Planning the science

March 28, 2009

Every day after lunch, the scientists meet to schedule science events for the next few days. These meetings optimize use of the ship’s time and help experiments stay on track. Underestimating on a two- or three-day schedule means that small errors can snowball into a buildup of late deployments. During the meetings, the principal investigators must decide how much time each deployment will take.

Ben Twining and Maria Vernet study data plots to plan their sampling schedules. Photo by Debbie Nail Meyer.

Ben Twining and Maria Vernet study data plots to plan their sampling schedules. Photo by Debbie Nail Meyer.

To estimate how much time a deployment requires, the first consideration the scientist must make is where to deploy—steaming 18.5 kilometers takes about an hour. If a science event must happen 20 kilometers away from the previous event, the principal investigator must include an hour of transit time.

Once the ship arrives at the preferred location, equipment must be put into the water. For some instruments, deployments are quick and straightforward; the CTD is located in the Baltic room, which is designed specifically for CTD deployments. On the other hand, deploying ROV IceCUBE requires consideration of many variables; positioning the ship next to the iceberg, currents, water conditions, and dive objectives change with each deployment. The actual deployment takes an appreciable amount of time as well – it must be lowered into the water carefully, then its tether is constantly reeled in and out as it moves away from the ship, ascends, and descends. When the ROV is in the chemistry configuration, floats must be attached to the tether as it is paid out. With all of these considerations, a chemistry dive that needs to pump water for three hours gets scheduled for a five-hour block.

When the chemistry, microbe, and phytoplankton groups need to collect water for their experiments, they must calculate the volume they need and the rate at which the towfish or ROV can pump water. For example, when Tim Shaw’s group needs 1,000 liters of water to calculate the amount of Radium-224 in the water, they must consider that collecting so much water will take 40 minutes of pumping from the ship’s seawater system, but 1.5 hours from a deepwater towfish.

The best-prepared plans can still fall victim to weather and sea conditions; the daily science meetings help work in changes that arise. With so many people dependent on an accurate schedule, the daily meetings help keep everyone on track.

—Amanda Kahn