Underwater missions at a depth of 5,000 meters

Engineering | innovation | Extreme conditions below sea level make it almost impossible to perform research on the seabed. The Modifiable Underwater Mothership, an unmanned underwater vehicle, could now permanently change the way underwater research is conducted. Also affectionately called MUM, it's supposed to dive up to 5,000 meters into the depths of the ocean. Down there the underwater vehicles can help researchers enormously – in very different ways.

Extreme conditions below sea level make it almost impossible to perform research on the seabed. The Modifiable Underwater Mothership, an unmanned underwater vehicle, could permanently change the way underwater research is conducted. Also affectionately called MUM, it’s supposed to dive up to 5,000 meters into the depths of the ocean. Down there, the underwater vehicles can help researchers enormously – in very different ways.

Two thirds of our planet’s surface are water blue. Seven seas and three oceans separate countries and continents. These waters have always fascinated mankind, especially because large parts of the seabed are completely unexplored and mysterious. The harsh weather conditions on the surface make research at depth extremely difficult.

That is why our engineers have teamed up with researchers from the TU Berlin and the University of Rostock, as well as with engineers from EvoLogics. Their goal: develop a new class of unmanned underwater vehicles to make work on the bottom of the world’s oceans possible.

The project is called Large Modifiable Underwater Mothership (MUM). For three years, until 2020, it will be funded by the Federal Ministry of Economics and Energy. “We want to create a modular product family,” says Hendrik Wehner, who co-supervises the project at thyssenkrupp in Kiel. “The goal is an underwater vehicle made of various modules that can be changed depending on the type and location of use.”

MUM: An important colleague under water

And, in fact, we need help at sea. Nobody dares to go down to depths of more than 200 meters – the health risks for the human brain are simply too high. Working in diving bells, via robot arms and cameras, however, does not offer the necessary flexibility.

In addition to enormous pressures under water, the conditions on the sea surface also make the work of the researchers more difficult. “Missions above-water are often not possible or only possible to a limited extent, due to harsh environmental conditions on the sea surface. In many cases, underwater vehicles are the better choice for maintenance or installation,” says Wehner.

Our engineers and their partners have analyzed more than 40 application areas. Finally, they selected three of them as the basis for the development of the MUM modules.

In order to produce maps of the underwater world, the MUM must be able to set down and resume seismic sensors at great depths. The underwater vehicle can also be used in oil and gas production. Drill sites must be serviced regularly. However, the valves of the wells are often located at depths of up to 3,000 meters and more than 100 kilometers from the production platforms. If one of the underwater control modules, Subsea Control Modules, breaks, the costs can quickly go into the millions. “This is an exciting application for a MUM because the SCMs are very heavy and are located relatively close to the sensitive drilling rigs,” Wehner explains.

Underwater vehicles can help researchers enormously - in very different ways.

Deep sea mining is another conceivable field of application for the MUM. The seabed contains cobalt crusts, manganese nodules and metalliferous sulphur compounds in rough quantities of copper, zinc, gold and silver. Germany already holds a deep-sea production license in the North-East Pacific. The corresponding conveying technology only has room in large overseas containers and must be towed precisely to the seabed. “We would like to use MUM for these transport tasks,” says Wehner.

Modular construction for underwater vehicles

But our engineers and partners do not have to reinvent the wheel. Cable-guided underwater vehicles have actually existed for many years. Autonomous underwater vehicles have also been in use for some time.

So what makes the MUM so special? “Classic underwater vehicles are designed for a specific task,” explains project engineer Pia Haselberger. Thus, the MUM differs from existing models due to its modular design and fuel cell drive. “We want to develop individual basic modules for basic capabilities such as propulsion and energy supply, which together with special mission modules, extend the functional scope of the MUM as required,” says the engineer.

At about four knots, which corresponds approximately to walking speed, the vehicle will dive into the depths of the ocean after completion. Thanks to its fuel cell, it will be able operate for several weeks without interruption at depths of up to 5,000 meters. The fuel cell must function autonomously over a long period of time and within a range of over 1,000 kilometers. Therefore different, pressure bodies are necessary for different ambient pressures.

Underwater vehicles and their development: many clever minds come together

The distribution of tasks between engineers and scientists enables all partners to contribute their expertise. The researchers at the University of Rostock are developing a control system that is adapted to the variable vehicle structure and are collecting the necessary measurement data in various diving experiments to determine the parameters for the motion model and the depth regulator.

Just a few kilometers further north, at thyssenkrupp in Kiel, six of our machine and shipbuilders are responsible for the technical design of the vehicle and drive system and bring together the developments of all partners in various designs. Some colleagues in Bremen are also working on solutions for the guidance and navigation system of the vehicle.

Three researchers at the TU Berlin design propeller drives for high positioning accuracy and build a model to test MUM variants. EvoLogics from Berlin is at home in underwater communication technology and develops the telemetry network of the system.

“I don’t know if we can do everything we have planned – because the project is quite visionary,” says project manager Marc Schiemann. “But we have a fantastic team!” A true-to-scale model in a ratio of 1:5 is to withstand initial tests by 2019. Three years later, the first prototypes could already explore the oceans. And in just ten years, the first MUMs could set off for the dark world of the deep sea.

Well written article. It’s a lot of fun to work on this project as you might imagine reading this 🙂

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