Limiting Factor

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Limiting Factor
The submersible limiting factor
The submersible limiting factor
As of 2018
Ship type Deep sea submarine
Owner Caladon Oceanic LLC
Shipyard Triton Submarines LLC
Ship dimensions and crew
length
4.6 m ( Lüa )
width 1.9 m
Side height 3.7 m
 
crew 2 persons
Machine system
machine 10 electric motors with 5.5 kW each
propeller 4 main propellers
4 vertical propellers
2 maneuvering propellers
Mission data submarine
Dive time 16 hours
Immersion depth, max. 11000 m
Top
speed
submerged
3kn
Others
Classifications DNV GL

Limiting Factor is the name of the bathyscaphe that the Texan Victor Vescovo had built so that he could reach the deepest parts of all oceans. As part of the expedition The Five Deeps , it reached the bottom of the Puerto Rico Trench in the Atlantic Ocean at a depth of 8376 m on December 19, 2018 . This was followed by dives in the Southern Ocean and the Indian Ocean . Between April 28, 2019 and May 7, 2019, five dives in the Mariana Trench reached depths between 10,714 m and 10,925 m. Together with the mothership Pressure Drop and the three landers Flere, Skaff and Closp , it forms the Hadal Exploration System .

history

More than 50 years after Jacques Piccard and Don Walsh had reached one of the deepest parts of the world's oceans - the Challenger Deep - on board the Trieste , four teams tried independently of one another to build a submersible vehicle that would also be able to dive that deep.

One of the four teams was working at Triton Submarines LLC, a company based in Sebastian , Florida , on the project, which was designed using a pressure hull made of 15 cm thick glass. After James Cameron reached the bottom of the lows on March 26, 2012 with the Deepsea Challenger as the third person, the project at Triton Submarine was no longer pursued in a noteworthy manner.

In the summer of 2015, Victor Vescovo asked if they would be able to build a submersible vehicle that would allow him to dive to the deepest parts of the five oceans. He insisted that the pressure body should not be made of glass, but of titanium because he did not trust the material glass. Over the next twelve months, thought was given to the details of how the vehicle would have to be designed in order to function reliably in the deep sea, and a contract for production was signed in summer 2016. The submersible was christened Limiting Factor and tested in a submarine canyon north of the Abaco Islands in September 2018 . Several dives were made to depths of 4900 m. Employees from the classification society DNV GL were involved in the design and construction phase as well as in production and immersion tests . After successfully completing the dives in Challenger Deep, the submersible vehicle was certified for safe use in all depths of the sea and is for sale together with the mother ship Pressure Drop and the three landers for 48.2 million US dollars.

On December 14, 2018, the "Five Deeps Expedition" began to reach the deepest parts of all five oceans . On December 19, Vescoso was the first to reach the deepest point of the Atlantic in the Puerto Rico Trench at 8,326 m. In January 2019 the expedition began in the South Sandwich Trench between the southern ocean and the Atlantic. The crew mapped the trench for the first time and Victor Vescovo reached the deepest point in the Southern Ocean , which he called the “Factorian Deep”, at a depth of 7,433 m . The team then traveled to the Indian Ocean and mapped the Java Trench and the Diamantina Fracture Zone . They realized that, contrary to previous assumptions, the Java Trench was deeper and Vescoso reached a depth of 7192 m on April 11, 2019. The expedition then drove to the Pacific Ocean . Between April 28, 2019 and May 5, 2019, four dives were completed with the submersible in the Challenger Deep of the Mariana Trench . Victor Vescovo reached the new record depth of 10,928 m on April 28, 2019, and 10,927 m during another solo dive on May 1, 2019. On the third dive, also at 10,927 m, the Canadian Patrick Lahey was on board as a pilot and the German Jonathan Struwe as the representative of the classification society DNV GL . This dive served as the final proof of the operational suitability of the submersible even in the greatest possible water depth. On the fourth dive, Patrick Lahey was at the wheel of the submersible again. He was accompanied by the Englishman John Ramsey, the chief designer of the submersible. The deepest part of the Arctic Ocean was still covered by the Arctic ice cap , so the expedition mapped Tonga Trenches and Solomon Islands Trench and dived to the wreck of the RMS Titanic . Then they drove to Spitsbergen and on August 29, 2019 Vescoso reached the Molloytief , whereby the goal of the expedition was reached.

construction

Pressure body with the mounted portholes made of acrylic glass, on the left in the picture the manipulator that is not yet wired
Rendering of a section through the submersible vehicle

The shape of the hull of the Limiting Factor has been hydrodynamically optimized for a predominantly vertical direction of movement, but the submersible vehicle can also move forward with the help of ten electrically powered propellers at a speed of up to three knots and rotate around the vertical axis. Four wide-angle cameras have been installed so that the pilot has a better overview when maneuvering. The float consists of Syntactic foam - a hard foam in which many small hollow glass beads are embedded. The spherical pressure body is mounted in the float. This consists of the titanium alloy Ti-6Al-4V ELI. This quality ELI contains very small amounts of interstitial atoms ( ELI of extra low interstitials ) and is characterized due to the greatly reduced oxygen content of 0.13 percent by increased ductility and fracture toughness. The wall of the pressure hull is 90 mm thick. With an inner diameter of 1500 mm, there is space for two people. To ensure that the pressure hull will withstand the hydrostatic pressure in the deep sea, it was subjected to a pressure of 140 MPa in the DK-1000 hydraulic pressure test tank at the Krylow research center in Saint Petersburg. Next to the manhole , three large conical openings were made for the portholes made of acrylic glass (PMMA). John Ramsay, the designer of the submersible vehicle, explained that the acrylic glass is pressed into the openings at a great depth by the pressure up to 6 mm. In order to be able to take soil samples and handle objects, a hydraulically driven manipulator from the American manufacturer Kraft Telerobotics Inc. was built in , similar to the Nereus diving robot . This manipulator, valued at US $ 350,000, was lost on December 17, 2018 in a salvage after a diving attempt in the Puerto Rico trench. All electrical consumers are fed by a lithium iron phosphate accumulator , which can be thrown off in an emergency, as can the thrusters and the manipulator.

transport

The mother ship Pressure Drop in December 2018 on the Atlantic Ocean

During the Five Deeps Expedition, the submersible vehicle is transported from one diving point to another by the mothership Pressure Drop . This ship was launched on July 16, 1985 in Tacoma (Washington) and served as USNS Indomitable (T-AGOS-7) from 1985 to 2002 with the United States Navy. The ship was then rebuilt and used as the McArthur II by the National Oceanic and Atmospheric Administration as an oceanographic research ship from May 2003 to June 2014 . In 2017 the ship was bought by Caladon Oceanic LLC and converted to serve as the mother ship for the expedition.

Course of a dive

Schematic representation of the mode of operation of a fan echo sounder

First, the topology of the seabed is a multibeam recognized to be able to locate a suitable immersion point. After that, the landers are deployed , which, similar to the CTD rosette , record the change in temperature, conductivity and water pressure as they descend into the depths . Once on the ground, the landers form part of the navigation system for Limiting Factor . This pings the lander and triangulates its position from their feedback. When the work on the sea floor is finished, the ballast weight of the submersible vehicle is thrown off and it rises again to the surface. Then the landers also drop their ballast weights by remote control, emerge and, like the submersible vehicle, are rescued by the crew of the mother ship.

Trivia

Victor Vescovo's fondness for science fiction of the Scottish writer Iain Banks is expressed in the fact that he had individual components of the Hadal Exploration System named after names from the culture cycle . The deep-sea submersible Limiting Factor was named after a ship from the novel The Game Azad , and the mother ship Pressure Drop was named after the novel The Hydrogen Sonata . The Landers Flere , Skaff and Closp have shortened names of intelligent drones from Banks' novels.

literature

  • Heather Stewart, Alan Jamieson, Cassie Bongiovanni: Exploring the Deepest Points on the Planet In: Hydro International , Volume 24, No. 3, 2019, ISSN  1385-4569 , pp. 22-25 ( online as PDF ; 107 kB).
  • Craig Barnett: In Depth Knowledge: Designing, Testing, and Building the World's Most Extreme Ocean Exploration Tool In: Marine Technology Society Journal , Volume 53, No. 5, 2019, ISSN  0025-3324 , pp. 43-47 ( online as PDF ; 18.8 MB).
  • Alan J. Jamieson, John Ramsey, Patrick Lahey: Hadal manned submersible In: Sea Technology , Volume 60, No. 9, 2019, ISSN  0093-3651 , pp. 22-24 ( online as PDF ; 6.1 MB).
  • Josh Young: Expedition Deep Ocean: The First Descent to the Bottom of All Five Oceans . Pegasus Books, 2020, ISBN 978-1643136769 .

Individual evidence

  1. a b Online article from the US American magazine Popular Science about diving in the Puerto Rico Trench , accessed on December 23, 2018.
  2. Victor Vescovo makes deepest submarine dive in history , accessed on May 1, 2020.
  3. a b c d e website for the Hadal Exploration System of the submersible boat manufacturer Triton Submarines LLC , accessed on December 10, 2018.
  4. a b c d e Frequently Asked Questions (FAQ) from the Five Deeps Expedition.com website , accessed on December 10, 2018.
  5. Online article from the BBC Race to the bottom of the ocean , accessed December 23, 2018.
  6. Online article from the BBC Race to the bottom of the ocean: Triton , accessed December 23, 2018.
  7. a b c Humans are about to touch the deepest corners of the ocean for the first time - an endeavor as dangerous as landing on the moon , accessed on December 21, 2018.
  8. a b c Ben Taub, Paolo Pellegrin: Thirty-six Thousand Feet Under the Sea: The explorers who set one of the last meaningful records on earth . In: The New Yorker , May 10, 2020.
  9. FAQ , fivedeeps.com, accessed May 12, 2020.
  10. Francesca Street CNN: Deepest ever manned dive finds 'plastic bag'. May 13, 2019, accessed November 12, 2019 .
  11. Material data sheet for the titanium alloy Ti-6Al-4V ELI Grade 23 (PDF; 784 kB)
  12. Information on the pressure test tanks of the Krylow Institute Complex of Hydraulic Pressure Test Tanks , accessed on January 12, 2019.
  13. Data sheet for the Raptor manipulator from the manufacturer Kraft Telerobotics (PDF; 1.34 MB), accessed on December 23, 2018
  14. Extract from the United States Navy Ship Register , accessed December 23, 2018.
  15. Excerpt from the National Oceanic and Atmospheric Administration's ship register , accessed on December 23, 2018.
  16. more information about the ship on the website of the Five Deeps Expedition , accessed on December 23, 2018.
  17. Information on the multibeam echo sounder on the website of the Five Deeps Expedition , accessed on December 23, 2018.
  18. Data sheet for the EM124 multibeam echo sounder from the manufacturer Kongsberg (PDF; 1.19 MB), accessed on May 15, 2019.
  19. Information about the countries on the website of the Five Deeps Expedition , accessed on December 23, 2018.
  20. Details on technical solutions in the article in The Engineer magazine , accessed on March 27, 2019.
  21. What's in a name? ( English ) The Five Deeps Expedition. Retrieved July 9, 2020.

Web links

Commons : Limiting Factor (submersible)  - collection of images, videos and audio files
Commons : DSSV Pressure Drop (ship, 1985)  - Collection of pictures, videos and audio files