Monday 21st June 2010

What is Isis?

Today we had another successful ROV day. We got a good collection of specimens up in the morning, after a very successful 12 hour collection dive during the night.

I am going to take the opportunity to talk a little about the ROV. ROV stands for Remotely Operated Vehicle and is, according to a member of the ROV team (who wishes to stay anonymous), ‘the best thing since sliced bread’. The ROV is basically a big robot designed to go into the deep sea to explore and to collect samples. Our ROV lives in the National Oceanography Centre, Southampton, and spends about half the year sailing the Atlantic from pole to pole. Isis is being looked after and cared for by a crack team of 8 technicians. Using a 12 hour shift system, she gets 24h care from a team of 3 at a time.

Isis being prepared for a dive

Isis is connected to the ship via a 10km umbilical cable which allows her to dive down to depths of 6000m.  She has her own 128multibeam and 200kHz sonar, which gives a 120° swath angle for producing very detailed swath images of the seabed. Flying Isis at about 30m from the seafloor gives a swath width of about 70m. The sonar is not only used for swath but also for obstacle avoidance and target detection, it has been particularly helpful when looking for lost landers (DOBO, amphitrap etc).

Isis being depoloyed for the test dive

Onboard the ship we have the ROV control centre, from here Isis is sent commands from the ship. The core team for every dive consists of 3 members of the ROV team sitting in the front operating Isis and communicating with the ship’s bridge, 2 scientists who sit in the back logging and recording, and finally a mission scientist who is responsible for whatever mission we have during that dive… may that be collection, observation or something else.  Everyone gets rotated in order to maximise the work output.

A logger's view inside the ROV control room

In order to see the deep sea, we rely on 10 cameras, 2 of which shoot in high definition. The feed from these cameras is sent to the ship via the umbilical cable and displayed on nice big flat screens in the ROV van. All footage is also recorded for later reference and analysis. Lasers affixed to the ROV provide a reference point for judging distance when looking at footage; it would be very difficult to judge the sizes of specimens without these.

In terms of sampling and storage devices, Isis has a biobox and push cores, a slurp gun, and most importantly two functional manipulators, also known as arms, which have being used for sample collection and lander rescue operations. She has her own hydraulic power unit that operates the swing arms, forward drawer manipulators, the slurp pump and the carousel rotation (one of the storage options). As well as the carousel it also has bio-boxes on either side, so we have plenty of space to store samples. The configuration of tools and storage can be altered depending on requirements.

Back at the surface after a night dive

Potentially, Isis could stay in the water indefinitely, provided all systems remain functional. Normally the time she stays down is limited by either storage capacity or leakage of hydraulic fluid. It takes quite some time to get her down to the seafloor, in our case it takes about 2 hours to reach a target depth of about 2500m.

Oh and on a completely different matter we made the astounding discovery today that Grant’s legs have gotten shorter, the good news is that they are still expandable when pulled hard enough.

Claudia Alt and Dave Edge

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