A fleet of autonomous robots will soon begin recording key parameters beneath Antarctic ice shelves to improve understanding of melting processes at the ice-water interface. NASA’s Jet Propulsion Laboratory has already tested a prototype in the Arctic.
How fast is the Antarctic ice shelf melting, and how quickly could this contribute to rising global sea levels? These are the two central questions that NASA’s Jet Propulsion Laboratory (JPL) aims to answer through the ‘IceNode’ project. To gather the necessary data, the project team is developing autonomous underwater robots capable of measuring in-situ melting rates at the ice-ocean interface on the underside of ice shelves.
Not an easy task: The waters beneath ice shelves, which extend many kilometers into the Southern Ocean, are among the most inaccessible places on Earth. In January of this year, the autonomous underwater vehicle ‘Ran’ was lost during a research mission as part of the International Thwaites Glacier Collaboration (ITGC). Fortunately, during a successful mission in 2022, ‘Ran’ spent 27 days under the Dotson Ice Shelf, collecting valuable data on its underside topography.
IceNode is following a different approach: a fleet of autonomous underwater robots, distributed over a wide area, will simultaneously measure melting rates over the long term. The idea is to deploy a swarm of IceNodes – each robot measuring 2.4 meters in length and 25 centimetres in diameter – into the ocean at the edge of the ice shelf from a research vessel or through a borehole in the ice. Without propulsion, they are designed to use artificial intelligence to harness ocean currents allowing them to travel deep beneath the ice. “IceNodes use advanced probabilistic AI guidance techniques and state of the art ocean current models to control their depth to exploit varying current layers such that they are swept below their targets,” the project website explains.
Measurements where ice, water and land meet
The researchers are particularly targeting the grounding zone, where floating ice shelves, ocean and land meet. They are also investigating cavities beneath the ice, which are potential hotspots for accelerated melting.
Once the robots reach their target, they will release their ballast, ascend, and attach to the underside of the ice using a three-legged “landing gear.” They are designed to remain under the ice for up to a year, continuously measuring how warm, salty ocean water rises to melt the ice and how colder, fresher meltwater sinks.
At the end of their mission, the IceNodes will detach from the ice, drift with the ocean currents toward the open sea, and transmit their collected data via satellite.
“These robots are a platform to bring science instruments to the hardest-to-reach locations on Earth,” Paul Glick, a JPL robotics engineer and IceNode’s principal investigator, said in a press release. “It’s meant to be a safe, comparatively low-cost solution to a difficult problem.”
An additional advantage of the IceNode concept is its scalability; the fleet can be expanded as needed, allowing for broader coverage. This approach will, for the first time, provide a large-scale view of the variability in ice shelf melt rates and the factors influencing them. According to the project website, even a relatively small swarm of IceNodes could yield significant scientific insights, offering an efficient way to gather valuable data on polar ice dynamics.
First tests successful
A prototype of IceNode has already demonstrated its capabilities. After initial tests in Monterey Bay, California, and frozen Lake Superior, one of the Great Lakes, the project team deployed the robot under sea ice for the first time in March this year.
In the Beaufort Sea, the IceNode prototype conducted measurements of salinity, temperature, and ocean currents down to a depth of 100 meters. However, it was still tethered to the surface by a safety line during this initial deployment.
“We’re happy with the progress. The hope is to continue developing prototypes, get them back up to the Arctic for future tests below the sea ice, and eventually see the full fleet deployed underneath Antarctic ice shelves,” says Glick. “This is valuable data that scientists need. Anything that gets us closer to accomplishing that goal is exciting.”
It is not yet known when IceNode will be deployed beneath the Antarctic ice shelf for the first time.
Julia Hager, Polar Journal AG
More about this topic:
