Sea? oor MappingEvolution of Ocean ExplorationMapping the Sea? oor with GeodesyBy Kira Coleyn an age where the surface of Mercury and Mars can alone, costing billions of dollars. Gravity models are power-be mapped in great detail, it’s dif? cult to imagine how ful tools for charting large areas of the ocean where tectonic around 85-95% of our ocean ? oor remain enigmatic. structures and deep ocean basins remain unmapped by ships While advanced sonar technology has allowed ships or hidden under thick sediment. to create highly detailed topographic maps, it would Now, the new marine gravity model announced by a team Itake 125-200 ship-years to survey the deep oceans of international scientists’ shows unprecedented resolution Global map of the variations in the pull of gravity derived from satellite radar altimetry. http://topex.ucsd.edu/grav_outreachMarch 201628 MTRMTR #2 (18-33).indd 28 2/19/2016 11:16:49 AM