2023-06-20 23:44:48
If the tiny submersible is found in time, rescuing the five people on board would be the deepest mission in history.
Three days have already passed since the little submarine Titan dived, on the morning of June 18, towards the wreck of the Titanic. The five passengers on board have 70 to 96 hours of oxygen. Knowing that every hour counts, the US Coast Guard is actively searching, but finding the small submersible from the private company OceanGate proves to be particularly complex. Lost in the North Atlantic, 700 kilometers south of Saint-Jean-de-Terre-Neuve, it is located in a “remote area» which comes under «challengefor research, said US Admiral John Mauger.
Missing submarine: Searches near Titanic ‘gave no results’, around 40 hours of oxygen remaining
The exceptional depth at which the Titan dived, 4000 meters to the bottom of the sea, is also a challenge. “A submarine experiences a pressure equivalent to 1kg per cm2 every 10 meters“, explains Alexis Rosenfeld. The experienced diver, who links military and civilian expeditions to the oceans, explains that the pressure at the level of the wreck of the Titanic reaches 380 bars… more than 380 kg of pressure per cm2. “I let you imagine the force exerted on the Titan“. Less than ten machines in the world – including the Nautile from Ifremer – are capable of reaching such a depth.
“80% chance he is on the ground”
Three hypotheses exist. Or the submarine has imploded, because the slightest incident, at such a depth, is fatal. In this case, the crew has no chance of having survived. Second option, he was trapped in the wreckage of the Titanic where he got stuck. Last possibility, he may have simply, because of the weather for example, lost contact with the escort ship that remained on the surface, supposed to inform him of his location. But this last hypothesis seems unlikely in the eyes of the experts, insofar as a submarine has multiple means of communication. Thus, a source at the French Navy estimates that “less than 1%“the possibility that the Titan is still between two waters, “80% that he is on the ground, and 20% on the surface without the possibility of making any contact».
«If it has sunk to the bottom of the sea and cannot come back up on its own, the options are very limited. Very few ships can go that far, and certainly not divers.“said, pessimistically, Alistair Greig, professor of marine engineering at University College London. Underwater searches by sonar are also very uncertain, because “for the sonars to work, either the device should continue to move, or it should not be embedded in the mud at the bottom, nor hidden“, explains to Figaro an engineer officer of the French Navy. “We are not immune to mapping the place where it is and to pass by”.
Either way, the US Coast Guard said it is working with military and civilian partners on a rescue plan if the vessel is found underwater. But the possible intervention options are extremely limited.
Limits of a tourist craft
When a submarine is within 180 meters of the surface, a last resort is the method of “individual statement“. The crew ejects from a watertight airlock. Each member puts on a floating suit, which allows them to float for several hours on the surface of the water while limiting the risk of hypothermia for 24 hours. The airlock fills with water at ambient pressure and, once the pressure is balanced with the outside, it is opened to allow the ascent to the surface, which is done very quickly.
Except that the Titan, a tiny tourist machine, does not have this kind of equipment specific to military aircraft. Its possible rescue equipment is not indicated on the technical sheet available on the OceanGate website. “In theory, the emergency means of this type of device is a localization buoy, which is released, rises to the surface and positions the submarine, using a very resistant cable reel.», Explains Alexis Rosenfeld.
At this point, the most credible means of rescue for the Titan seems to be, in the eyes of the experts, the bailout. The operation consists of hanging air buoys on the device to bring it to the surface, via a remotely operated robot (ROV). These robots are able to reach a very great depth. In France, for example, the Victor 6000 can go up to 6000 meters. “But we have very few industrial means capable of compressing air to pressures beyond 400 bars, as well as bringing them and using them in the area.», Explains the engineer of the French Navy, judging any salvage operation very complicated.
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Bailout, the most likely method
Other techniques exist: the ventilation method, the very first assistance technique given to a submarine in distress. Operational since 2010, it is done using an atmospheric spacesuit called NewtSuit, which operates up to 300 meters deep. “The spacesuit is piloted by a man who comes to camp air sleeves allowing to bring fresh air and to evacuate the stale air of the submarine. He is thus ventilated pending rescue“, explains Alexis Rosenfeld.
But the most complete means of rescue to date remains the NSRS device, set up by NATO after the disaster of the “Koursk“. During this tragedy on August 12, 2000, 118 sailors died at a depth of 108 meters. Since then, international coordination between France, Norway and the United Kingdom has set up the Nato Submarine Rescue System (NSRS), operational up to 600 meters deep.
The process is as follows: the submarine, prepared by a remotely operated intervention robot, joins the device in distress. It stows its own airlock to the submarine’s rescue airlock if it has one – which is the case for all military submarines. It then rises to the surface, winched onto the deck of the ship housing the entire rescue system (which must have a deck of at least 400 m²). However in the case of Titanthe use of the NSRS proves to be impossible, in particular due to the implementation time.
The deepest operation in history
«The solutions exist, but the question is rather to know: what measures, including military ones, would we be ready to implement for a group of tourists?asks Alexis Rosenfeld. The NSRS system, based in Faslane, Scotland, is air transportable, but heavy and bulky. It is theoretically deployable anywhere in the world in 72 hours, except in spaces covered with ice.
Such a rescue operation would be, by far, the maneuver carried out in the greatest depths of history. The last record dates back to 1973, when the Canadian commercial submersible Pisces III became trapped on the seabed and was recovered after 76 hours under the Celtic Sea, off Ireland. But it was only 1575 feet deep, or about 480 meters… The two people on board had been rescued 12 minutes before running out of air. “One thing is sure, concludes Alexis Rosenfeld, Paul-Henri Nargeolet(who is on board, editor’s note) is one of the best submarine experts in the world. He knows the rescue procedures very well, and no solution will be overlooked.».
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