ASTRA: An Automatic Spading Tool for the Remote Application at Abyssal Depths

Abstract

The future approach of the European marine research programme focuses on the establishment of multi-disciplinary networks including existing systems, and the development of new technologies for efficient installation and near real time communication. Within this framework the European Community funds the networks ORION (Ocean Research by Integrated Observation Networks - GEOSTAR 3) and ESONET 2 (European Seafloor Observatory NETwork) with several European partner institutions involved in marine research. Key technologies for deep-sea research have been developed in the frame of the GEOSTAR project (GEophysical and Oceanographic STation for Abyssal Research - Deep-Sea Mission). The concept comprises: • the deep-sea benthic observatory for geophysical and oceanographic purposes with its unique Data Acquisition and Control System (DACS), • the innovative underwater communication system as near real time interface, and • the deployment and recovery vehicle MODUS (MObile Docker for Underwater Sciences) for precise operations with heavy payloads. The know-how and existing equipment establishes a good basis for extensions and further developments to be used for network projects. ASTRA — an Automated Spading Tool for Remote Applications at abyssal depths — is one of these new concepts. This tool — integrated into the GEOSTAR-Bottom Station (BS) (also called node) and deployed by MODUS — will bury an Ocean Bottom Seismometer (OBS) into the sub-sea soil. The OBS will be laterally displaced to the node and connected by an umbilical. At the end of a long-term mission the node will be recovered by MODUS and the OBS is pulled out of the ground hanging underneath the node. Both components, node and OBS, will be recovered by the surface research vessel. Equipment and procedures developed within the GEOSTAR project have been focused on providing a long-term stationing on the ocean floor to perform scientific measurements. The ASTRA concept takes a next step and aims for the interaction with its environment. Based on the proven and reliable combination of the deep sea shuttle MODUS for heavy load transportation and the payload Bottom Station as the carrier of equipment the new module ASTRA will extend the spectrum of scientific operating possibilities in the deep sea adding engineering services. An iterative process with an integrated design application of a 3D-CAD-system, FEM structural analysis and Multibody Simulation (MBS) characterizes the development phase of ASTRA. Using virtual mock-up critical aspects of handling and operation can be identified, and in consequence more easily avoided. Simulation results are validated by experimental investigations. Operations with the ASTRA prototype and the complete network-system will be performed in the Tyrrhenian Sea in late summer 2003.