ABYSSAL BENTHIC LABORATORY (ABEL) - A NOVEL-APPROACH FOR LONG-TERM INVESTIGATION AT ABYSSAL DEPTHS

This study assesses the feasibility of a configuration for a benthic u nderwater system, called ABEL (Abyssal BEnthic Laboratory), capable of operating both under controlled and autonomous modes for periods of s everal months to over one year at abyssal depths up to 6000 m. A netwo rk of stations, capable of different configurations, has been identifi ed as satisfying the widest range of scientific expectations, and at t he same time to address the technological challenge to increase the fe asibility of scientific investigations, even when the need is not yet well specified. The overall system consists of a central Benthic Inves tigation Laboratory, devoted to the execution of the most complex scie ntific activities, with fixed Satellite Stations acting as nodes of a measuring network and a Mobile Station extending ABEL capabilities wit h the possibility to carry out surveys over the investigation area and interventions on the fixed stations. ABEL architecture also includes a dedicated deployment and recovery module, as well as sea-surface and land-based facilities. Such an installation constitutes the sea-floor equivalent of a meteorological or geophysical laboratory. Attention h as been paid to selecting investigation tools supporting the ABEL syst em to carry out its mission with high operativity and minimal risk and environmental impact. This demands technologies to enable presence an d operation at abyssal depths for the required period of time. Presenc e can be guaranteed by proper choice of power supply and communication systems. Operations require visual and manipulative capabilities, as well as deployment and retrieval capabilities. Advanced control system architectures must be considered, along with knowledge based approach es, to comply with the requirements for autonomous control. The result s of this investigation demonstrate the feasibility of the ABEL concep t and the pre-dimensioning of its main components.