JC142 cruise blog #4 – High-seas Rescue: by Chief Scientist: Bramley Murton

Our robotic submersible Autosub6000 was heading for its last survey line during mission M136, at a depth of 3400m, when we were suddenly called off by a ‘mayday’ call from a transatlantic yacht. Leaving the sub to finish a tricky mission surveying the steep flanks of Tropic Seamount was risky: the sub could get lost and as evening was drawing in, it would surface in the dark. As we were the nearest available ship, only one and a half hours away, we immediately pulled off and made full speed to rescue the yacht’s crew.

Ship’s log showing a record-breaking 17kts on route to rescue the crew from the stricken yacht ‘Noah’.

The 36ft yacht ‘Noah’ was taking in water fast and the crew of three adults and two children told us they were preparing to abandon ship in their small inflatable life raft. With some anxiety over the threat to the safety of the yacht’s crew, Jim, our captain, requested Bob the chief engineer to give the RRS James Cook full power to all four of its engines. Making a record 17 kts, we arrived within an hour and in time to find the ‘Noah’ sinking and her five members of crew in a yellow life raft.

Stricken yacht ‘Noah, just a few hours before it sank, with her life raft containing the crew of five including two children.

The Grefrath family: skipper Alexander, his wife Alexandra, their two sons aged 10 and 12, and fellow crew member Jörg Zeibig, had left Grand Canaria on the 20^th of November on route to St Lucia. Just after 2pm Wednesday, they sent an SOS message out saying their yacht was taking in water. Their pumps were overwhelmed and they were sinking. 

The officers and crew of the RRS James Cook displayed the highest levels of seamanship in rescuing the crew of the ‘Noah’, bringing them safely aboard without any getting wet or cold.

The crew of the RRS James Cook handled the situation professionally and with great seamanship. First off the life raft was Jörg, followed by Alexandra and the two kids. The last to leave was skipper Alexander. All climbed aboard the RRS James Cook safely and were given blankets and shown to the chief scientists quarters for the duration. Despite their ordeal, the kids soon settled in and within a couple of hours had found a play-station in the lounge and were playing the racing car and football games. The following day, the rescued crew were taken on tours of the science labs, the AUV and ROV. Bob put on a special tour of the engine room, which the two kids especially enjoyed.

The Grefrath family being given a tour of the ROV ‘Isis’ by Ross (left).

After going back to retrieve our AUV, we steamed to Tenerife to drop the family off in the early hours of Friday morning. To save time, we had the shortest port-call on record, with the gangway put down and hauled back up in just 30 minutes. Jim made a phone call to headquarters and we were allowed to use three engines on our way back to Tropic Seamount. This uses a lot more fuel and special permission was required. As a result, the rescue and detour only cost us 60 hours; a small price to pay for a happy-ending to an otherwise harrowing ordeal for the crew of the ‘Noah’.

The ship’s company gives a warm send-off to the crew of the ‘Noah’.

JC142 cruise blog #3 – Geological sampling by Pierre Josso (MarineE-tech post-doc)

The half-way though milestone (known as hump-day) of the cruise has just passed! We now have a much better idea of what lurks beneath our ship, typically at water depths in the range 1000-3000m. Nearly complete surveying of the summit of the seamount by the AUV has produced excellent and detailed imagery of the sunken volcano to guide our latest ROV dives. This imagery has helped us target sediment free areas for sampling. As previously indicated, the ROV can take multiple tools depending on the objectives of the dive and one has been specifically designed for this expedition: a new rock drill. With a key objective being to study variation in the composition of the crusts in relation to depth and other morphological features of the seamount, it is of great importance to be sure that the piece of rock you are collecting on the seabed actually comes from where you think it does. This may be a problem on the flanks of the volcano where slopes of 15 to 45° are likely to result in debris moving down slope from outcrops at shallower depths. The top of the seamount is relatively flat and sometimes exposures only offers scarce loose rocks for us to pick up with the manipulator arms of the ROV. This is where the drill comes in to its own.

The rock drill is assembled on the front of the ROV for its next mission, behind is crate containing core catchers for extracting the core from the drill hole, and boxes for storing samples during the dive

When the geologist in the ROV shack sees an interesting pavement of crusts (only a geologist will say that apparently!), he gives the signal for drilling. With a barrel of 30 cm, the diamond drill typically manages to produce a complete core in about one hour. Probably not the most exciting part of dives but one of the most important and delicate operations as the drill needs to go down as straight as possible for us to recover the best sample. It took a few tries to develop the best drilling strategy…indeed a few core catchers got stuck in the seabed or the core couldn’t be recovered, but the ROV team did a great job adapting to the challenging drilling conditions and our technique (this is the first attempt at seabed drilling for them). The drilling is now as good as it can probably get. It is notable that, as far as we are aware, this is the first time ever that seamount Fe-Mn crust deposits have been sampled with an ROV-mounted drill. The drilling part of these missions (which can last for up to 24 hours) provides a short break from the almost continuous seafloor observation/mapping that the scientists undertake. The drill seems to be a particular attraction to the local crabs and shrimps, curious about this bright intruder in their dark environment.

