Mariana Trench

You have been asked to prepare an outline design for the pressure hull of a deep-sea submersible vehicle capable of descending to the bottom of the Mariana Trench in the Pacific Ocean. The external pressure at this depth is approximately 100 MPa, and the design pressure is to be taken as 200 MPa. The pressure hull is to have the form of a thin-walled sphere with a specified radius r of 1 m and a uniform thickness t. The sphere can fail in one of two ways ... 

Takai K, Inoue A, Horikoshi K. 1999. Thermaerobacter marianensis gen. nov., sp. nov., an aerobic extremely thermophilic marine bacterium from the 11000m deep Mariana Trench. Int J Syst Bacteriol 49 619-28. 

There are several types of environments on Earth where significant water exists at prevalent low temperatures such that ice and liquid aqueous solutions commonly coexist permafrost, snow, glaciers, lake and river ice, sea ice, and parts of the atmosphere (polar troposphere, global upper troposphere, and stratosphere). In addition, the deep sea floor occurs at temperatures very close to the freezing point of water. For example, temperatures in the oceanic abysses hover around 2°C at a maximum hydrostatic pressure of 1100 bars (10,660 m) in the Mariana Trench (Yayanos, 1995). Table 4.1 summarizes some of these environments. Furthermore, in some permafrost and sea-floor environments, the presence of nonpolar gases under pressure can stabilize a modified form of ice known as gas hydrates even where temperatures are not quite low enough for ordinary ice to form. 

Kato C, Li L, Nogi Y, Nakamura Y, Tamaoka J, and Horikoshi K (1998) Extremely barophilic bacteria isolated from the Mariana Trench, Challenger Deep, at a depth of 11,000 meters. Appl Environ Microbiol 64 1510-1513 Kaye JZ, Baross JA (2000) High incidence of halotolerant bacteria in Pacific hydrothermal-vent and pelagic environments. FEMS Microbiology Ecol 32 249-260... 

Kato, C. (1999). Molecular analyses of the sediment and isolation of extreme barophiles from the deepest Mariana Trench. In Extremophiles in Deep-sea Environments, ed. 

Takami, H., loue. A., Fuji, F. Horikoshi, K. (1997). Microbial flora in the deepest sea mud of the Mariana Trench. FEMS Microbiology Letters, 152, 279-85. 

Bloomer S. H. and Hawkins J. W. (1987) Petrology and geochemistry of boninite series volcanic rocks from the Mariana trench. Contrib. Mineral. Petrol. 97, 361-377. 

Trenches are long, narrow, canyon-like structures, most often found adjacent to a continental margin. They occur much more commonly in the Pacific than in any of the other oceans. The deepest trench on Earth is the Marianas trench, which runs from the coast of Japan south and then west toward the Philippine Islands. Its deepest spot is 36,152 ft (11,022 m) below sea level and it runs a distance of about 1,580 mi (2,550 km). The longest trench is located along the coast of Peru and Chile. Its total length is 3,700 mi (5,900 km) and it has a maximum depth of 26,420 ft (8,055 m). 

The deepest point in the oceans of the world is believed to be in the Marianas Trench, southeast of Japan there the depth is about 11,000 m. What is the pressure at that point ... 

Sampling of the sea mud from the Challenger Deep of the MARIANA trench... 

In a television broadcast [18] it was reported that at the bottom of the Mariana Trench, the deepest part of the world s oceans with a depth of 11000 m, the temperature is —2 which is below the well-known melting point of 0°C. Check whether this is plausible or not. The differences in the properties between pure water and sea water shall be neglected. For the liquid density of water, = 1000 kg/m shall be used. The pressure is... 

This means that the melting point decreases by almost 10 K due to the elevated pressure therefore, the temperature of i = —2 C at the bottom of the Mariana Trench is possible. Due to the salts dissolved in the sea water, the melting point is further lowered (cryoscopic constant. Section 8.1.1.1), but the main effect is caused by the pressure elevation in this case. 

Development of remotely operated vehicles, greatly expanded since the 1980 s, has made it possible to penetrate ocean depths that were unreachable by manned undersea devices. In May, 2009, the Woods Hole Oceanographic Institution used a remotely operated vehicle called the Nereus to revisit the depths of the Mariana Trench, which had been partially explored by a Japanese remotely operated vehicle in 1998. The small dimensions of the Nereus (8 feet wide and 14 feet long) enabled it to maneuver in tight spaces, and the vehicle combined several advanced technologies, most notably a remarkably thin fiber-optic tether. 

This process is exemplified by the examination of a billiard ball, a hard and extremely smooth spherical object. If one could expand the scale of the billiard ball to the size of the planet, maintaining the surfece irregularities to scale, then the surface of the billiard ball would be covered with bumps and ridges higher than Mount Everest and depressions deeper than the Mariana Trench. In simplest of terms, friction results from the binding of the irregularities of one surfece in those of another. 

If it were expanded to the size of the planet, the surface of a glass-smooth billiard ball, for example, would have peaks higher than Mount Everest and valleys deeper than the Mariana Trench. Images from scanning probe microscopes demonstrate that no surface is perfectly flat, but that all surfaces are made up of bumps and holes, like a layer of golf balls in a box. 

Yardney battery still holds the distinction of going deeper than any manned submersible with the U.S. Navy s Trieste to the bottom of the Marianas Trench using our 1000 and 5000 Ah silver zinc batteries. For many years Yardney s 12 Ah battery was used by virtually every major television network for their portable cameras. Overseas, Yardney s 16 Ah silver cadmium batteries were used by the various prime contractors which included an Italian company for the successful GIOTTO mission that monitored the passage of Halley s Comet past Earth in 1986. 

Examples of barophUes include Moritella and Shewanella species that laboratory experiments suggest can grow at 70 MPa, but not at pressures of 50 MPa [28], suggesting they are true barophiles. Similar bacteria have been obtained from the Mariana Trench. More remarkable evidence has been presented for growth using a diamond anvil apparatus. Shewanella oneidensis and Escherichia coli were reported to remain physiologically active at pressures up to 1,680 MPa for up to 30 h [29]. As for low temperatures, the pressure limits for life remain unknown. 

Dermacoccus abyssi (MTl.l, MT1.2) Sediment (—10 920 m) Mariana Trench Dermacozines A-C (phenazines) Cytotoxic radical scavengers Abdel-Mageed etof,2010... 

Abdel-Mageed, W.M., Milne, B.F., Wagner, M., Schumacher, M., Sandor, P., Pathom-aree, W., Goodfellow, M., Bull, A.T., Horikoshi, K., Ebel, R., Diederich, M., Fiedler, Fi.-P., and Jaspars, M. (2010) Dermacozines, a new phenazine family from deep-sea dermacocci isolated from a Mariana Trench sediment. Org. Biomol. Chem., 8, 2352-2362. 

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