Submersible Uncovered Secret Structures and Vanishes

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Researchers at the University of Gothenburg achieved a groundbreaking feat with an unmanned submersible named ‘Ran.’ It completed the first-ever survey of the bottom of an Antarctic glacier. Over 27 days, Ran navigated over 1,000 kilometers beneath the Dotson Ice Shelf. The submersible uncovered secret structures, tear-drop-like patterns, and complex terrain of peaks, valleys, and plateau-like structures.

This survey is crucial for understanding glacier melt and its impact on sea levels. After finding the secret structures, the submersible vanished under Antarctic waters. Let’s find out the details of its findings and its sudden disappearance.

Thwaites Glacier | Requirement of A Submersible

A glacier is an accumulation of ice and snow that originates on land and slowly flows over land.

Image source: Filip Stedt/University of Gothenburg (A visualization of the tear-shaped areas underneath the Dotson Ice Shelf. – RAN Finding)

Thwaites Glacier is part of the West Antarctic Ice Sheet and is the widest glacier on Earth. It has a maximum width of 120 km and is between 800 and 1200 meters deep at its grounding line. Nicknamed the ‘Doomsday Glacier’, it has been under the close monitoring of scientists for decades. Mainly because of its potential to elevate the sea level markedly in the future. It has been described as part of the “weak underbelly” of the West Antarctic Ice Sheet. The glacier is suspected to be vulnerable to collapse even under relatively little warming. If that is to happen, the entire ice sheet is likely to eventually follow.

So far much of the information on the glacier was gathered from satellite images taken from above. However, the scientists needed a more up-close inspection to get more precise data. This is where, Ran, an Autonomous Underwater Vehicle from the University of Gothenburg comes in.

Image source: Science | How stuff works | Risk Frontiers

About the Submersible Ran

The AUV submersible– based on Kongsberg’s ubiquitous HUGIN platform – was financed with $3 million from the Knut and Alice Wallenberg Foundation in 2015. It was one of three such vehicles available in the world at the time.

The submersible was manufactured by Kongsberg Maritime A/S, in Norway. It measures 7.5 meters in length and weighs 1,850 kilograms. RAN is capable of achieving a maximum dive depth of 3,000 meters. It can also travel up to 300 kilometers with a dive duration of 36 hours.

Armed with state-of-the-art sensors, including multibeam echo sounders, conductivity, temperature, and depth sensors, side scan, and bottom-penetrating sonars, Ran’s potential as a data collector is unparalleled. Its navigation system, supported by DVL technology, ensures accuracy even in challenging underwater environments of the Antarctic.

Image source: Popular Mechanics (RAN Submersible)

1st Mission of the Submersible

Ran carried out its first mission in 2022, exploring the cavity of the Dotson ice shelf. It was a part of the International Thwaites Glacier Collaboration (ITGC), a five-year, $50 million joint U.S. and U.K. A mission to learn more about Thwaites Glacier, its past, and what the future may hold.

Ran traveled a total of over 1.000 kilometers back and forth under the glacier. It reached 17 kilometers into the cavity over 27 days.

Image credit: Science Advances Journal (Upward-looking multibeam sonar maps of the underside of DIS.
(A and B) One-meter multibeam grids showing ice base topography in the East region (E1 and C2). Color bars show the depth of the ice base. In (B), red crosses depict locations of channel-like features, and yellow star shows the location of the hot water drilling site. Profiles of the ice shelf base illustrate (C) channels and (D) terraces, with distance and depth in meters, which are also highlighted by slope derivations of the (E to G) ice base surface. Black bars in (A) and (B) are 1 km. Maps are projected in Universal Transverse Mercator zone 13S (WGS84 Datum).

Image source: Science Advances Journal (Upward-looking multibeam sonar maps of the underside of the central part of DIS.
(A) One-meter multibeam grid from the central survey region (C1) showing full-thickness ice fractures, superposed on smaller terraces. The profile in (B) shows that the northernmost fractures are generally larger and have been widened and eroded at these flanks; themselves containing (B and C) smaller subterraces. Black bar in (A) is 1 km, and all maps projected in Universal Transverse Mercator zone 13S (WGS84 Datum).

Findings

The team of researchers who operated Ran published a paper on their findings. They confirmed the hypothesis that the Glacier melts faster where strong underwater currents erode its base. The scientists were able to measure the currents below the glacier for the first time and prove why the western part of the Dotson Ice Shelf melts so fast. They also found evidence of very high melt at vertical fractures that extend through the glacier.

The researchers also found new patterns on the glacier base that raise questions. The base is not smooth, but there is a peak and valley ice-scape with plateaus and formations resembling sand dunes. The researchers hypothesize that these may have been formed by flowing water under the influence of Earth’s rotation.

These findings opened up many threads that researchers needed to focus on in the future. “It’s a bit like seeing the back of the moon for the first time,” says lead author Anna Wåhlin.

Ran Vanishes

In January 2024, two years after the first study, the team, along with Ran, returned to the Dotson ice shelf, to catalog the new changes to the ice shelf. The submersible does not have constant contact with the researchers operating it, while it’s carrying out its work underwater. Instead, the AUV follows a pre-programmed route and uses an advanced navigation system to find its way back from underneath the ice to open water.

However, after a series of successful missions, the submersible failed to return to its rendezvous point in February. A mission was immediately launched which involved searches with acoustic equipment, drones, and helicopters. However, it was like looking for a needle in a haystack. The team suspects that the AUV either ran aground or became the target of some curious seals.

This disappearance highlights the inherent risks of conducting cutting-edge scientific exploration in remote and challenging environments. It also emphasizes the need for more protective measures to mitigate such incidents from happening in future.

The team at the University of Gothenberg hopes to replace Ran, continuing their exploration into the yet unchartered territories of the Antarctic.

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Global Warming and Glacier Melt

One of the major problems that the world faces today is the global warming. This, in turn, has many adverse consequences such as rising sea levels, and elevation of storm surges causing more events such as typhoons and hurricanes.

The Antarctic contains around 90% of the glacial cover of the earth. While they can affect the future of all life on earth, much of their secrets remain undiscovered until today. Harsh temperatures and the barren land make it inhospitable to humans. In addition, exploration of the ice is further challenged by the thick ice sheet,4,776 meters deep at its thickest. It averages 2,160 meters in thickness.

Summary

Global warming with industrialization has caused glaciers to melt, causing the rise of the sea level as well as other climatic changes affecting life on Earth. The exploration into these changes affecting the glaciers is limited by the unapproachability of the glaciers to humans. Ran was an Automatic Unmanned Vehicle that explored the glaciers and ice shelves using advanced mapping techniques. In its previous explorations, it has uncovered a lot of new data providing information on the nature of the glaciers in the Antarctic. However, it went missing during its last expedition in February 2024.