JC010: Mud volcanoes and submarine canyons
All about...ROV Isis
The dimensions of Isis are 2.7 m length, 1.5m width, and 2m height. Isis weights 3000Kg! Its depth rating is 6500m, and it has a 10000m steel cable. Do you know why? It is because the Isis needs to be able to move away from the ship, and move around.
Inside this steel cable there a fibre-optic cable and a power cable that deliver electrical power at 3000 Volts and commands from the ship. A lot of the power is lost because of the resistance in the wires which it loses as heat energy. If it overheats it has to be doused with water from time to time. As you can see, the Isis is well-equipped and has cameras, lights and two mechanical arms. When the Isis is on the seabed, the technicians can move the arms using the joystick in the control room!
These arms can collect samples from the seafloor and put them onto an elevator platform. This way, the submarine can work more hours on the seabed while the platform is going up and down with the samples.
Using the ROV and swath bathymetry to investigate what the seabed looks like
The shape of the seafloor can be determined by using the ROV (Isis). It will “fly” above the seafloor at a height of 40m at a speed of 0.6 knots ( this is a speed used at sea and is approximately 2km/h ). It will use swath bathymetry.
This gives an image of the relief of the seafloor. Acoustic or sound waves are sent out and reflected back. Think of pixel images and light. It is like that with the ROV except it uses sound instead of light to build up the picture. It sends out 128 beams of sound waves at any one time. They reflect back and give 128 images of the sea bed below them. This can give a very clear image of 10cm resolution. Then it gradually moves back and forwards like mowing a lawn covering the area set by the computers on board. If there is anything which looks really interesting it can go back and re-examine them in more detail, flying lower this time.
Using the ROV and the mechanical arms
The ROV can use its amazing mechanical arms to collect samples which can be brought up for analysis. For example gas hydrates. [These are water with methane gas trapped in them. As they are at such high pressure that they are solid. On the surface of the Earth they would be gases] When they are brought to the surface they start to decompose and they can even catch fire as the methane is released. Rapid analysis is essential.
It all depends on what is down there; using the screens the scientists can decide if something looks interesting or not. If it is then the manipulator arms can pick it up and bring it back.