This is a photo of a CTD (Conductivity-Temperature-Density) unit, which
the Polar Duke scientists used to collect water samples.
Twelve plastic bottles were mounted on this unit and "cocked" open. The unit was then lowered deep into the sea. The CTD unit stopped twelve times on its way back up to the sea surface. At each stop, someone delivered an electronic signal that caused a bottle to close. So the scientists were able to gather water samples from twelve different depths. The scientists "cast" the CTD unit every four hours, twenty-four hours a day.
One of my jobs on the Polar Dukewas to deliver the electronic signal that closed the bottles. I did it by pushing a red button marked "Fire." That was fun--I sometimes pretended that I was firing a torpedo! Usually I was too busy to pretend, however. Another one of my jobs was checking a monitor that told how far the CTD unit was from the bottom of the sea. A CTD unit is VERY expensive--I heard prices from $30,000 to $80,000--so it's VERY important not to let it get too close to the bottom!--Vicki Johns
Photo by Amy Schauer, University of Alaska