Polar Explorer Shackleton's Lost Ship Could Be Hidden Under Antarctic Ice
The Endurance trapped in the ice of Antarctica's Weddell Sea in 1915.
Credit: Frank Hurley, 1915 (public domain)

In one of the most epic stories in the history of polar exploration, Sir Ernest Shackleton and his crew had to ditch their bid to be the first to cross Antarctica when the steam-yacht Endurance became trapped by ice in the Weddell Sea, from February until November of 1915.

Now, just over a century later, another scientific expedition will search of the wreck of the Endurance.

The loss of the Endurance forced Shackleton and his 27 crewmembers to escape across the ice to Elephant Island, near the tip of the Antarctic Peninsula. To bring back help, Shackleton and five other crewmen then sailed in a small boat to the island of South Georgia in the southern Atlantic Ocean.

The survival of the Endurance crew — which required the men to eat their dogs at one point — is one of the most epic tales in the history of exploration, said Julian Dowdeswell, director of the Scott Polar Research Institute at the University of Cambridge in the U.K. [See Images of Ernest Shackleton's Incredible Expedition]

"It's a fantastic story," Dowdeswell told Live Science. The institute's Polar Museum keeps Shackleton's diary and other artifacts of the Endurance expedition. "It is particularly fascinating for all of us, since we hold so much of the material that has survived," Dowdeswell said.

Dowdeswell will lead an international scientific expedition to the Weddell Sea on board a South African polar research ship, the Agulhas II, during the Antarctic summer in January and February of next year. 

The main scientific purpose of the expedition will be to explore the edge of the Larsen C ice shelf adjacent to the Weddell Sea, which was exposed in July 2017 by the separation of a giant icebergknown as A-68.   

The newly exposed region is of intense interest to scientists, but treacherous weather and sea-ice conditions have so far thwarted attempts to reach it. A scientific expedition aboard a British polar research ship was forced to turn back last monthbecause of heavy sea ice.

The scientists on board the Agulhas II hope that by studying the cavity under the Larsen C ice shelf with autonomous underwater vehicles (AUVs), they can determine if the recent breakup of ice shelves along the Antarctic Peninsula is a new development in geological terms, or if it is something that has happened relatively often since the last glacial maximum, between 18,000 and 20,000 years ago.

But Dowdeswell hopes the two high-tech AUVs can also search for the wreck of Shackleton's Endurance, which was recorded as sinking about 215 miles (350 kilometers) from the edge of the ice shelf, in a part of the Weddell Sea almost always covered by sea ice that's several meters thick. [Incredible Technology: How to Explore Antarctica]

The power and size of the Agulhas II and the long-range AUVs will give the expedition an important edge in locating the shipwreck, even in the deep waters of the Weddell Sea and beneath a thick canopy of sea ice, Dowdeswell said.

Similar AUVs are being used in the continued search for the missing Malaysian airliner MH370, which is thought to have crashed somewhere in the Indian Ocean in 2014.

The wreck of the Endurance is now thought to lie in water about 9,800 feet (3,000 meters) deep, almost permanently covered by sea ice, but well within the rated depth of nearly 20,000 feet (6,000 m) of the AUVs on board the Agulhas II, Dowdeswell said.

"If we can get within even 100 kilometers [62 miles] of the site, we can launch the AUV, which can go under the ice," he said. "It is this technology that gives us the very best chance [of finding the shipwreck]."

Shackleton's diary of the expedition states that the Endurance finally sank in November 1915, after becoming trapped by sea ice in February of that year and remaining stuck throughout the Antarctic winter. [The 7 Harshest Environments on Earth]

The location where the ship sank was fixed by sextant readings taken by the ship's navigator, a New Zealander named Frank Worsley. "We have the documents that he wrote down with that final position," Dowdeswell said. "That's why we're relatively confident as to where the vessel actually went down."

Shackleton's diary described how he and the 27 crewmembers of the Endurance drifted on ice floes and in lifeboats across the Weddell Sea to Elephant Island, near the northern tip of the Antarctic Peninsula.

From there, Shackleton and five others sailed in a small lifeboat over 800 miles (1,280 km) to the subpolar island of South Georgia, where they arrived at a whaling station in May 1916, after 16 days at sea and two days crossing the snow-covered mountains of the island.

Shackleton then made four attempts by sea to rescue his remaining crew from their camp on Elephant Island, until he finally reached them on a Chilean steam tug at the end of August 1916. Astonishingly, every member of the Endurance crew survived the ordeal.

"What we hope to do is to be able to photograph and map [the wreck] in as much detail as possible," Dowdeswell said. "The intention is that we will utilize that to get a formal designation of the wreck site as an Antarctic monument, so it will be preserved in perpetuity."

The conditions on board a modern polar research vessel like the Agulhas II increased the awe felt by modern scientists for the achievements of early polar explorers like Shackleton and his crew, he said.

"They were going completely into the unknown," Dowdeswell said. "They didn't have weather forecasts; they didn't have satellites showing them what the cloud cover was. They were going with no information whatsoever, into absolutely terra incognita … I think all of us who go down there have huge respect for those early pioneers."

Original article on Live Science.