It has been almost a month since we left the port of Colombo to make our way to the Wharton Basin, a place so remote that I can count on one hand the number of container ships and fishing boats I saw during our three weeks there.
Last Saturday was barbecue night on the R/V Marion Dufresne, a chance for passengers and crew to mingle, cook their own dinner, and wear flip-flops on the ship’s main work deck, which is normally a safety-shoes-only zone. But rules relax on barbecue night, when everyone stands happily around a pair of open flames, sparks flying in the night as the ship pitches and rolls.
The first thing you need to know about the R/V Marion Dufresne’s engine room is that it is not a room at all. In fact, the engine — or engines, to be more precise — occupy an entire section of the ship, encompassing numerous decks from starboard to port. These decks are noisy and hot places, packed floor to ceiling, wall to wall, with ton upon ton of heavy machinery.
Some people collect stamps, while others collect the cancellations on stamps, from “fancy cancels” to first-day issues. Within the world of cancellation collectors, there is a smaller, but no less enthusiastic, group of people who collect ship cancellations, which bear the seal of the vessel and are sometimes accompanied by the signature of its captain.
This week, the lab was buzzing with anticipation as we approached a seamount (an underwater mountain formed by volcanic activity), a small section of which had been mapped during last year’s MEGATERA cruise. The presence of the seamount was hardly a mystery, but details about its bathymetry were. We were about to get the first good look at this distinctive feature of the Wharton Basin.
When the prospect of joining the MIRAGE team was dangled before me this spring, I was briefed on the nature of the survey we’d be conducting, the importance to the region of understanding why enormous earthquakes were occurring in the middle of a seafloor plate, and the impressive resumes of the scientists who would be on board. But in every conversation, there was always this promise — it’s a French ship, so the food is going to be amazing.
The less said about yesterday’s equator ceremony the better. Unfortunately, as the Communications Officer for the MIRAGE, I am duty bound to describe the events as they transpired.
Obviously, no one on deck gets to see this momentous event since it’s happening 4.5 km below sea level, but the pipe’s collision with the seafloor can be followed on a monitor that tracks the tension of the polymer cable. As the coring unit makes its three-to-four hour descent, the tension on the cable is about 6.5 tons — it drops to zero when the pipe hits the seafloor, then spikes to about 11 tons as it’s pulled from the sticky mud. On the way back up, which takes another three-to-four hours, the tension is greater than it was on the way down, thanks to the weight of the mud now trapped inside the pipe.
In my first post about coring, I explained why we selected our two coring sites, as well as what MIRAGE researchers hope to find once the samples we retrieved are analysed. But I left out the most fascinating part — how it’s done.
Coring is difficult work, requiring days of planning, specialised equipment, and no small amount of physical prowess. Unlike bathymetry, which is primarily experienced by staring at computer monitors for hours upon end, coring happens on deck — day or night, rain or shine. This combination of engineering know-how and man doing battle with the elements makes coring fascinating to observe.