Day 9
08 février 2022
Nautile Operation
The conditions finally allow the submarine to resume its operations. Olivier, Frank and Carl have a long day ahead of them!
Today's mission is to move the infrastructures from the bottom to their target point; to rid them of their straps and to unwind the cables necessary for the connections thanks to the Nautile's electronic arms. Today, the pilots are accompanied by Carl, a research engineer at the CNRS. Being at the origin of the technical design of the bottom devices, he knows them best!
Let's follow the deployment of the Nautile step by step...
Crédit photo :Céline Rommevaux
The Nautile never leaves alone
The submarine is launched by means of the lift-line, the line that delicately carries the submarine to the surface.
But what is the diver doing on the roof of the Nautile? Today, it's Heinrich who is assigned to this position, and he allows the first step of detachment of the Nautile to take place!
When the Nautile is in the water, the diver unhooks the lift-line. The submarine remains attached to the vessel by the cable shown in the photo at the front of the device - called the axial. It acts as the last link with the submarine and keeps it in line with the boat. The diver then activates the Nautile's locator beacon located at the front of the device - called the Gonio. This will allow the surface team to locate the submarine in the water. Then, after the intervention of two scuba divers, he retrieves the blue strap that connects the axial to the Nautile.
You have to be fast and well prepared. The actions quickly follow one another in a stability that is difficult to maintain in front of a 19-ton machine in the swell.
Crédit photo : Nicolas Fromont - @nicolasfromontphoto
The divers
In the same time, a team on the water works on water: it ensures the second stage of detachment of the Nautile. Their boat is always positioned on the right side of the Nautile and then sends two scuba divers who must remove the axial and the blue strap (previous picture). When the blue strap is removed, it's given to the diver on top of the apparatus. The coordination between them is extremely precise, they are all three subjected to the same risks.
The scuba divers make a tour of the Nautile underwater to ensure that everything is properly in place before its immersion. They are all recovered by the boat and returned to the Pourquoi Pas?
This extremely precise technical choreography allows the Nautile to dive safely!
Crédit photo : Nicolas Fromont - @nicolasfromontphoto
Return to the ship
The team returns to the ship by means of a suspended ladder, and the ship is raised last by means of the line used to send the devices to the bottom!
Crédit photo : Nicolas Fromont - @nicolasfromontphoto
Launching of the Biocam
Tonight, it's the Biocam's turn to reach the EMSO-LO site at a depth of 2400m. It's a device developed by the National Institute of Nuclear and Particle Physics which is designed to capture bioluminescence images. It's equipped with two smart cameras whose particularity is to be able to reconstruct the bioluminescent organisms observed in three dimensions. These data will complement the images made by the hypersensitive camera of BathyBot. Scientists hope to be able to make associations between the different forms of bioluminescence and groups of organisms. Understanding bioluminescence to identify species is the dream of many of them!
Zooplankton on board!
Marthe is interested in the bioluminescence of plankton that she collects with a net; and today several animal species have been through to a photo session!
The organism on the top left belongs to the gastropod family, it's a pteropod. This word of Greek origin means "with winged feet". We can indeed notice two structures similar to wings, which are actually the feet of this gastropod. When it's in movement, it can remind us of a butterfly. After all, it's the same principle of locomotion, but in a different environment.
The organism on the bottom right is a copepod. It belongs to the crustacean family, which has an external skeleton; unlike the pteropod which is a mollusk, with a flabby body.
The zooplankton is an important element in the cycle of life. It's the first link in the food chain and ensures the transfer of atmospheric carbon dioxide from the surface to the oceanic crust. Global warming is not without effect on these populations...
Let's take the example of the pteropod described above which belongs to the gastropods family, of which many species have a shell. The same is true for planktonic species. Unfortunately, the ocean is undergoing an acidification that weakens their shells and slows their growth. The acidification of water is explained by the increase of atmospheric carbon dioxide whose dissolution increases in the oceans. This phenomenon decreases the pH of the water, making it more acidic. Planktonic species with shells, which participate in the sequestration of carbon by the ocean floor, are now threatened by the dissolution of carbon dioxide in water. A sad commentary.
Crédit photo : Marthe Vienne