Lightly tethered unmanned underwater vehicle for under-ice exploration

The Woods Hole Oceanographic Institution has been awarded funds by the National Science Foundation to develop a tethered robotic underwater vehicle for under-ice exploration by 2014. By employing a novel light-weight tether for data-only communications, the vehicle will provide the U.S. Polar Research Community with a capability to tele-operate, under direct real-time human supervision, a remotely-controlled inspection and survey vehicle under fixed ice at ranges up to 20 km distant from a support ship or other deployment site. Physical tethering of an underwater robot is required to provide low-latency, high bandwidth control and real-time data return. The vehicle will enable exploration and detailed exploration in under-ice environments through the use of high-definition video coupled to a suite of chemical and biological sensors. Long-range light-fiber tether technology provides the high bandwidth link necessary for real-time control under the direction of the science party which AUVs cannot meet.

1. Introduction and Present State of Art

Polar scientists presently lack access to effective capabilities in ice-margin and under-ice environments for examining the submerged features of ice shelves, icebergs, and sea ice as well as the seafloor under ice shelves. Conventionally-tethered ROV systems have been deployed under ice (Bono 1999, Nokin 2000), but are limited to horizontal ranges of a few hundred meters from their support ships or the ice-edge, and, consequently, impose severe restrictions in environments where under sea-ice and ice shelf ice is too thick to break. The inspection-class Submersible Capable of under Ice Navigation and Imaging (SCINI) is an exception (Cazenave 2011), having been designed for deployment through 8” diameter bore holes in sea ice. SCINI's operational record has demonstrated the value of an under-ice inspection capability but is unproven through the relatively deep holes that would be required to access the sub-glacial environment, and the vehicle's size limits it to a modest sensing payload. Autonomous underwater vehicles (AUVs) have operated successfully under sea-ice since the 1970s, e.g. Theseus (Ferguson 1999), and, more recently, under ice shelves, e.g. Autosub (McPhail 2009). These missions have yielded invaluable physical oceanographic measurements and maps of ice draft and seafloor bathymetry; however, close-up high-resolution inspection remains beyond the scope of present-day and long range acoustic telemetry.