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Robotics

Mystery Solved: How Robots Found Shackleton’s Long-Lost Shipwreck, ‘Endurance’

The stern of the Endurance with the name and emblematic polestar

Credit: Falklands Maritime Heritage Trust and National Geographic

Over a century after it sank into the depths of the most remote, most brutal, and least surveyed waters on the planet, the once unreachable wreck of the sail ship Endurance has finally been found—thanks to autonomous technology.

Two autonomous underwater vehicles (AUVs) spent weeks scanning the Antarctic seabed in search of the wreck of the famous British explorer Sir Ernest Shackleton’s legendary Endurance, which succumbed to the icy waters on November 21, 1915 after the pack ice in which she had been drifting for many months finally swallowed her up.

Astonishing black and white footage, shot by Frank Hurley, the Endurance’s expedition photographer, shows the ship buckling under the ever increasing pressure of the ice, 107 years ago.

Now, astonishing new footage, filmed by the AUVs’ high-definition cameras and released to the public on March 9, 2022, shows the remains of the 144-ft ship resting on the floor of the Weddell Sea, 3008 meters (10,000 ft) below the surface. Somewhat poetically, the first sighting of Endurance took place on the centenary of Shackleton’s funeral.

An underwater autonomous robot (UAV) prepares to embark on a mission into Antarctic waters to discovery the shipwrecked remnants of the vessel Endurance which sank in 1915
Credit: Credit Falklands Maritime Heritage Trust and Nick Birtwistle

Near-perfect preservation

Remarkably, Endurance appears to be in a state of near-perfect preservation, standing upright on a flat sea floor that has left her unobstructed by underwater erosion or landslides. The absence of wood-consuming microbes in the icy Antarctic waters means the timber has been perfectly preserved, and the clarity of the water—enabling visibility of a good 30 meters—further enhances the spectacle of the AUVs’ 4K video footage. Glistening in the AUVs’ lights is the ship’s brass nameplate above the polar star that acknowledged the ship’s original name, Polaris, the rigging, the colorful paintwork which gives the wreck an eerie sense of unfinished business, and the ship’s wheel, still intact on the aft well deck.

Indeed, Mensun Bound, the expedition’s director of exploration and a marine archaeologist, told the BBC, “Without any exaggeration this is the finest wooden shipwreck I have ever seen – by far. It is upright, well proud of the seabed, intact, and in a brilliant state of preservation.”

Having completed its work, and now on its return journey, the Endurance22 Expedition has in its possession not just footage and data from the wreck itself, but also valuable research findings relating to climate change, ice drifts, weather conditions, and sea ice thickness.

And it’s bringing back valuable experience of successfully deploying autonomous technology to achieve something no human could have otherwise done: locate and explore the wreck of the Endurance.

Sabertooth autonomous technology

It was all made possible with Sabertooths, which manufacturer SAAB describes as purpose-built hybrid AUVs. Capable of tethered and autonomous operation in depths of up to 4,000 meters (13,123 feet), Sabertooths can reach sites up to 100 miles from their launch ship, and use high-definition cameras, side-scan imaging capability, multi-beam sonars, and laser scanners, either to provide live data and video feeds, or to upload photos, video, and survey data when they return.

What the researchers could not do, however, was touch or disturb the ship in any way; under the terms of the 1959 Antarctic Treaty, Endurance is a protected historic monument.

“We’re leaving the wreck exactly as we found it,” broadcaster and historian Dan Snow, traveling with the expedition, told Discovery. “We’re not touching it, we’re not taking anything from it. The only thing we’re taking is data. We’re taking pictures with a laser scanner, which means a model of the wreck can be reproduced with centimeter accuracy, we’re taking photogrammetry, and we’re using techniques that have never been used at that depth before to bring back the most accurate picture possible of that wreck.”

Before they departed, the team used the AUVs to conduct a 3D lidar scan of the whole area, including the debris field. “With that we’ll be able to construct 3D models of the wreck which are millimeter perfect,” explained Bound in an interview with Discovery. “We’re going to get footage and stills and we’re going to have a fabulous photomosaic of the whole area. We have the best underwater photogrammetry in the world.”

The Endurance22 Expedition was led by the Falklands Maritime Heritage Trust, which has been searching for the ship for ten years. It set sail from Cape Town in February 2022 in the Agulhas II, a South African polar research and logistics vessel. Onboard was a team of 64 people, supported by a 46-strong crew.

The location of the Endurance’s demise had been recorded by Captain Frank Worsley, using a sextant and a theodolite, so the team knew exactly where to search—well, almost.

State-of-the-art navigation equipment at the time, Worsley’s coordinates gave a position approximately four miles north of where Endurance was found. This valuable knowledge nonetheless left researchers a vast area of seabed to cover, although the Sabertooth can scan 1,400 square meters of seabed for every meter it moves forward. But whether Worsley’s positioning was of pinpoint accuracy or not, it still put the wreck’s location in waters covered most of the time by ice.

After 10 days at sea, the Endurance22 Expedition reached the search area. Only the fourth ship ever known to have entered the Weddell Sea, Agulhas II encountered waters with much less ice coverage than Shackleton experienced in December 1914. Indeed, the 2022 expedition’s success can be attributed in part to reportedly the lowest sea ice coverage since satellite ice monitoring began in the 1970s.

However, with the ice closing in, and time running out, the researchers feared they might return empty handed. Surrounded by blizzards, snow, and storms, they sent the drone out one more time, monitoring footage from the vast, flat seabed lit up by the drones’ floodlights.

Imagine, then, the reaction when the cameras picked up a man-made structure. “There were cheers from the exhausted crew when the data showed her on the seabed,” wrote Snow. Right there, on their screens, was the first footage of the perfectly preserved 107-year-old wreck, completing what expedition leader Dr John Shears called “the most challenging shipwreck search ever undertaken.”

Autonomous technology puts an end to “forever”

The fateful Imperial Trans-Antarctic Expedition, Shackleton’s third Antarctic expedition, aimed to cross the Antarctic over land, from west to east, using supplies placed in advance by a support crew based on the east coast.

The feat was such that the next attempt was not until 43 years later.

The expedition was already hugely ambitious, an astonishing tale of good old-fashioned derring-do that would be unthinkable in the modern age.

But when, on October 27, 1915, Shackleton gave the order to abandon ship, he and his 27 fellow crew members embarked upon an almost unbelievable journey of survival. Stranded alone on the Antarctic ice, the crew had no way of communicating with the mainland, or other ships. They spent five months trekking to the edge of the sea ice and sailing in the Endurance’s lifeboats to the uninhabited Elephant Island.

From there, Shackleton and a team of five others rowed and sailed 800 nautical miles to the island of South Georgia, where they then had to cross uncharted mountains and glaciers to reach a whaling station in May 1916. Having raised the alarm, a rescue mission began that only succeeded on August 30, 1916 to reach the remaining stranded crew members on Elephant Island.

Shackleton’s book, South: The Story of Shackleton’s Last Expedition (1914-1917), describes the moment Endurance sank, using a first-hand, unattributed quote from one of the crew’s diaries: “She went down bows first, her stern raised in the air. She then gave one quick dive and the ice closed over her forever.”

Thankfully, Shackleton and all 27 crew members survived to tell the tale, and autonomous technology has put an end to “forever”—and given a whole new meaning to the word “endurance.”

A crane lowers an autonomous robot into the sea on the Endurance 22 expedition
Credit: Falklands Maritime Heritage Trust and Nick Birtwistle

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