Still in transit towards the first station, we spent most of the day refining our sampling plans and setting up equipment. It is quite normal that everyone arrives on the cruise with long ‘wish lists’ of all the sampling they’d like to do… so we have to spend time making everyone’s plans compatible, considering the time available and also the predicted weather conditions (pretty stormy for the next few days L)
With the winds in our favour we reached the first station at 18.00. The first job was to deploy the CTD (Conductivity, Temperature, Depth sensors). Primarily the CTD gives us a profile of salinity, temperature and depth from the sea surface to the seafloor. But it is also possible to mount other equipment on the CTD frame. One of these ‘extra’ instruments that we mounted was the SVP. This instrument measures of the sound velocity at each depth through the water column. We need to know the sound velocity for using one of the instruments on the ROV, the side-scan sonar. The side-scan sonar uses acoustic signals to build up a detailed picture of the topography of the seafloor, which will be the first task of the ROV. Let’s hope the weather gets better so that we can deploy the ROV tomorrow!
Another of the ‘extra’ instruments mounted on the CTD frame were the acoustic releases. These acoustic releases will be used later on tonight so it is important we check that they are fully functioning. Acoustic releases are an essential piece of kit that is used on landers. They have a ‘claw’ that stays closed until an acoustic command is sent to open the claw. When they are mounted on landers they hold the ballast (the weight that holds the lander on the seafloor) in place during deployment. Then, when we want to retrieve the lander the acoustic release opens its claw, releasing the ballast and allowing the lander to float to the surface. By mounting the acoustic releases on the CTD frame we can safely test them at depth.
The mood on the ship has definitely shifted today to excitement and anxiety as time has now come to start deploying our equipment….