In 2008, Stacy Kim arrived in Antarctica to search for life in one of the most inaccessible places on the planet: under the continent's permanent ice shelves.
The marine ecologist tossed an ice auger and a small robot into a helicopter, and flew to the ice-encased Heald Island with her research team. Hers was no typical underwater robot: Kim designed the very skinny SCINI (Submersible Capable of Under Ice Navigation and Imaging) to fit through a narrow 10-inch hole made by an ice auger of the type you'd use to go ice fishing. After setting up camp, she found a crack in the 70-meter-thick ice, drilled down, and dropped SCINI in.
"Once you get under super thick ice, there's not enough light for phytoplankton and plants so you don't expect very much in terms of life," Kim said. "I expected a desert essentially."
But that's not what she saw. As SCINI maneuvered under the ice, it captured images of corals, brittle stars, sponges and tunicates—a diverse community including predators. "The first thing that pops into your mind is, what are they eating? Where is the food? What are we missing in the picture?" Kim told me. "I'm still struggling with that question."
Kim is one of many researchers exploring beneath the Antarctic ice with the help of underwater robots designed to handle its uniquely treacherous conditions. Some, like SCINI, are remote-controlled and small; others are behemoths that collect data on their own after being programmed. All of them are working to better understand life and climate on our planet—and to prepare for ocean exploration on other planets.
SCINI testing in 2009.
"Many of these vehicles are ultimately targeted for a mission to Europa or another ice-covered body with a liquid ocean," said Kim. "And then there's exploring on our planet, since we still don't know anything about what's going on under the ice shelves."
Kim and a team of engineers designed SCINI with the goal of letting her survey under the ice spontaneously. This is why SCINI is small enough to fit down a hand-drilled hole; the fuel and man-power required to melt or blast a hole through the ice takes too much money and planning.
But SCINI's size created another problem. When you drop a small robot down a small hole, "there is only one way to come back to the surface," said Kim, "so making it inexpensive and almost disposable" was a priority. SCINI is built from off-the-shelf parts so that, if something breaks, "we can just go down to the store and replace it," said Kim.
"Antarctica is the best test bed we have on this planet for going to another planet."
Instead of using fiber optic cable to tether the ROV (remotely operated underwater vehicle) and transfer data, SCINI has regular copper and Ethernet cables, which are easier to fix in the field. Operators maneuver it from the surface with an Xbox controller, another easily replaced part. Altogether the parts cost around $30,000, "which is super cheap when you compare that to the prices of other ROVs," said Kim.
The tradeoff for this scrappiness is that SCINI can't collect a lot of data. It has two cameras; a navigation system; scaling lasers that perceive the size of objects underwater; a miniCTD probe that logs temperature, salinity and depth; and an additional depth sensor.
"SCINI was designed as a first-look vehicle," said Kim. "She's not the sort of vehicle you would use to do extensive, detailed experimental work."
For that, you need a bigger vehicle like an AUV—an autonomous underwater vehicle—that can be programmed and set free to take regular measurements. This is the kind of vehicle that Ted Maksym, an ocean physicist at Woods Hole Oceanographic Institution in Massachusetts, needed to survey the thickness of Antarctica's temporary sea ice. Unlike Arctic ice, Antarctic ice appears to grow in area each year despite our warming climate. However, ice cover doesn't tell the whole story; ice thickness could also change year to year, but no one was keeping track of it.
Doing so "meant finding someone who was crazy enough to let his vehicle go under there," he said. "That's where we found Hanu."
Hanumant Singh, a robotics engineer at Woods Hole, is the mastermind behind SeaBED, an AUV designed to study rugged areas like coral reefs and midocean ridges. Weighing in at nearly 200 kilograms, SeaBED consists of two torpedoes strapped on top of one another, which gives the AUV enough stability to hover, back up, and come to a complete stop—ideal for navigating under sea ice. It also carries many scientific instruments, including mounted cameras, multiview sonar to scan and map surfaces, an acoustic Doppler current profiler to measure velocity and navigate, a depth sensor, and an acoustic modem to transmit basic location information for navigation. The real meat is in its Linux computer, which lets researchers program SeaBED's movement so that it can run autonomously.
There was only one problem: Maksym needed a robot that could look up to measure the overhanging sea ice, and SeaBED was designed to scan the seafloor below. It was an engineering challenge, but Singh was up for it. He had to "move all the heavy stuff and put it on the top, inverting the geometry of the vehicle," Singh said. In the end, he managed to balance the ice-going SeaBED so that it could survive an environment much more treacherous than the open water for which it was originally designed. On top of cold temperatures, the floating slabs of sea ice are constantly shifting and crashing into one another.