One of the many platforms found on the top of the seamount encrusted by iron and manganese, a perfect flat platform for ROV drilling.

The drill is deployed and running with a constant weight applied by the two iron blocks lifted onto the rig once the drill bit is on the seafloor. Brown dust indicates we are drilling through crust!

As the drill goes deeper, the plume changes colour as we attack the sedimentary platform under the crusts.

In this lateral view of the drill, our sampling attracts the local residents curious about this noisy intruder. 

The drill has completed a hole in the seabed, time to grab the core, still in its hole, using the core catcher shown! The laser beams are 10cm apart.

One of the many samples we have recovered during our dives (laser dots are 10 cm apart).

During the cruise we plan to acquire a dense grid of cores to study changes in crust composition at the meter, hundreds of meter and tens of kilometer scale, with control over the location of each sample. These will be complimented by grab samples of rocks. An untold competition runs between the two science shifts to see who will bring back the biggest slab, and the race is tight as samples in the 20 to 25 kg range have already been recovered! These big pieces of rocks provide the opportunity for us to study the lateral and vertical variations in these deposits at a small scale. In total, 70 kg of rocks per dive can be acquired, if we do not take the drill or other heavy equipment. It will always be a trade-off between equipment requirements e.g. taking the drill and sample capacity on this vehicle.   

Once the ROV dive is finished, we usually have a good hour to get ready for handling the samples as the ROV is recovered from the seabed. In order to quickly process and preserve the samples we have to work as an efficient team transferring them to the lab where they are photographed, cut into slices and described before being bagged and stored for further analysis back at base. 

Back on the deck, samples are cut carefully…

…. photographed and described.

One of the cores extracted from its barrel showing crust above the phosphorite substrate.

JC142 cruise blog #2 – First Dives by Sarah Howarth (PhD student)

After two days transit we arrive at Tropic Seamount. The first piece of equipment to go overboard is the CTD (conductivity-temperature-depth) rosette. This is a series of bottles that can be lowered and then opened at specific depths to allow us to sample the seawater at different depth of the water column. With a rosette of 24 bottles that can carry 20L each, this is a lot of water to process! This time the water collected is used to sample the microbiology at different depths.

The Autonomous Underwater Vehicle (AUV), Autosub6000, is the next to go in for a 12-hour high-resolution mapping mission of the summit. This is vital information for later dives and allows us to pinpoint potentially exciting areas to explore in later dives.

Early morning start for the first AUV mission of the cruise to map the summit of Tropic Seamount.

Isis, the ROV on JC142, is used for seafloor observation and sampling, armed with 3 video cameras, 2 manipulator arms and a selection of tools that can be added depending on the main aim of the dive. Today’s aim is a 22-hour dive to deploy the lander and undertake reconnaissance on the SW area on the seamount summit. During dives seafloor observations from the ROV cameras of both the biology and geology are used to map changes in environment. 

Isis returns from the first dive for reconnaissance and the trial plume generation experiment. Samples are ready for sample processing- including one large sponge on an even larger FeMn crust slab.

First FeMn crust.

The geologists constantly ask resident marine biologist Lissette Victorero what the different sponges are called. A fish with legs adds 5 minutes entertainment to a 30 minute stretch of otherwise monotonous sediment. Sample collection is one of the most exciting exercises during dives and when the ROV comes up 22 hours later it’ s like Christmas has come early. With the ROV on deck the geologists and biologists collect the samples ready for cutting, bagging and distribution during the“sampling parties”.

The scientific party is split into two teams who do 12-hour shifts, from midnight to midday and vice versa. This allows for time at sea to be optimized and for round the clock investigations. The timetable for life on board is easiest to follow by the meals: one team lives by breakfast/lunch and the other by lunch/dinner. It does lead to some confusion saying “good morning” at midnight but it’s a good sign that you’ve settled into your shift pattern. Down-time is spent relaxing in the bar, watching movies, playing table football and most importantly, sleeping. 

Last Monday, we saw the super-moon, apparently the brightest and biggest since 1948. The sea was lit up by an eerie silvery light . With clear skies, the sight was quite breathtaking and drew lots of the ship’s company out on the foc’sle deck where there are no lights to spoil the effect. 

