Expendable Conductivity, Temperature and Depth (XCTD) Sensors
There are occasions, especially in a harsh environment like the Arctic Ocean, when it is not feasible to deploy a CTD package. For instance, if the ship is swaying in rough seas the crew can be placed in danger from a swinging CTD package as it is being deployed or recovered. For this reason the Polar Star is outfitted with an XCTD system, which stands for expendable CTD. These are small probes, manufactered by Sippican Inc., which are attached to the ship via a thin wire. The probes are dropped over the side and the data are fed in real time back to the ship.