(Reuters)
Updated: 2007-08-14 11:32

WASHINGTON -- A US Coast Guard cutter is headed to the Arctic this week on a mapping mission to determine whether part of this area can be considered US territory, after recent polar forays by Russia and Canada.

Canada's Prime Minister Stephen Harper poses for a photograph with Arctic Rangers in the Arctic port of Nanisivik, Nunavut, August 10, 2007. [Reuters]

The four-week cruise of the Coast Guard Cutter Healy starts Friday and aims to map the sea floor on the northern Chukchi Cap, an underwater plateau that extends from Alaska's North Slope some 500 miles northward.

This is the third such US Arctic mapping cruise -- others were in 2003 and 2004 -- and is not a response to a Russian mission this month to place a flag at the North Pole seabed, or a newly announced Canadian plan for an Arctic port, US scientists said.

"This cruise was planned for three years and we've had the earlier cruises; this is part of a long and ongoing program, not at all a direct response," said Larry Mayer of the University of New Hampshire, who will be on the voyage.

So why are the countries with Arctic coastlines all heading northward now?

Under the U.N. Law of the Sea treaty, every coastal state that has the potential to claim some part of the Arctic's undersea mineral wealth must make a claim to the U.N. Commission on the Limits of the Continental Shelf.

The United States is not now a party to the sea treaty, but Mayer and Andy Armstrong, a scientist with the National Oceanic and Atmospheric Administration, held out hope that Washington might join.

Armstrong, who will also be aboard the US cutter, acknowledged that this cruise will "map the location of features that would have a role in the US extension of the continental shelf."

Most of the area the scientists want to map will be covered in ice, even in the northern summer. They will use an echo sounder that bounces many bits of sound in a swath across the sea floor, Mayer said by telephone.

"We don't map just a single spot beneath the vessel," Mayer said. "We can map a wide swath beneath the vessel in relatively high resolution."

The mission will look for features specified by the treaty, including the place where the slope turns into the flat plain of the deep sea bottom, Armstrong said on the same phone call.

Coastal states have rights to resources of the sea floor of their continental shelves. Under the Law of the Sea, a country gets 200 nautical miles of continental shelf automatically but may extend that if it meets certain geologic criteria, the oceanic administration said in a statement.

The Bush administration wants Senate consent to join the Law of the Sea convention, which would give the United States the same rights as other treaty parties to protect coastal and ocean resources.