The violent nature of the implosion, and at such extreme depths, makes any attempt to recover the vessel and its passengers even more problematic.

«There would be substantial challenges with the recovery of any body,» said Dr. Nicolai Roterman, a deep-sea ecologist at the University of Portsmouth in England. «And I think the priority right now may well be to focus on recovering as much of the debris as possible.»

At a news conference Thursday, the Coast Guard declined to answer specific questions about recovery efforts. «I don’t have an answer for prospects at this point,» Coast Guard Rear Admiral John Mauger told reporters.

Titan’s abrupt demise was apparently caused by the same deep-sea forces that make expeditions like this so rare. That’s why fewer people have been to the depths of the Titanic ocean than in space.

Anyone who has jumped to the bottom of a pool has noticed the difference in water pressure, a heaviness in the nose and ears. «Imagine that, but 1,000 times more,» White said. “That’s how it is at these depths. It’s a phenomenal force.»

In the depths of the Titanic, at about 12,500 feet down, the water pressure is nearly 400 times greater than at the ocean’s surface: some 6,000 pounds would have been pressing down on every square inch of Titan’s exterior.

«If you translate that into a physical force, it’s going to be on the order of thousands of tons to 10,000 tons, so the analogy would be the weight of the Eiffel Tower depending on what kind of loads it’s experiencing,» said Blair Thornton, professor of marine autonomy. , also at the University of Southampton, who has designed and built dozens of robot-operated deep-sea submersibles.

Roterman, of the University of Portsmouth, agreed with the Eiffel Tower analogy.

His work has taken him to depths close to Titanic in the Indian Ocean, descending to observe geothermal hot springs at around 11,400 feet on the Japanese submersible Shinkai 6500. Unlike Titan, Shinkai is owned and operated by the Japanese government, and it has been rigorously testing throughout its 1,500-odd missions.

Experts and former passengers have questioned the testing regime and safety record of Titan, which completed some 20 dives.

OceanGate Expeditions, the company that owns and operates Titan, has not responded to those criticisms this week. He did not respond to NBC News’ request for comment. But in promotional information released before the accident, he said the «state of the art craft» had been designed in collaboration with NASA and Boeing, and had undergone what he described as «incremental testing» for safety.

Like many submersibles, the Shinkai 6500 seats its crew in a titanium sphere, the manufacture of which guarantees less than 1 millimeter of deviation in its curvature. By contrast, the experimental Titan design included a carbon fiber hull and only the ends of the vessel were made of titanium, a departure from standard practice.

Although he has no direct knowledge of Titan’s design or construction, or what contributed to its failure, Thornton, the Southampton professor, said catastrophic incidents can be the result of small «flaws» in manufacturing.

«And when I say defects, I don’t mean any kind of negligent defects, just when you make things there are tiny, microscopic defects,» he said, adding that this was the only implosion he was aware of involving a manned submersible. .

When these defects are exposed to enormous forces, they can cause deformations in the structure, leading to higher stresses around those areas, Thornton explained.

«The air inside would be compressed to a point, and the forces of water rushing in and collapsing would be enormous,» he said. «Structurally,» she added, it would be equivalent to the capsule housing the crew «suddenly disappearing.»

“This whole process, from start to finish, is happening in the blink of an eye, the click of a finger,” he said. «I don’t think there would have been any suffering or any knowledge of what happened.»