The Canadian Coast Guard icebreaker Louis St. Laurent is seen sailing beside the U.S. Coast Guard cutter Healy last year, in this photo submitted by a Canadian crew member. (Submitted by Kelly Hansen)

Researchers for Canada and the United States are working together again this summer to map more of the Arctic seabed, gathering scientific data toward bolstering their own sovereignty claims.

The two countries are preparing for their second joint mapping expedition to map largely unknown parts of the Canada Basin, north of the Beaufort Sea. A similar mission took place last summer.

The 41-day mission will begin next week, with the U.S. Coast Guard cutter Healy and the Canadian Coast Guard icebreaker Louis St. Laurent meeting in the Beaufort Sea before heading as far north into the Canada Basin as the ice will allow.

"We have better maps of the moon than we do of our own ocean floor," Capt. Steve Barnum of the U.S. National Oceanic and Atmospheric Administration told CBC News.

"This is an area, again, that has been very difficult to get to. It's covered with ice, and the data we have is very sparse and in many cases very old."

Researchers on the joint mission will share seismic and bathymetric data to determine how far the North American continental shelf extends.

Each nation is working to extend its own sovereignty in the Arctic in such a way as to conform with the United Nations Convention on the Law of the Sea.

Canada's program 'on track'

Both countries are trying to prove their continental shelves extend beyond their existing 200-nautical-mile economic zones. At stake are areas rich in resources, such as oil and gas, which both countries hope to claim.

"Our program is actually at the moment on track," said Jacob Verhoef, who is leading the mapping efforts for Natural Resources Canada.

"We are fairly confident that we'll have a very strong submission to the UN commission by our deadline, which is the end of 2013."

Canada signed on to the international treaty in 2003. The U.S. has not yet ratified the UN treaty, but it is moving ahead with its scientific work anyway.

Arctic experts have said the U.S. and Canada will likely have some overlapping claims on the seabed in the Canada Basin, resulting in disputes.

But for now, the two countries are focusing on collecting data, said Allison Saunders, deputy director of the continental shelf division with the federal Foreign Affairs Department.

"You have to, at the very least, lay a factual foundation before we can even begin to contemplate how we would go into resolving these overlaps that would occur beyond 200 nautical miles," Saunders said.

Scientists working on the project said it will take at least two more years of joint efforts to complete the seabed mapping work.

Yukon-Alaska border dispute continues

The joint mapping effort will not extend into areas of the Canada Basin where Russia is also making sovereign claims, nor will it go into a disputed boundary area farther south between the Yukon and Alaska.

The U.S. and Canada have disagreed over the maritime boundary line between the two regions. Canada claims it extends out 200 nautical miles following the Alaska-Yukon border, while the U.S. says it runs perpendicular to the coast.

That dispute is "well managed" for now, and the Canada Basin mapping work is a bigger priority at this time, said Caterina Ventura, acting director of the Oceans and Environmental Law Division at the Foreign Affairs Department.

"At the moment, one can say that we're focusing our efforts on co-operation with regard to the mapping of the continental shelf in the area," she said.

The U.S. has made it clear that it wants the boundary dispute in the Beaufort Sea to be resolved with Canada without international interference.