The Expendable Bathythermograph (XBT)
The Expendable Bathythermograph (XBT) has been used by oceanographers for many years to obtain information on the temperature structure of the ocean to depths of up to 1500 meters. The XBT, shown in Figure 1, is a probe which is dropped from a ship and measures the temperature as it falls through the water. Two very small wires transmit the temperature data to the ship where it is recorded for later analysis. The probe is designed to fall at a known rate, so that the depth of the probe can be inferred from the time since it was launched. By plotting temperature as a function of depth, the scientists can get a picture of the temperature profile of the water.
On many projects it is necessary to deploy XBTs on a 24 hour schedule as the ship steams along its course. Since a trained operator is needed to operate the system, it was necessary to send two people so that operations could be conducted around the clock. To reduce the workload, AOML has designed and is now testing an automated XBT launcher that will allow this work to be conducted by only one person. Eventually, it is hoped, the ship's crew will be able to operate the system and no operators will have to accompany the system.
A photograph of the XBT Autolauncher is shown in
Figure 2. Up to six
probes can be preloaded and then deployed at predetermined launch
times or positions.