Pollution tracking   Part of an oil slick of several kilometers follows the stricken Bahamas-flagged Prestige oil tanker, second top right, that is loaded with 77,000 metric tons, 85,000 US tons, of fuel oil, as it is towed away from the northwestern coast of Spain near Muxia by two tugboats to avoid a environmental catastrophe Friday Nov. 15, 2002, after the ship sprang a leak in a storm Wednesday   Envisat's ASAR image acquired 17 November 2002 shows a double-headed oil spill originating from the stricken Prestige tanker, lying 100 km off the Spanish coast. Last update: 7 March 2007