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Canadian Geographic - - CONTENTS - BY VIN­CENT MY­ERS

Ex­plor­ing car­tog­ra­phy

Mas­sive “scours” caused by drift­ing ice­bergs scar the Arc­tic seabed ( im­age 3). Some ruts are more than 25 me­tres wide and kilo­me­tres long, and may be hun­dreds of years old. Other im­ages re­veal phe­nom­ena such as large ar­eas cov­ered in pock­marks ( back­ground im­age) — pos­si­bly caused by gas de­posits — rem­i­nis­cent of a lu­nar land­scape. In Au­gust 2014, a team of sci­en­tists, engi­neers and navy per­son­nel from De­fence Re­search and De­vel­op­ment Canada (the re­search arm of Canada’s Depart­ment of Na­tional De­fence) cap­tured these sonar im­ages of nearly 30 square kilo­me­tres of seabed in the cen­tral Cana­dian Arc­tic’s Vic­to­ria Strait, a re­mote and of­ten ice­cov­ered un­der­wa­ter en­vi­ron­ment that has never been seen, far less charted. The re­searchers, part of the 2014 Vic­to­ria Strait Ex­pe­di­tion search­ing for Sir John Franklin’s lost ships HMS Terror and Ere­bus, used the aptly named Arc­tic Ex­plorer, a tor­pedo-shaped au­ton­o­mous un­der­wa­ter ve­hi­cle car­ry­ing the latest in mil­i­tary R&D equip­ment — a state-of-theart syn­thetic aper­ture sonar (SAS) sys­tem. Orig­i­nally de­signed to de­tect and clas­sify un­der­wa­ter mines, it is able to sur­vey for more than 18 hours be­fore recharg­ing, and cre­ates ul­tra-high-res­o­lu­tion im­agery over very large ar­eas. DRDC pro­duced these first im­ages of a pre­vi­ously un­mapped zone near the place where Franklin’s ships were aban­doned al­most 170 years ago. Ere­bus, of course, was later found south­east of Vic­to­ria Strait, in Queen Maud Gulf, but what Arc­tic Ex­plorer cap­tured seems to con­jure up an ex­trater­res­trial world. In ad­di­tion to huge scours and other ge­o­log­i­cal for­ma­tions, the team ob­served in­ter­est­ing phys­i­cal phe­nom­ena in­volv­ing in­ter­nal waves of fresh wa­ter from melt­ing sea ice, which travel slowly down through the salt wa­ter, caus­ing sound to bend in such a way that the fresh wa­ter cre­ates ghostly rip­ples in the sand. The frigid -1.5 C wa­ter of the Arc­tic Ar­chi­pel­ago cre­ates an ideal en­vi­ron­ment for sound prop­a­ga­tion, con­tribut­ing to un­par­al­leled sonar im­age qual­ity and range. There is po­ten­tial that these im­ages and ac­com­pa­ny­ing bathy­met­ric data, which meets t he stan­dards of t he In­ter­na­tional Hy­dro­graphic Or­ga­ni­za­tion, could be used with other data to cre­ate the first de­tailed charts of the area. The 2014 Vic­to­ria Strait Ex­pe­di­tion high­lighted the need to map and ex­plore these wa­ters, part of an Arc­tic re­gion in which hu­man ac­tiv­ity is in­creas­ing. These chal­lenges are in­spir­ing Cana­dian in­dus­try, gov­ern­ment and academia to de­velop tech­nolo­gies that can op­er­ate in one of the most dif­fi­cult en­vi­ron­ments known to hu­mankind.

How an in­no­va­tive sonar tech­nol­ogy may help map parts of Canada’s pre­vi­ously un­charted Far North

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