Barrier of depth

When it comes to talking who is to master Neptune’s possessions (as well as space), the answer is clear — both man and automaton robot. The presence of the former is necessary when working in the beneath of the oceans, so we should understand the features of the environment about which Scott Carpenter (American astronaut and ocean explorer) said: «It is more hostile than space».

The man came up with increasingly complex technical devices trying to settle in such an unusual environment for him. He started with a primitive snorkel and then armed with a leather bag filled with air, replaced by a diving bell. After that, a pump was used for supplying oxygen this was followed by waterproof suits and heavy-duty steel spacesuits.

It should be noted that the idea of such apparatus was launched one of the first in the 18th century by Yefim Nikonov. Inventor A. Khotinsky received a patent for an autonomous spacesuit in 1881. The creation of a diving school in Kronstadt a year later played a large role in the development of the depths.

The goal pursued by the brave pioneers of Neptune’s possessions remains one — to achieve a long stay in the depths and a quick return to the surface. However, in the XVIII century, the French scientist P. Baer noted: «Water pressure acts on a living organism not as a direct physical factor, but as a chemical agent». So, what’s the story?

We all breathe air in which the partial pressure of oxygen is 21278.25 Pa. But what if he will not be the same?

If the pressure is below 16212 Pa, oxygen starvation occurs, accompanied by a sudden loss of consciousness. When it exceeds 60795 Pa, oxygen poisoning occurs, followed by death.

From here it is not difficult to come to the conclusion that the deeper the submarine sinks, the less oxygen it needs. The place of which in the breathing mixture should be taken by other diluent gases. Nitrogen serves them in atmospheric air. However, nitrogen anesthesia occurs with increased pressure. Why is this happening?

Some scientists believe that the degree of the toxic effect of neutral gases depends on their solubility in water and body tissues, especially in the fat-containing substance of the brain. Others attribute this to the molecular weight of neutral gases: the larger it is, the stronger its effect. This relationship has created another version: with an increase in the density of the respiratory mixture, acceleration of its turbulence in the respiratory tract, an insufficiency of alveolar ventilation appears. And this leads to the accumulation of carbon dioxide in the body. According to the theory of Miller and Pauling, at high pressures in the cells, structural formations of water molecules form around neutral gas molecules. This changes the electrical parameters of nerve cells, which leads to macro-changes throughout the body.

But why not apply something safer? American engineer M. Nol successfully got in the water breathing helium mixture in 1937. It turned out that its using is not a cause deep intoxication even at a depth of 300 m. And then a new enemy appears. This is HPNS (High-Pressure Nervous Syndrome), which appears at great depths, where helium shows itself in the “best” way. First, the diver’s motor disturbances begin (trembling), then he can’t think clearly, becoming unreasonably excited, this ends with epilepsy. The causes of this phenomenon are explained in different ways. In some countries, scientists tried to replace helium.

Several monkeys were lowered to a depth of 600 m, giving them a helium-hydrogen-oxygen mixture, in 1968. Animals endured this experience normally. Other experiments led experts to the conclusion that hydrogen will not help to completely get rid of HPNS. Is there a maximum immersion depth of 600 m? At least you can work 300 meters below the surface. This was confirmed by divers in France and the United States, who successfully survived an eight-day stay there. Therefore, most experts believe that the limit of deep-sea diving is about 600–700 meters under the waves now.

However, there is another way to solve the problem — artificial gills. Fantastic? Yes, but recently, mechanical hearts, lungs, kidneys, and, of course, their transplantation have been fantastic.

The magazine “Technics of Youth”, 1982 — № 2