At the end of last year, the Argentine submarine ARA San Juan lost contact with the naval base from which it left. After weeks of searching it was suspected that the worst had happened with the 44 crew members on board. Now, the Navy of that country has announced that they have just found the ship in the depths of the Atlantic Ocean.
“The Ministry of Defense and the Argentine Navy inform that on the day of the date, having investigated the point of interest No. 24 reported by Ocean Infinity, through the observation made with an ROV at 800 meters deep, positive identification has been given to Ara San Juan “, was reported on the Twitter account of the Navy on Friday night.
El #MinisterioDeDefensa y la #ArmadaArgentina informan que en el día de la fecha, habiéndose investigado el punto de interés N°24 informado por Ocean Infinity, mediante la observación realizada con un ROV a 800 mts de profundidad, se ha dado identificación positiva al #AraSanJuan
— Armada Argentina (@Armada_Arg) November 17, 2018
According to the local press, the ARA San Juan was found by the US company Ocean Infinity, 800 meters deep and about 600 kilometers from Comodoro Rivadavia, where the center of search operations was located. The company had already chosen to abandon the search, but the finding of “a point of interest” made them stay.
Now, on the last night, Ocean Infinity reported a new contact, the number 24 since the company tracked the seabed in search of the ARA. Before the signal, the ship Seabed Constructor went to the area of contact with an underwater robot, which finally was that he gave the “positive identification” of the submersible.
The sad case
In addition to the American company, other military missions from eight countries had been desperately searching for the submarine when it was known that it had cut communications. The last thing that was learned about the ship was that it had reported an electrical fault, for which reason it had been ordered from its base to return. The submarine had to travel a distance of about 2,000 km in the South Atlantic, from Ushuaia to Mar del Plata, where the naval base from which it left was located.
In regular conditions, the San Juan – in operation since 1985 – could spend 90 days without outside help, in terms of fuel, water, oil and oxygen. The submarine only needed to surface once a day, or every two or even three days, to recharge batteries and air, according to the spokesman of the Argentine Navy, Enrique Balbi and according to the newspaper El Mundo. Otherwise, the crew had seven days of oxygen.
The San Juan
The ship of 66 meters in length and 7 meters of beam had on board 44 crew members, whose last communication was given 430 kilometers from the Argentine coast of Patagonia. The Argentine Navy initially ruled out that the damage reported has had any connection with the disappearance of San Juan. The submarine, although with 32 years of antiquity (exceeding in two of its useful life), had been reconditioned with new engines and batteries five years ago. The ship could withstand a pressure of up to 600 meters deep.
The San Juan had as its main mission in the area the surveillance and the fight against illegal fishing. Being a submarine, its nature is that of a stealth ship and therefore difficult to detect. The BBC quotes Robert Farley, a professor at the University of Kentucky (USA), a specialist in the subject, to detail that it is difficult to track a submarine if it is “resting” on the seabed, it does not make any “noise”. “The noise, which would otherwise be captured by the so-called passive sonar, is distorted and [the submarine] is detected by active sonar as if it were the bottom of the sea “. That is, it goes unnoticed for a sonar.
A submarine floats when the weight of the water it displaces is equal to its own weight, creating an upward force called a floating force, as opposed to gravity (which would sink the ship). To control its buoyancy, the submarine has ballast tanks and auxiliary or compensating tanks, which it fills with water or air, depending on the movement that one wants to achieve.
When the submarine is on the surface, the ballast tanks are filled with air and the total density of the submarine is less than that of the surrounding water. As the submarine submerges, the ballast tanks are flooded with water and the air in the ballast tanks is vented from the submarine until its total density is greater than the surrounding water and the submarine begins to sink (negative buoyancy).
In order to emerge again to the surface, the submarine conserves a reserve of compressed air in tanks, not only to float again but also as life support for its crew. In regular situations, personnel on board breathe oxygen that is produced in the same boat through electrolysis plants, which process seawater and that by electricity decompose the liquid into hydrogen and oxygen.
The rarefied air
However, unlike our atmosphere (which has 78% nitrogen, only 21% oxygen, and the rest of argon and carbon dioxide), the situation in a submarine is different. While nitrogen and argon are useless, the situation with CO2 is different. This gas is a residual product of respiration, every time we exhale air, it contains 4.5% carbon dioxide and the more it concentrates, the greater the risk we are of being poisoned.
According to the National Library of Medicine of the National Institutes of Health, in high concentrations, carbon dioxide leads to an increase in respiratory rate, tachycardia, cardiac arrhythmias and problems of consciousness: “Concentrations> 10% they can cause seizures, coma and death. ” CO2 is different from carbon monoxide, the gas that, for example, comes out of the exhaust pipe of a car produced by burning fossil fuels.
Therefore, in situations such as San Juan, the crew puts into practice training focused on reducing the respiratory rate, not only to not waste oxygen but also not to contaminate with dioxide; likewise, they communicate verbally the minimum indispensable.
Thus, a submarine, to preserve a breathable environment, must: try to harvest/generate oxygen and maintain it at normal levels; remove carbon dioxide, to also maintain it in normal proportions; and remove the moisture that causes human respiration. The latter is achieved with dehumidifiers, such as those that can be purchased at a shopping center for home use. However, cleaning of dioxide is a more complicated task.
Soda lime (sodium hydroxide and calcium hydroxide) in devices called scrubbers can help in that process. Carbon dioxide is trapped in the soda lime by a chemical reaction and is removed from the air.
However, all this has a limited period of time and once the month of loss of contact has passed, the hopes of the relatives are disappearing. Now, after more than a year it is only proper to investigate what has happened.