Hyperbaric Marine Habitat Construction

ABSTRACT

Underwater habitats are structures in the water that allow humans to live for extended amounts of time while being active. An underwater habitat has to meet the needs of human physiology and provide a livable human condition, and some of the most critical are breathable air, the right pressure, temperature, light, humidity, drinking water, food, and where to put human defecation. There are many reasons scientist attempt to live underwater. One reason scientist would live underwater is to find more livable space for the public, as the sea levels and the world populations grow, we will soon run out of space on land, so some scientist believes that we should begin to colonize the oceans. A French architect by the name of Jacques Rougerie has designed many livable underwater habitats over his career. In a boatyard in Bordeaux he created the first step to his latest creation: SeaOrbiter, a SeaOrbiter is a floating colony for researchers that is around 31m beneath the surface. Also, Canadian scientist Phil Nuytten is attempting to develop a colony which extends deeper underwater, this farms purpose would be to gather resources from thermal vents.

Scientists have been living underwater in controlled habitats since 1962. The first one; called Conshelf 1, was made by Jacques-Yves Cousteau. Constructed of a steel cylinder, the habitat was home to two divers for a week at Marseilles at a depth of 10m. Their day consisted of monitoring marine life and building a farm. That was not the end, in 1970 an all-female team of US aquanauts spent over 10 days 15m underwater in the Caribbean. Since then scientists have continued to live underwater, but this asks the question, why? To answer that first we must explain what underwater habitats are.

The scientist also make ensure there are no hazardous sea creatures such as microorganisms, marine fungi, and more. Many underwater habitats have been created since 1962, but not all are government, many are privately owned, they are almost exclusively used for research purposes, but lately, some have been made for lavish getaways. There are four different types of habitats. One the floating habitat, which is in an underwater floating structure around a depth of 30m, the advantage of this is horizontal mobility. Two, the access shaft to the surface, this habitat is accessible from a shaft to above the water surface, this limits the depth of submersion, but it almost has a more normal atmospheric pressure and can be maintained inside so that visitors can come and go without any decompression. This is generally used close to shore, an example is the restaurant Ithaa in the Maldives or Red Sea Star in Eilat, Israel. Third, the semi-autonomous habitat, this habitat is accessible only by diving, energy and oxygen is supplied by a cable, most research habitats are of this type, examples are Aquarius, SEALAB I and II and Helgoland. Lastly fourth, the autonomous habitat, this station has its own saved energy and oxygen and is able to move around on its own in a vertical direction, it is very similar to submarines.

There are many risks to living in an underwater habitat. On June 1st, 2014, Fabien Cousteau and his team of aquanauts went to live in an underwater habitat, they are photographers, scientists from Northeastern and MIT specializing in marine biology and underwater engineers. Their mission was to experience the challenge of living underwater for over a month in a pressurized saturated environment. Saturated diving is a type of diving which allows the body to gradually absorb inert gases by staying at depth for a long period of time. The gases usually would be a threat to a standard scuba diver by expanding like the bubbles in a shaken bottle of soda when the diver returns to the surface, causing pain, paralysis, and sometimes death. This is also known as bends. The divers are trying to stay underwater for 6-8 hours without bends interfering, the usual diver goes underwater for around an hour before being threatened with bends. To make sure the divers are not plagued with bends at the end of the mission, their entire environment is slowly brought back to normal pressure so that the gases can escape the diver’s bodies safely, so the divers are free to resurface. Another great risk which is also the most common is called the “creeping crud.” This can be anything from acne to rashes to diaper rash, its caused by divers that urinate in their wetsuits, which is unavoidable due to the amount of time the divers are underwater for. Toward this off divers are told to shower when done diving with antibacterial soap and dried with fresh towels. Ear infections are also extremely common to divers but have an effective treatment that includes aluminum, divers even claim their infections and wounds heal faster in the water due to the pressure, although this is unproven. Divers also explain that during their time in the habitat their sense of taste diminishes due to the higher density of air in the habitat, meaning that there are fewer parts per million of food odors diffused in the air for the nose to detect. Divers tackle this with hot sauce. Also, the extended dive time and pressure takes heat from divers much more rapidly than it would on the surface, and so their metabolisms must work harder to maintain body temperatures, this causes divers to get hungrier faster. Also, the air density causes voices to become higher pitched which either adjusts with time or the ears of their comrades adjust.

Scientists stay underwater in habitats doing lots of studies, but there is one that stands out, bends. Scientists stay under for weeks studying ways to change bends and how it affects our bodies, but what exactly is bends and how does it work? When people go deep sea diving, they usually take an air tank with them to breathe, this is normally transported within highly pressurized air tanks. Our bodies built to handle pressurized air of that caliber. With higher air pressure our blood dissolves, meaning he pressurized air dissolves into the bloodstream easily, including helium, nitrogen, and oxygen. When divers want to emerge back to the surface, they must be sure they do not do this too quickly or they will have the risk of creating numerous bubbles from blood-soluble gases. When nitrogen gas forms bubbles, it accumulates and fills our muscles and blood, causing pain and possibly death. The best way to avoid bends is the following, ascending to the surface at a rate of 60 ft/min roughly, visiting a decompression chamber which will slowly reduce the high pressure, and breathing in compressed air mixture of helium and oxygen since helium is not as absorbent to our muscles.

