MABEL: Recovery Operation of the First Long-Term Heavy Benthic Laboratory in the Deep Sea of Antarctica

This paper deals with the recovery operation of the bottom station MABEL (Multidisciplinary Antarctic Benthic Laboratory) with a mass of 1,7 tons in air that has been deployed in December 2005 from the German research vessel Polarstern, by means of a release transponder at a water depth of 1850 m, close to the shelf ice edge near the German polar research station Neumayer. The project is run under the umbrella of the Italian Antarctic programme by the project leader INGV (Istituto Nazionale di Geofisica i Vulcanlogia) /1/. During the cruise ANT XXV-2 of the Polarstern (organized by the German AWI - Alfred-Wegner-Institut) the German partners TFH Berlin and TU Berlin have been participating with their module MODUS (Mobile Docker for Underwater Sciences) to recover the station from the deep sea. The special circumstances in the Antarctic sea — the ice coverage of the deployment area and the tight time schedule for the operation — make such an operation quite delicate. This paper describes the special technology used both for the station and the recovery module. The operation itself will be discussed, showing the data of operation using a combined tracking of GPS-data and the underwater positioning system Posidonia of the Polarstern. The special circumstance of the operation was the inadequate data of the position achieved during the deployment, so that a safe search strategy had to be found. The mission ended successfully on December 16th, 2008 with the recovery of the MABEL station. Simulations for the system behaviour will be shown.