Robots Under the Ice

 New dimensions of exploration.

Robot provides unprecedented views below Antarctic ice shelf

By James Dean, Cornell Chronicle, March 2, 2023

High in a narrow, seawater-filled crevasse in the base of Antarctica’s largest ice shelf, cameras on the remotely operated Icefin underwater vehicle relayed a sudden change in scenery.

Walls of smooth, cloudy meteoric ice abruptly turned green and rougher in texture, transitioning to salty marine ice.

Nearly 1,900 feet above, near where the surface of the Ross Ice Shelf meets Kamb Ice Stream, a U.S.-New Zealand research team recognized the shift as evidence of “ice pumping” – a process never before directly observed in an ice shelf crevasse, important to its stability.

Britney Schmidt’s Icefin team, Click to open gallery view

Credit:Icefin/NASA PSTAR RISE UP/Schmidt

Members of Britney Schmidt’s Icefin team after completing their first mission exploring conditions beneath Antarctica’s Ross Ice Shelf, near where it meets Kamb Ice Stream, in December 2019.

“We were looking at ice that had just melted less than 100 feet below, flowed up into the crevasse and then refrozen,” said Justin Lawrence, visiting scholar at the Cornell Center for Astrophysics and Planetary Science in the College of Arts and Sciences (A&S). “And then it just got weirder as we went higher up.”

The Icefin robot’s unprecedented look inside a crevasse, and observations revealing more than a century of geological processes beneath the ice shelf, are detailed in “Crevasse Refreezing and Signatures of Retreat Observed at Kamb Ice Stream Grounding Zone,” published March 2 in Nature Geoscience.

The paper reports results from a 2019 field campaign to Kamb Ice Stream supported by Antarctica New Zealand and other New Zealand research agencies, led by Christina Hulbe, professor at the University of Otago, and colleagues. Through support from NASA’s Astrobiology Program, a research team led by Britney Schmidt, associate professor of astronomy and earth and atmospheric sciences in A&S and Cornell Engineering, was able to join the expedition and deploy Icefin. Schmidt’s Planetary Habitability and Technology Lab has been developing Icefin for nearly a decade, beginning at the Georgia Institute of Technology.

Combined with recently published investigations of the fast-changing Thwaites Glacier – explored the same season by a second Icefin vehicle – the research is expected to improve models of sea-level rise by providing the first high-resolution views of ice, ocean and sea floor interactions at contrasting glacier systems on the West Antarctic Ice Sheet.

Thwaites, which is exposed to warm ocean currents, is one of the continent’s most unstable glaciers. Kamb Ice Stream, where the ocean is very cold, has been stagnant since the late 1800s. Kamb currently offsets some of the ice loss from western Antarctica, but if it reactivates could increase the region’s contribution to sea-level rise by 12%.

“Antarctica is a complex system and it’s important to understand both ends of the spectrum – systems already undergoing rapid change as well as those quieter systems where future change poses a risk,” Schmidt said. “Observing Kamb and Thwaites together helps us learn more.”

NASA funded Icefin’s development and the Kamb exploration to extend ocean exploration beyond Earth. Marine ice like that found in the crevasse may be an analog for conditions on Jupiter’s icy moon Europa, the target of NASA’s Europa Clipper orbital mission slated for launch in 2024. Later lander missions might one day search directly for microbial life in the ice.