Our last day of science sampling and we are collecting water just above a site where we suspect there is low-temperature fluid flow at the seafloor 2.5km below the ship. This is the site that in 1974 was named TAG after dredging hydrothermal deposits from the eastern rift-valley wall. I worked on these precious samples much later in the 1990’s and demonstrated that hydrothermal neodymium could be traced in these ferromanganese crusts demonstrating that they formed from low-temperature vent fluids rather than from seawater. We want to see what we can see in the deep water over this site and measure the input from the seafloor.
Over the last 38 days we have put our sampling rosette into the deep water 83 times and collected nearly 30,000 litres of seawater for processing, filtering, measuring and archiving. We have pumped over 45,000 litres of seawater through our deep sea cartridges to strip out natural radioactive isotopes that we use measure time in the deep sea. We have filled the container on the aft deck with over 100 crates of samples carefully wrapped for transport around the world to our labs in the UK, the US and elsewhere. Our physics team have made over 20 million measurements of turbulence through the water column and measured the plumes wafting through the deep waters in intricate detail.
We have steamed 4200 nautical miles since we left Southampton and have over 1000 to go to get to Guadaloupe. We have drunk over 7000 cups of coffee and eaten nearly a tonne of potatoes and over a 1000 rashers of bacon. We’ve hit the gym (perhaps because of the potatoes) and collectively rowed, run and cycled thousands of kilometres. We’ve played 350 games of cribbage, nearly 500 games of table football and some challenging games of darts when the ship is rolling.
All 52 people on the ship have worked (and played) really well together on this expedition – we have made new friends and close collaborations that will last a long time. On this long passage south to Guadaloupe we are drafting the ideas for the next proposals, practicing the talks for the big conferences coming up in 2018 and of course getting our fancy-dress costumes designed and made for the ‘RPC’.