Laser Light Rummages Deep Sea Minerals

The sea floor is full of minerals: copper, manganese, gold and silver, but also of selenium, tellurium or Indium can be found there. However, it is very difficult to hide them. A laser-based autonomous system to detect samples such as nodules in the future and analyse directly on the bottom of the deep sea on their composition.

The deep sea on Earth is still largely unexplored. While there many treasures lie hidden. But in several thousand meters deep, where an extreme water pressure. No good conditions to do scientific research. A but is clear: the deep sea is an important supplier of raw materials of the future. The precious metals as deposits at hydrothermal vents are found. These are the so-called black smokers, who have a direct connection to the planet’s interior. You may occur as well as thick crusts of sulfide or be scattered as nodules at the base of the deep sea.

Previously cumbersome poking around in the deep sea fog.

It’s a cumbersome diving into the depths with remote-controlled or autonomous diving robots, which then take samples from the sea floor with gripper arms so far.

They bring her back to the surface of the water to the research ship, in whose laboratory the samples are then tested. Often nothing usable can be found and the whole expensive dive was in vain.

Analysis directly on the sea floor

Remedy is to soon a laser-based, autonomous system which is now developed by the laser Zentrum Hannover e.V. (LZH) over the next four years together with eight other European partners. The project is coordinated by the welding Institute (TWI Ltd.) in the United Kingdom. It is a combination of a diving robot and an element-analysis unit installed on board. This combined diving robot falls down on the sea floor and maps there underground.

He gives the researchers on the surface by means of cameras and measurement systems a first picture of the situation. Promising places or even objects such as nodules of diving robot can detect and determine their composition with its unit of analysis directly on-site at the sea bottom.

Laser-induced plasma spectroscopy to be used

For this, the diving robot bombarding the sample with laser pulses. With this laser-induced plasma spectroscopy (LIBS), the sample is heated so much forms a plasma at the impact point of the laser beam. This emits light from its range follows the device on board the diving robot on the contained items. This is anything but trivial. Because the system must function even under the extreme conditions of the deep sea. It must be very robust and at the same time produce a laser beam with high intensity and energy.

Deep-sea research is well comparable to space exploration

And: the instrument must be super small and super light. Deep-sea research is comparable with missions in outer space – there space and weight is a big deal in everyday life. The laser Development Department as well as material and process technology of the LZH therefore use the concentrated knowledge from the ExoMars project of the LZH for the development of the system.