Seafloor Sounding in Polar and Remote Regions

Accurate and detailed knowledge of global bathymetry is a prerequisite for progress in numerous scientific disciplines related to earth systems. Among these are modeling of ocean circulation and its relation to climate; modeling of tides and tsunamis; describing tectonic plate structure and dynamics; understanding the formation, modification and ultimate destruction of Earth's crust; sediment transport, distribution, and thickness; paleoceanography; etc. Detailed understanding of seafloor shape and features is also necessary to select sites and routes for undersea communication cables. Detailed bathymetry is required to understand the energy and mineral potential of the seas. In two specific areas of the world oceans - the Arctic Ocean and the Southern Ocean - the existing database of bathymetry is too sparse to meet science needs. The Seafloor Sounding in Polar and Remote Regions (SSPARR) project intends to fill the bathymetry data gaps in both polar regions, by the development and deployment of unmanned drifting depth sounders with satellite telemetry. Each SSPARR buoy will incorporate a single-beam depth sounder, capable of reliably measuring ocean depths up to 5000 meters or more; a GPS receiver for geographic position determination; and a bi-directional satellite communication link for telemetering data to a shore site and for receiving commands from the shore site. A buoy control processor will receive and implement commands from the shore site; sample and archive GPS position data; initiate the depth sounding function and archive resultant data; monitor status of various buoys sensors; and respond to polling requests from the shore site by telemetering requested data. The buoy will be battery powered, with sufficient power to operate for several years (although in harsh polar environments, damage from sea ice may shorten the buoy lifetime.) With its GPS receiver and subsurface acoustic system, the SSPARR buoy may also be programmed to act as an aid to navigation for underwater vehicles, by transmitting position and time information to those vehicles by acoustic modem. A three year development is planned for the SSPARR depth sounder and buoy: In the first year, assessment and demonstration of technology required for the system is planned - a low power depth sounder capable of reliably and autonomously determining seafloor depths up to 5000 meters, integrated with a combined data acquisition, navigation, control, and telemetry system. Initial development of components of the shore site, including communication protocols, will also be accomplished in the first stage of SSPARR development. In this paper, we will present the conceptual design of the SSPARR depth sounder and buoy, and results of development and testing to date. An overview of the planned development activities leading to buoy production and system operational capability will also be presented.