Science at Sea

It was our first at-sea science meeting that highlighted to me how many different projects were on this cruise – groups are looking at ocean physics, atmospheric chemistry, glacier melt, marine biology, sea ice, and Earth structure, amongst others.

Ship polar science
Various ship-based science. Left to right: deploying an AUV submarine into the water, setting up a mooring through sea ice, retrieving ocean monitoring equipment. (Left photo by C. Rohleder, others by me)

We are referred to as “Team Geology”, and are primarily focused on understanding climate and ice sheet history in the recent geological past. We are using various ship-based tools and techniques to achieve our goals.

Sediment coring
Gravity sediment corer within its rotating metal cradle. Coring is done during the day and night. (Left photo by Stippenhauer, right by K. Streuff)

The ocean floor is mapped by sending out and then receiving an array of pulses every second, which are reflected off of the seafloor back to the underside of the ship. This helps document water depths for future ship navigation, but also records various interesting features of the ocean floor – mounds, ridges and grooves highlight the past extent of the ice sheet, when it was much larger than today.

Another on-board instrument images the structure of the sub-surface ocean floor. Sound waves are emitted from the ship at different frequencies, which penetrate through the sea floor, before being reflected back to the ship. As the ship moves forward, various layers of sediment can be recorded in the reflectors. This tool is very useful for identifying interesting sediment packages, which may provide an archive of past climate and ice sheet change.

These two techniques require 24-hour monitoring. Unfortunately my 8pm-midnight shift means that I miss out of lots of evening goings-on, including talks and social activities. But the shift is not the worst as I am often joined by good company.

Mapping and sediment cores
Daily duties. Mapping the seafloor from the on-board geophysics room (left), and splitting and describing sediment cores (right).

Science activities are roughly scheduled 1-2 days in advance, and generally occur at any time of the day and night.

A lot of science on this cruise involves putting complex, robot-like or industrial-looking objects over the side of the ship. Our group’s main activity is sediment coring using a Gravity Corer. This is a 5-10 m long metal cylinder with a heavy (1 tonne) weight at the top to help drive the corer into the sediment, and a “catcher” at the bottom to trap the cored sediment. An inner tube containing the sediment is then removed, cut into segments and split into half-cylinders. Basic sediment descriptions are then carried out on days when no coring is scheduled, before the core sections are put into storage.

This work can be seamless and very efficient – especially with some motivational tunes blaring from the Wet Lab – but it very much depends on our energy levels and supply of snacks.

Sleep is heavily compromised when science is in full flow. Most coring has so far been carried out at night, as daylight is not essential. As my main goal is onshore rock sampling, I also have to be ready for a helicopter meeting and a day of field work from 8 am most mornings. We get sleep when we can.

The first part of the cruise has been very productive for all groups involved, but as time goes by the days get shorter and temperature gets colder. As we enter sea ice, troubles are just around the corner.


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