Dowdeswell, J. A.; Evans, J.; Mugford, R.; Griffiths, G.; McPhail, S.; Millard, N.; Stevenson, P.; Brandon, M. A.; Banks, C.; Heywood, K. J.; Price, M. R.; Dodd, P. A.; Jenkins, A.; Nicholls, K. W.; Hayes, D.; Abrahamsen, E. P; Tyler, P.; Bett, B.; Jones, D.; Wadhams, P.; Wilkinson, J. P.; Stansfield, K. and Ackley, S.
Autonomous underwater vehicles (AUVs) and investigations of the ice-ocean interface: deploying the Autosub AUV in Antarctic and Arctic waters.
Journal of Glaciology, 54(187),
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Limitations of access have long restricted exploration and investigation of the cavities beneath ice shelves to a small number of drill holes. Studies of sea-ice underwater morphology are limited largely to scientific utilisation of submarines. Remotely-operated vehicles (ROVs), tethered to a mother ship by umbilical cable, have been deployed to investigate tidewater-glacier and ice-shelf margins, but their range is very restricted. The development of free-flying autonomous underwater vehicles (AUVs) with ranges of tens to hundreds of kilometres enables extensive missions to take place beneath sea ice and floating ice shelves. Autosub2 is a 3600 kg, 6.7 m long AUV, with a 1600 m operating depth and range of 400 km. A single direct-drive DC motor and five-bladed propeller produce speeds of 1 to 2 m s-1. Rear-mounted rudder and stern-plane control yaw, pitch and depth. Autosub has three sections. The front and rear sections are free-flooding, built around aluminium extrusion space-frames covered with glass-fibre reinforced plastic panels. The central section has seven 3 m long carbon-fibre reinforced plastic pressure vessels. Four tubes contain batteries powering the vehicle. The other three house vehicle control systems and sensors. The rear section houses sub-systems for navigation, control actuation and propulsion and scientific sensors (e.g. digital camera, upward-looking 300 kHz Acoustic Doppler Current Profiler (ADCP), 200 kHz multibeam receiver). The front section contains forward-looking collision sensor, emergency abort, the homing systems, ARGOS transmitters and flashing lights for relocation as well as science sensors (e.g. twin Conductivity Temperature Depth (CTD) instruments, multibeam transmitter, sub-bottom profiler, AquaLab water sampler). Payload restrictions mean that a subset of scientific instruments are actually in place on any given dive. The scientific instruments carried on Autosub are described and examples of observational data collected from each sensor in Arctic or Antarctic waters, often under floating ice shelves or sea ice, are given.
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