The project will support an initial, limited field-test of a new navigation capability for autonomous underwater vehicles (AUVs) operating under icebergs and ice shelves. This system will enable an AUV to navigate and position itself with-respect-to a moving ice surface, rather than with-respect-to the seafloor and/or an inertial reference frame. Expected ice motion includes both translation and rotation. To achieve this goal, maps will be generated of submerged ice surfaces, and real-time algorithms which compute the AUV's ice-relative position using sonar soundings of those surfaces will be developed and demonstrated. This capability will augment all existing AUV under-ice navigation techniques. The system will generate maps that allow a science team to select and visit under-ice sites (either with an AUV or an ROV) by providing a much broader perspective of the submerged ice surface than has ever been possible before. It will also be possible to return to specific sites for experimentation and serial observations, and includes the ability to hold station in support of imaging and sampling missions. It will also increase the safety of AUV operations in these hazardous environments. Field tests will be performed during an already funded cruise to study icebergs in the Antarctic.
