Snow on Ice: The little orange submarine #3
The ship bobbed lazily in the Straits of Magellan, ringed by the snow-capped mountains of the far southern Andes, the sun becoming quite warm, the water still as glass. You can imagine what song was stuck in my head as we stood on the 01 Deck looking out at the stern of the ship where the HUGIN Autonomous Underwater Vehicle (AUV) sat waiting to be deployed. It is an orange, not yellow, torpedo-shaped submarine, and unlike the one from the famous Beatles song, it is definitely uninhabitable. Instead, it will hopefully be used to venture on its own under the Thwaites and Pine Island ice shelves to map the cavity underneath and measure the water properties underneath that are both vital to predicting “How much, how fast” ice will be lost from Thwaites and its adjacent areas. Before that, though, its skills must be tested.
Today, February 1, was to be its first test deployment by the N. B. Palmer crew and technicians and of course everyone was nervous to see how it would go. The HUGIN, built by Kongsberg for the University of Gothenburg, was the first to be made for scientific research. All of its predecessors have gone to industry and the military. The AUV, named “Ran” after the Norse goddess of the sea, was purchased by Anna Wåhlin’s team from Sweden through the Knut and Alice Wallenberg Foundation. The private Swedish foundation makes expensive projects, like this one, possible for scientists in the small country.
With 20 instruments onboard for navigation, measuring water properties (e.g. temperature and salinity), taking water samples, and mapping, the HUGIN used by Wåhlin’s team will be able to capture a 3D picture of what is transpiring beneath the surface around the Amundsen Sea. Ran will be able to run missions for up to 24 hours, completely on its own. It will venture to depths up to 1.5 km (1 mile) at the front of the Thwaites and elsewhere within the Amundsen Sea, though is rated to go twice that depth. The navigation system, sitting in a sterile-looking silver sphere in the nose of the sub, uses a combination of sonar, dead reckoning, and inertial navigation to track its path underwater and keep it from bumping into any unforeseen obstacles ahead, above, or below. This AUV was designed for harsh, unchartered, and frequently changing environments: floating sea ice at the surface, deep-drafted icebergs, or a completely unknown cavity under the ice shelf. After it finishes its multi-year ITGC project, the HUGIN will eventually be available to other scientists, both from Sweden and other nations around the world, through a proposal process. This research purchase will achieve the greater good for many years to come.
Standing with a vantage point from above, scientists and crew gathered on deck to watch the marine technicians get the little orange submarine off the deck. A Zodiac (small boat) with two marine techs glided protectively near the stern. Using the stern A-frame and ropes to guide its harness, the AUV was lowered into the water, detached, and there she went. We had a bit of a "NASA moment," at that point. Maybe not the same kind of cheering you expect when a rocket safely leaves the launch pad, but a few claps, relief, and gleaming smiles to match the weather. We watched as the HUGIN continued to sit at the surface while it slowly filled with water for its dive. About 10 minutes later, the orange torpedo with its black snorkel-looking antenna faded beneath the surface. Graduate student Rachel Clark’s cheeky sentiment, she recalled later, spoke for many of us I think, “Well, hopefully it comes back.”
During this test, the AUV was to dive down to specific depths within the Straits of Magellan, navigate to several designated points, and then return to the ship four hours later. The ship, in the meantime, loitered nearby with a transducer in the water to listen and give basic commands if needed. Traveling back to the designated rendezvous point on the ship, we all gathered again to look for the AUV. Then it was sighted. The little orange submarine bobbed to the surface exactly as expected.
Ran checked out with all of the sensors for today. The successful test gets the HUGIN one step closer to the AUV test-of-all-tests: the almost completely unknown underside of the Thwaites ice shelf.