Autonomous Under-Ice Surveys for Canadian Arctic Sovereignty: Project Cornerstone

DRDC Atlantic Fact Sheet

Introduction

UNCLOS

Canada's sovereignty claims in the Arctic requires additional bathymetry measurements near the Alpha Ridge (red box).

The United Nations Convention on the Law of the Sea (UNCLOS) allows countries to identify the outer edge of the continental shelf as their exclusive economic zone (EEZ) boundary. Nations must make a submission to the Commission on the Limits of the Continental Shelf (CLCS) to definitively establish limits of the continental shelf that extend beyond 200 nautical miles. Canada is presently mapping the limits of the Atlantic and Arctic shelves for submission to the CLCS before a deadline of December 2013.

Project CORNERSTONE

Project Cornerstone will survey the seabed in two regions near the Alpha Ridge in 2010 and 2011.

Defence R&D Canada (DRDC) – Atlantic is partnering with Natural Resources Canada (NRCan) and the Department of Fisheries and Oceans (DFO) in an $8.5 M programme to determine the location of the 2500 m isobath and the foot of the North American continental slope in ice-covered waters near the Alpha Ridge. Project CORNERSTONE will develop the equipment and methodology to enable autonomous underwater vehicles (AUVs) to collect high resolution, hydrographic quality bathymetric data of the seabed. The AUV-collected bathymetry will augment previously collected spot soundings and seismic, gravity and magnetic data to substantiate Canada's CLCS submission.

Conducting the surveys in remote Arctic locations necessitates additional developments for the AUVs, designed and built by International Submarine Engineering (ISE). These include:
a. Variable AUV ballasting for under-ice manoeuvrability
b. Underwater AUV battery charging
c. AUV terminal homing for charging and recovery
d. Acoustic tracking to augment and update AUV internal navigation

Survey Missions

Due to the remoteness and the extreme environment in this Arctic region, an innovative AUV deployment scheme using multiple camps set on stable ice is planned. Two specialized battery-powered AUVs capable of 400 km mission segments will be deployed from ice camps to conduct the under-ice surveys. Short takeoff and landing (STOL) aircraft will transport the modularized AUVs and equipment to a centrally located main camp. Here a large tent over a large ice hole will be used to assemble, store, launch and recover the AUVs. For each mission segment, the AUV will follow an on-board mission plan (position and depth) while recoding data from its bathymetric sensors. At the end of a segment, the AUV will home to a transducer deployed from an ice hole at one of several small portable camps.

AUV Specifications Hull diameter 0.74 m Length 6 m Weight 1800 kg Depth Rating 5000 m Lithium ion battery bank 48.7 kWh Range 440 km Operating speed 1.5 m/s (3 kt)

An acoustic signal will command the AUV to stop and rise under the ice. A tethered Remotely Operated Vehicle (ROV) will capture the AUV charging cable and datalink. To replenish the submerged AUVs, surface generators will recharge the AUV batteries, and computers will download new missions and retrieve the collected bathymetric and navigation data.

The AUV must accurately navigate up to 400 km over a 3 day transit and surface near a pre-determined ice hole. The accuracy of the AUV's Inertial Navigation System (INS) is expected to exceed 0.1% of distance travelled, or 400 m in a 400 km transit. The ice will also drift and change an ice hole location by up to 3 km. To accommodate these errors, the AUV will have a homing and tracking transducer with a 5 to 10 km range.

AUV under ice docking and in-water battery recharging provide the highest technical risk.

Mission Schedule

AUV Payload Single & multi-beam bathymetric sonars Depth sensor Bottom/upward looking sonar Doppler velocity log Conductivity, temperature, depth (CTD) sensor INS, compass, attitude

The AUV bathymetric surveys for two Arctic regions over the Alpha Ridge are planned for 2010 and 2011. To ensure the success of these missions, test trials in 2009 at CFS Alert on Ellesmere Island will address the logistics of Arctic operations, under ice battery charging, ROV deployment, short range (less than 10 km) tracking of the AUV from an ice hole, and long range (under 50km) AUV homing. Prior to the Arctic surveys, the tests will culminate in a full 3 day AUV mission over 400 km at the Canadian Forces Maritime Experimental and Test Range (CFMETR) in Nanoose Bay, BC.

Example of AUV mission patterns over the Alpha Ridge with main (red) and portable (yellow) camps.

 

For more information

Head/Underwater Sensing
Phone: (902) 426-3100 ext. 248
E-mail:

Defence R&D Canada – Atlantic
P.O. Box 1012, Dartmouth, Nova Scotia B2Y 3Z7
Phone: (902) 426-3100 Fax: (902) 426-9654

www.atlantic.drdc-rddc.gc.ca
Fact Sheet No. MAP0809
© DRDC Atlantic 2009

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