"Under the ice, to some degree you're flying blind," said Maksym. "We put the vehicle through a small hole and then the ice starts to rotate and move around, and we can lose track of where we are."
Maksym laughed nervously as he recalls the time when SeaBED got stuck under the ice and was almost crushed by an iceberg before they could rescue it. Another time, a current pulled a SeaBED vehicle off-course and the researchers had to abandon it under the ice.
Singh believes that if you don't lose a robot, you're doing it wrong.
It sounds agonizing and frustrating, but Singh believes that if you don't lose a robot, you're doing it wrong. "The first law of underwater robotics is that the number of deployments should equal the number of recoveries. And the second law states that if you always followed the first law, then you aren't taking enough risks," he said.
"We want to put these robots in harm's way to collect data that's really important to us from a socially relevant standpoint, from a climate standpoint and to humankind," he added. "If you have 10 missions and in one of those you lose it, that's okay because you've gotten all this beautiful data."
And Maksym and Singh have gotten beautiful data. They deployed SeaBED under some 500,000 square meters of Antarctic ice in 2010, and found that the ice was thicker than previously thought. Earlier measurements put the yearly sea ice at around a meter thick; Maksym's new data, published last year, showed that it was several meters thick on average—and up to 16 meters thick in some areas.
"Sea ice is a mediator of exchange of heat between the ocean and the atmosphere, and it responds to those exchanges by either getting thicker or thinner every year as it grows and melts," said Maksym. "Without knowing how thick it is, we can't understand what the interaction between the atmosphere, the ocean and the ice is." Now that they have baseline data for thickness, they can better track and interpret any changes.
Meanwhile, Britney Schmidt, a geophysicist at Georgia Tech, is asking similar questions of the permanent Antarctic ice shelves floating offshore and their role in sea level rise. These enormous masses of ice—several kilometers thick in some places—are already in the water, so "from a sea level change perspective, they've already contributed what they're going to contribute," she said. However, the shelves are like doorstops for the massive ice sheets on land, providing stability and holding them in place. If the ice shelves melt or otherwise destabilize, the land ice could follow suit.
"Under ice shelves—especially these really huge ones—we don't understand how the water circulates," said Schmidt. "As the ocean warms, we don't really understand how much warm water is getting underneath the shelves or how far back it's getting." This warmth could melt the ice shelves from below, causing fractures and further melting.
The only way to find out is to get under the ice shelves, and for that she needed a really serious robot. Meet Artemis (Autonomous Rover/airborne-radar Transects of the Environment Beneath the McMurdo Ice Shelf), which will be deployed for the first time this fall. Artemis is a hybrid ROV/AUV that can generate "a big monster suite of measurements to characterize in-depth the environment you're looking at," said Schmidt.
Artemis has several HD cameras looking forward and up, mapping sonars, and a collection of instruments called a "science tower," which log temperature, salinity, depth, pH, chlorophyll, dissolved oxygen, turbidity and protein fluorescence.
However, Schmidt's real interest isn't in Antarctica itself. She studies Earth's ice-covered ocean to prepare for exploration of ice-covered oceans far from here—like on Jupiter's moon Europa. "I'm interested in how Europa works, that's what brought me into Antarctic stuff," she said. While Artemis will do good climatological work here on Earth, it was designed (and funded by NASA) to study Europa's ocean.
This fall, Artemis will be deployed in Antarctica for testing. Additionally, the researchers will continue to test an ice-penetrating radar system, said Schmidt, to see how its measurements from a plane compare to Artemis's measurements on the ground. This radar will be ultimately orbit Europa to characterize its ice shelves from above. Also in development isValkyrie (Very Deep Autonomous Laser-Powered Kilowatt-Class Yo-Yoing Robotic Ice Explorer), a tunneling cryobot that will melt a hole through Europa's ice. The self-propelled Valkyrie uses lasers to melt its way through the ice; in a 2014 test, it burrowed 30 meters into Alaska's Matanuska glacier.
NASA's mission to Europa is slated for the mid-2020s, said Schmidt, and they'll be on the hunt for signs of life. Until then, Antarctica's ice will provide a staging and testing ground. "You want to take [your equipment] to the place where it will be the most like it is on Europa," said Kim. "Antarctica is the best test bed we have on this planet for going to another planet."
Correction 8/12/15: An earlier version of this story said that the Valkyrie robot would be deployed with Artemis to Antarctica this fall. That is not the case; Valkyrie is testing in Alaska. We regret the error.