Saturation diving is an important part of deep sea diving since it helps reduce chances of bends, these saturation divers typically breathe a helium-oxygen blend to prevent nitrogen narcosis which causes the diver to lose their senses and motor skills. Saturation divers live in a pressurized environment, this can be in a surface or underwater. This system decompresses the body in a closed pressurized area and can take up to several weeks. The history of saturation diving goes back to 1938 when Edgar End and Max Nohl made the first intentional saturation dive, which lasted 27 hours in a 101-foot sea level. Their decompression after the dive lasted 5 hours and the scientist had mild decompression sickness that was resolved with recompression. Albert R. Behnke originally had the idea of exposing humans to high ambient pressures for an extended amount of time to allow their blood and tissues to become soaked with inert gases in 1942. Later in 1957, a scientist by the name of George F. Bond started to develop the Genesis project in the Naval Submarine Medical Research Laboratory and proved that a human can last a long amount of time underwater with different blends of oxygen gases and high environmental pressures. Once the tissues and muscles of the saturation diver are saturated, the time needed to decompress is dependant on the depth and gases that were intaken. This was the first strive for saturation diving and the US Navy’s Man-in-the-Sea Program, and commercial saturation dives started in 1965 by Westinghouse in an attempt to replace broken trash racks at 200 feet at Smith Mountain Dam. Peter B. Bennett is the inventor of the trimix breathing gas which is a method that is supposed to stop high-pressure nervous syndrome. In 1981 an experiment at the Duke University Medical Center called Atlantis III, had volunteers get to a pressure equal to a depth of 686m in seawater (2250 few), and then decompress slowly to atmospheric pressure around a 31 day period. Later in the experiment, a scientist by the name of, Atlantis IV, found a problem when one of the volunteers experienced euphoric hallucinations and hypomania. There are many effects of saturation diving, one of the biggest is bends which were referenced earlier. Another effect is high-pressure nervous syndrome (HPNS), this is a neurological and physiological diving sickness that occurs when saturation divers go below 500 feet while using a helium-oxygen blend tank. The symptoms are dependent on the speed of descending. HPNS is limiting how far scientists can go when deep sea diving, but can be reduced when adding small amounts of nitrogen in the divers gas tank. Saturation diving can also cause aseptic bone necrosis, which is caused when blood is not efficiently going to tissue causing it to die. Joints are usually the most likely to get affected but it is not yet fully understood what causes this. Scientists also now breathe a gas mixture of oxygen, helium, and hydrogen which was developed to reduce the effects of high pressure on the central nervous system at deep sea levels. In 1981, when a depth test at 686 meters, the scientist concluded that the generic mixture of oxygen and helium was completely unsafe when volunteers to a study started to struggle and caused them to suffer trembling and memory loss. Research also started to pop up that provides evidence to long term reduction of lung health for saturation divers. Saturation divers also get infections which include skin rashes, otitis externa, and athlete’s foot.

In the future scientists want humans to be able to build livable cities to expand the livable space in our world. According to Ian Koblick, an underwater habitat designer, today’s technology allows is sufficient enough to create habitats that can support a maximum of 100 people if we use the habitats we have today as blueprints, but if more funding was available it is more then possible to be able to create habitats that can support more, the only technology missing would be emergency evacuation, and environmental controls of air supply and humidity. Another challenge would be energy independence, which in theory can be solved with solar panels on the surface. Koblick also explains that rather than making a risky bubble that requires advanced technology, we can simply make larger habitats with multiple modules made of steel, glass and special cement used underwater. To be safe, it would also be wise to not go above 1,000ft, since the pressures at a depth that great would bring the need for thick walls and constant decompression when returning to the surface. The only factor stopping humans from colonizing the ocean is lack and interest and funding, but a Polish company named Deep Ocean Technology believes commercializing underwater habitats to allow tourists to experience living underwater could help change the lack of interest, the company already has agreements with architects and builders to design a Water Discus Hotel at the Noonu Atoll, Kuredhivaru Island in the Maldives within the next three years. Dubai, Singapore, and more than one European nation also started discussing the idea of building these commercial underwater habitats.

SOURCES:

• https://www.sciencefocus.com/planet-earth/could-humans-live-in-underwater-cities/
• http://www.bbc.com/future/story/20130930-can-we-build-underwater-cities
• https://en.wikipedia.org/wiki/Underwater_habitat
• https://www.popsci.com/article/science/what-happens-human-who-spends-month-under-sea
• https://en.wikipedia.org/wiki/Saturation_diving