JC142 cruise blog #1 – Setting the scene by Chief Scientist: Bramley Murton

Saturday 29^th October, cruise JC142 left Santa Cruz, Tenerife, bound for Tropic Seamount, some 300 nautical miles SW of the Canary Islands.  We spent the preceding day on a geology field trip on Mount Teide, the islands tallest volcano. Teide is the 3rd highest volcano on Earth, rising almost 8km from the deep seafloor. The evolution of Teide and Tenerife has echoes in the formation of Tropic Seamount. On Tenerife we walked into the huge caldera and looked at the more recent peak which forms the summit of Teide. We examined cinder cones, lava flows and crystals, and discussed the distinction between minerals and life; crystals reproduce their unit cell structure and grow from chemical and energy gradients; the basic building blocks of life do much the same.

The RRS James Cook preparing to sail for Tropic Seamount. Our banner says it all, “Securing critical marine minerals for a sustainable low-carbon future”. Ferromanganese crusts forming on some ancient seamounts are rich in rare metals that are essential to making ‘green’ technologies like solar panels and wind turbines.

Tropic Seamount is one of a small province of 100 million year old underwater volcanoes SW of the Canary Islands.

Tropic Seamount started life about 120 million years ago, just after the Atlantic Ocean was born. At that time, the Atlantic was only as wide as the Red Sea, and Tropic Seamount was a palm-fringed volcanic island surrounded by a coral reef. Over the millennia, Tropic Seamount slowly sank beneath the waves. As it did so, the sea eroded the peak, giving it a flat top. Earthquakes shook the volcano causing its sides to collapse. We see the result today, a star-shaped, flat-topped seamount of the type called a gyot. Although much diminished from its former grandeur, Tropic Seamount is still 3km high and covers twice the area of the Isle of Wight.

The aim of our mission here is to understand what controls the formation and precipitation of cobalt-rich crusts on seamounts like Tropic. These crusts are potentially rich resources for scarce elements that are critical to new technologies and especially those that are used in low-carbon energy production like solar panels and wind turbines. While some seamounts are rich in these crusts, extraction of the minerals is also harmful to the immediate environment and part of our work is to study the potential impact of deep-sea mining.

During our mission we will be deploying the latest technology. The ship will use its sonar systems to map the seamount at a resolution of 25m². This provides a base map and shows us where the hard and soft rock and sediment is distributed. We use this information to map the seafloor with our robotic submarine, Autosub6000. This yellow submarine is torpedo-shaped and is sent off on its own for 24 hours at a time. The images it brings back reveal the seafloor in great detail – with a resolution of 1m² for the bathymetry and 25 cm² for the acoustic sidescan sonar pictures, showing minute details of the crusts and sediment pockets. Once these images are back on board, we chose sites to dive on with our remotely operated submarine, Isis. This vehicle hangs on a cable and we control it from a room in the ship.

 

Ella launches the Autosub6000 robot submarine from the stern of the RRS James Cook. Autosub6000 is autonomous and maps the seafloor during 24-hour missions on its own. The sub can dive to 6000m below the surface and make sonar images of the seafloor in astounding resolution and clarity.

The remotely operated vehicle ‘Isis’ is launched over the side of the RS James Cook. This robotic submarine is controlled from a room onboard. We use it to drill and collect samples of the crusts from the seafloor. We also use ‘Isis’ to conduct experiments to simulate the effects of seafloor mining and the potential impact such activity might have on the surrounding environment. Isis can dive to 6500m below the surface and operate for days without a break.

Inside the ROV 'shack' – operating the ROV is a complex task and requires the pilots and scientists to work closely together.

The lander is placed on the seafloor by the ROV and waits for the first of our experiments to generate a sediment plume.

The ROV holds a hose as it blows a sediment plume in the water up-stream from the lander. This is the first time every that an experiment has been done to simulate the potential effects of disturbance from seabed mining on the surrounding environment. It is widely thought that sediment plumes can spread far and damage vulnerable animals such as sponges and corals. We aim to explore this by conducting small-scale experiments 1000m below the surface on the seabed.

One of our aims is to explore the potential effects of deep-sea mining on the surrounding environment. For this we have built a seafloor observatory, called a seabed lander, to image and measure dust plumes as they drift across the top of the seamount. The lander is deployed by ‘Isis’ which generates sediment plumes in the water. Modelling and monitoring of the currents allows us to predict how fast and how far the plumes will drift. We position the ROV up-stream from the lander, at different distances, and generate the plumes over a period of several hours. We plan to use the Autosub6000 to swim though the plumes at a distance of 1km. This information will be combined with an ecological study of the distribution of the animals most vulnerable to sediment disturbance to assess the potential impact of seafloor mining. 

While modern civilization needs rare elements found in these deep-sea mineral deposits to function and reduce our overall planetary environmental impact, we have a duty to assess the impact that extracting these minerals may have on the immediate and local environment. These data will help shape future regulations and laws around deep-sea mining.