Friday 8th February
Throughout the day, the Isis ROV has been slowly but surely completing the survey lines for our first task here: make a map. With the new Reson multibeam sonar aboard Isis, and flying the vehicle at 25 metres above the seafloor, that map should be able to resolve features just a few centimetres in size. Such a detailed picture of the area should help us to plan and interpret the samples and data that we want to collect later. And although there is not much to see during this survey, it provides a useful introduction to the procedures of the ROV control centre for those who have not used Isis before, and a shakedown dive for the vehicle after storage in transit.
(Photo: Andrew Thaler)
While flying our survey lines, we've also been trailing a fine mesh net to sample the plankton just above the ocean floor. The net we are using is actually borrowed from the RV Callista, the University of Southampton's coastal research vessel. This is certainly the deepest the net has ever been, as it's usually used for teaching classes in the local estuary.
By 2020h local time the ROV had completed all the survey lines, and started to return to the canopy of quicksilver far above. Total survey time at the seafloor: 31 hours, which is one of the longer mapping surveys in the ROV's history. When back on deck, the ROV will need to be reconfigured for its next mission: collecting the hot fluids gushing from the vents, and surveying and sampling the deep-sea creatures that thrive around them.
To give the ROV team time to make the necessary changes to the vehicle, our next task will therefore be to deploy the CTD probe. This time it will to collect samples of water above the vents, to see how the hot fluids rising from them change over time and interact with the surrounding ocean. Right now, I can hear the gantry from which the CTD is lowered being extended out over the side of the ship.
So far, we are still on schedule according to the original expedition plan; though I do not expect that fortunate state to last, it's good to have a successful dive and the mapping data complete.