The final moments of the Titan would have been swift – and unleashed amid a force difficult to comprehend.
A North Atlantic rescue mission undertaken by at least four countries found that the submersible was destroyed by a likely implosion, scattering its debris on the ocean floor near the doomed luxury liner Titanic. Parts of the sub were found about 1,600 feet from the Titanic, nearly 12,500 feet below the surface in icy, dark waters.
It will be difficult to know at what depth the Titan sub became overwhelmed. But even at higher depths than where it was found, any defect in the hull would have allowed the Titan to be crushed in milliseconds, experts in physics and submarines told USA TODAY Thursday.
Stockton Rush, owner and founder of OceanGate Expeditions, was piloting the Titan with a group of four passengers when the submersible lost contact Sunday with its support ship about an hour and forty-five minutes after starting its dive.
“The pressure inward on the sub would have been enormous,” said Luc Wille, a professor and chair of physics at Florida Atlantic University. That likely explains what appears to have been the implosion of the vessel, said Wille and others.
News outlets reported Thursday that Navy sonar equipment detected an undersea explosion in the area around the time the Titan lost contact.
While the experts grieve the loss of the Titan and its passengers, they describe extreme and unforgiving conditions at the depth where two wrecks now lie some 2.5 miles below the ocean’s surface. They say it will be crucial to the families and future ocean exploration to learn as much as possible about what caused the implosion that claimed five lives.
Killed in the incident were Rush, Pakistani businessman Shahzada Dawood and his son Suleman, French explorer Paul-Henry Nargeolet and British explorer Hamish Harding.
How intense is the pressure at the depth of the Titanic?
Nearly 380 times greater than at the surface, Wille said.
It’s a familiar concept to divers, who feel the pressure on their bodies as they descend and must regulate the air they’re breathing accordingly. Wille said the rule of thumb is one additional “atmosphere” of pressure for every 30 feet of water.
“People always underestimate that impact,” Wille said. Because water is so much more dense than air, “pressure builds up much faster than it would when we’re going up or down in the atmosphere.”
The diver with the deepest dive ever recorded reached 1,090 feet. The remains of the Titanic are 12,500 feet deep. Experts say the pressure at that depth is between 370-380 bars.
Think of the pressure at the center of the most intense Atlantic hurricanes, which are essentially huge low pressure systems. Hurricane Wilma – the most intense Atlantic hurricane on record – had a pressure of 882 bars.
Wille compared the pressure on the Titan to a classic physics demonstration. If you remove all the oil or water from a sealed metal can, it will collapse under the pressure of just one atmosphere of pressure at sea level, Wille said. “Just imagine what several hundred atmospheres (of pressure) will do.”
“The pressure inward on the sub would have been enormous,” he said.
What is an implosion?
The opposite of an explosion. Rather than pressure building on the inside and causing something to explode, the ocean generates incredible pressure on the outside of a vessel, collapsing walls inward.
How could intense pressure cause the submersible to implode?
Experts who did not have direct knowledge of what happened to the Titan told USA TODAY it sounds like the hull gave way, either due to a structural defect or failure, or fatigue of the materials in the hull. Even the slightest defect in the hull could have made the Titan vulnerable.
When you repeatedly pressurize material such as the walls of the sub, “you’re stressing it out,” Wille said. “You’re squeezing the atoms that make up the material, putting that material under stress and then letting it go.”
Metal fatigue is the reason you can work the flip top of a soda can back and forth to pop it off, he said.
Even high-grade military submarines don’t wander around the ocean at full depth because it’s just too dangerous, said Eric Fusil, a submarine expert and associate professor in the University of Adelaide’s School of Electrical and Mechanical Engineering.
It would take something like “20 milliseconds to crush a hull” at the depths the Titan was operating in, Fusil said. “So it’s nearly instantaneous and it’s absolutely very, very noisy.”
Although the Titan’s composite hull is built to withstand intense deep-sea pressures, any defect in its shape or build would compromise its integrity and increase the risk of implosion, said Professor Stefan Williams, a marine robotics and underwater vessel expert at the University of Sydney.
Did anyone hear a “catastrophic implosion?”
Not that they’ve admitted publicly yet.
But, the Navy detected an “anomaly” consistent with an implosion or explosion in the vicinity when it went back and analyzed its acoustic data after the submersible was reported missing Sunday, a senior Navy official told The Associated Press, speaking on condition of anonymity. The Navy shared the information with the Coast Guard, but the data was not considered definitive.
Listening devices weren’t deployed in buoys at the site until after the Coast Guard arrived, but that would have been too late to pick up an implosion if it occurred during the Titan’s descent or shortly after.
The Titan was only about 21 feet long, but any implosion would have created a very loud sound that would have traveled through the water and might also have been picked up by an ocean seismometer somewhere, Fusil said.
When the Navy completed ship shock trials of a vessel with 10,000 pounds of explosives in the Atlantic off Florida in July 2016, the U.S. Geological Survey detected that explosion at the surface. A search of its public database shows the Survey’s seismometer network had not registered any earthquake-like explosions in the North Atlantic over the last week.
Have other vessels imploded?
Yes. In 1963, the USS Thresher, a nuclear-powered submarine, was conducting deep-diving tests around 220 miles east of Cape Cod when it lost power and imploded, taking the lives of 129 sailors and civilian technicians. Its remains were located about 8,400 feet below the surface, and a Court of Inquiry concluded the sub likely sank due to a piping failure and subsequent loss of power and the inability to blow ballast tanks fast enough to avoid sinking.
Why is it important to know what happened?
The engineering and regulation of deep-sea submersibles remain somewhat uncharted territory, Fusil said. And because the Titan was operating in international waters, it was “technically free from governance by any single nation’s regulations.”
Although various professional groups have proposed rules for commercial sub design, following those rules remains voluntary, and dependent on what insurance companies require, Fusil said. “It’s time to acknowledge that going deep is as complex, if not more complex, than going into space – and that ensuring the safety of submersibles ought to be more than a matter of choice.”
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