that equipment is not currently at the site - but even if it was, it would only give a very slim chance of recovering them.
What was the Titan made of?
The Titan is made of carbon fiber and titanium, weighing 23,000 pounds, with safety features to monitor the structure integrity of the vessel, according to OceanGate. The material used for the submersible's body is sealed with two titanium caps to ensure the vessel was neutrally buoyant
What is the difference between a submersible and a submarine?
A submersible is different from a submarine because it has limited power reserves. This means it needs a support ship on the surface to launch and recover it. It can’t stay underwater for as long, for example the Titan typically spends 10 to 11 hours during each dive to the Titanic wreck, compared to submarines that can stay underwater for months.
How many times had the Titan been to the Titanic?
The Titan had made three previous expeditions to the Titanic wreck site, the first of which was in July 2021 - that's one a year. The recent trip isn't the first time the Titan has encountered issues which have raised concerns about the safety of the vessel.
Reporter David Pogue was onboard the vessel in 2022 when communication was lost with the mothership for two and a half hours. He later challenged Mr Rush in an interview, saying: ‘It seems like this submersible has some elements of MacGyver jerry-riggedness’.
What’s next for the search effort?
Robert Murrett joined CBS News on Thursday to talk about what could happen next in the recovery process. "In due time there will probably be recovery of as much of the debris they can find near the titanic and on the ocean floor with the remotely operated vehicles, which are already on scene."
