for National Geographic News
When you're looking for a needle in a haystack, best take a magnet. And if your haystack's the Canadian Arctic, and your needle is a ship last seen by Inuit hunters in the late 1840s, it helps to have a very good magnet.
That's the thinking behind the latest hunt for the remains of the lost voyage of Sir John Franklin, whose two ships, the Erebus and the Terror, disappeared during a quest to find a northern sea route to Asia.
The Irish-Canadian Franklin Search Expedition begins today in the Canadian Arctic, about 100 miles (160 kilometers) west of the town of Gjoa Haven, Nunavut.
The members of the expedition plan to pull a magnetometer behind a snowmobile across the ice in two areas where the remains of Franklin's ships are thought to rest beneath the frigid sea.
A magnetometer is a device that, like the magnet of a compass, reacts to changes in the earth's magnetic field. The team hopes the magnetometer will identify the wreck site by detecting the iron used in the hulls and steam engines of the sunken ships.
The Erebus and the Terror set sail from Greenhithe, England, on May 19, 1845. On board were Sir John Franklin, a crew of 129 men, and three years' provisions.
Franklin's plan was to find the Northwest Passage, a northern sea route to Asia that had eluded European explorers for hundreds of years. He was never heard from again.
When Franklin failed to report back, search expeditions were launched. The search for the remains of the voyage has continued to the present day.
Over the years, artifacts, records, and bodies were recovered, offering clues as to what happened to Franklin and his men.
The evidence indicates that Franklin died during the journey and the ships became hopelessly trapped in the ice. The expedition's second-in-command, Francis Crozier, abandoned the vessels, then led 105 men on a cold, deadly march southward.
But no traces of the Erebus and the Terror have ever been found. Only small items from the ships have washed ashore, leading the Irish-Canadian team to conclude that the wrecked ships may lie relatively intact somewhere on the ocean floor.
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