Day 8
07 february 2022
Bacterial colonizers
Iron is an essential element to life and naturally present in the environment. Céline is interested in its oxidation by bacteria in the ocean depths.
The oxidation of iron is a natural reaction that allows the bacteria to provide themselves with energy. It works as follows: oxygen atoms pull out electrons from iron atoms, which generates energy. It's the same principle as in a battery: the flow of electrons produces electricity, and this is how these so-called iron-oxidizing bacteria bacteria work.
The oxidation of iron transforms it into another type of iron, this is the process of rust formation, and the same thing happens in the bottom.
On the picture, we see the colonizers prepared by Céline which will be used to host bacteria living at 2400m. Each tube is a small living environment made to measure for them! Some contain plastic of different compositions, others iron of different origins.
Colleagues of hers would like to understand the degradation of plastics by microorganisms and by the seawater. They will also identify the species that are responsible.
Céline studies iron, and she has chosen to use two different types. One of synthetic origin: iron shot; and the other of natural origin: basalt glass. Basalt is a magmatic rock. In the case of an underwater volcanic eruption, the magma undergoes an extremely rapid cooling that transforms it into glass, this is why it's called basaltic glass. It's glass, but very rich in iron. Simply, here, it has been manufactured in laboratory to reproduce the basaltic glass coming from the volcanic activity of the funds. The colonizers will thus make it possible to study the activity of oxidation of these two types of iron by the bacteria.
We can study the bacteria thanks to iron, and we can do the opposite by studying the iron thanks to bacteria! Depending on the iron-oxidizing bacteria identified in the sea floor, scientists can determine the type of iron associated with it and follow its evolution in the oceans. These studies also aim to understand the impact of global warming on the micro-organisms of the ocean floor.
Going down?
The weather forecast calls for a return to calm tomorrow! The Nautile should therefore be ready to dive at 9:00 am! It will be sent to the bottom with a scientist and two pilots to verify and adjust the positions of the devices on the bottom.
In the meantime, we would like to take you on a tour of this submarine, which is designed for exploration and intervention at depths of up to 6000 m. As a reminder, the living area is a 2m² sphere equipped with a rebreather system that allows to maintain a normal oxygen level and to eliminate the carbon dioxide rejected. The air passes through granules of soda lime which removes the carbon dioxide, this is called a re-breathing circuit or circular circuit.
The entrance is located on the top of the Nautile, and to access it, you must climb to the upper floor of the hangar. Here is the hole through which you have to sneak down!
In the Nautile
Here we are now in the habitable sphere. It's a little cramped but we quickly feel good inside! There are 3 small windows for the 3 passengers (pilot, co-pilot and scientist). Their small size results from a compromise between the thickness of the glass and the size of the observation window. To resist to the pressure of 6000m depth is equivalent to undergo 600kg force per cm², so the glass must be solid! A larger window would require a way much thicker glass.
On the sides, the sphere is lined with buttons, electronics and equipment. It's therefore better to be careful with your movements and to keep your position. The two hassocks on either side allow passengers to lie down facing the window to observe the landscape when maneuvers allow it! Rather nice, isn't it?
Guillaume is one of the co-pilots and he is also the Nautile's electronics technician. During the dives, he is in charge of the Nautile's atmospheric management, the positioning of the devices, the contact with the surface and the taking of images. For safety reasons, the Nautile must communicate with the surface every 30 minutes.
Also responsible of the controls of the Nautile are Olivier, co-pilot, Julien, pilot and technical manager, and Frank, pilot and chief of operations. They take turns to ensure the Nautile's numerous dives. Rest and concentration are paramount.
Performing the immersion, steering and recovery of the Nautile mobilize navigators, mechanics, and divers. We will show you their involvement in tomorrow's dive!
Crédit photo : Nicolas Fromont - @nicolasfromontphoto
Sailor and jeweler
Working on a ship requires rigor, organization and coordination. It's also a manual job. For Aurore, who is a sailor, the manual side is also very creative! She makes jewelry from marine objects and mechanical materials of the vessel. Tonight, she offers us some original souvenirs!