It’s been a year since a squadron of underwater robots was sent out to monitor the underside of Antarctica’s Dotson Ice Shelf, and researchers report that the whole squad has survived the harsh southern winter.
Except for one unfortunate battery-powered drone, that is.
“The one that hasn’t come back, it could be any number of things,” said Jason Gobat, a senior principal oceanographer at the University of Washington’s Applied Physics Laboratory. Maybe something broke, or maybe it got stuck in the silt at the bottom of the sea.
The good news is that two other Seaglider drones are continuing to transmit data via satellite. Four free-floating EM-APEX probes have been heard from as well.
Craig Lee, another senior principal oceanographer at the UW lab, said getting useful scientific data from the robo-squadron amounts to mission success for the research project known as Ocean Robots Beneath Ice Shelves, or ORBIS.
The experiment, supported with nearly $2 million in funding from Seattle’s Paul G. Allen Philanthropies, has shown that the robots can use acoustic signals to navigate their way under the ice shelf, monitor the water that flows into and out of the ice shelf’s subsurface cavity, and keep operating for a whole year.
“The approach and the technologies we’re using work,” Lee told GeekWire.
Another oceanographer on the research team, Pierre Dutrieux of Columbia University’s Lamont-Doherty Earth Observatory, said ORBIS’ readings could well show “how much ocean heat is going to melt the ice shelf.” Those findings, in turn, could help scientists determine how much Antarctica’s melting ice will contribute to future sea level rise.
Computer-generated sets of climate scenarios show wide variation, with average sea levels rising as little as 1 foot or as much as 8 feet. That makes a world of difference to places ranging from far-flung Pacific islands to huge stretches of U.S. coastlines.
“What we really need are observations,” Dutrieux said.
Scientists can track what’s happening at the interface between Antarctic ice shelves and the surrounding waters using human-tended underwater robots, but that’s expensive and time-consuming. The point of the ORBIS project is to show that the self-propelled, self-guided Seaglider drones and the free-floating EM-APEX probes can provide a more economical way to collect data on one of our planet’s most forbidding frontiers.
“It’s a very remote environment, both in terms of what it takes to get there, and what it takes to get under the ice,” Lee said.
During the initial months of the research campaign, the robots made their way through open sea and under the ice shelf, sampling the water and mapping the cavity interior from below. The Seagliders navigated their way as far as 30 miles into the cavity, and made trips as long as 87 miles beneath the ice. Meanwhile, the four floats followed the currents in and out of open water.
When the Antarctic winter set in, that froze out most communications with the probes.
“One of the floats, we didn’t hear from for 11 months,” said James Girton, a principal oceanographer at UW’s Applied Physics Lab. That float was apparently carried through a narrow passage that connects the Dotson Ice Shelf with the neighboring Crosson Ice Shelf, and reported home just this month.
Now that the Antarctic summer is in full swing, the robots are back in business.
The two Seaglider drones that survived the winter are still collecting data, although both of them are showing signs of battery depletion, Gobat said. The U.S. research vessel Nathaniel B. Palmer is due to be in the area in a couple of weeks, and there’s a chance the Palmer’s crew could recover the drones. But even if the drones end up being left out in the cold, that’s not the end of the world.
“The data is back, and that’s the truly valuable part of the equation,” Gobat said.
In a statement emailed to GeekWire, the Paul G. Allen Family Foundation indicated that the experiment has already proved its worth.
“To have the ocean robots survive for so long, in such harsh conditions, and return with data is deeply gratifying,” the foundation said. “Our goal in supporting this project is to increase our understanding of how the Earth is changing. It is one demonstration of how data and technology are necessary in tacking the world’s toughest challenges. We look forward to learning more as the data is analyzed.”
Lee said the next steps will be to crunch the data and write up the studies for publication, and then get ready to deploy the probes in more complex undersea environments.
UW’s Applied Physics Laboratory has built a whole fleet of probes for oceanographic studies, including five Seagliders that are on duty in Alaska’s Beaufort Sea and another set of robots that will be deployed in the Bay of Bengal next month. But for researchers who focus on the crucial interaction between the world’s oceans and the polar ice sheets, the ORBIS robo-squadron has elite status.
“It opens some very interesting perspectives for investigation,” Dutrieux said. “These are situations that we could only dream about.”