Researchers return to Arctic to test integrated sensor nodes

Shimmering ice extends in all instructions so far as the attention can see. Air temperatures plunge to minus 40 levels Fahrenheit and colder with wind chills. Ocean currents drag giant swaths of ice floating at sea. Polar bears, narwhals, and different iconic Arctic species roam wild.

For every week this previous spring, MIT Lincoln Laboratory researchers Ben Evans and Dave Whelihan referred to as this place — drifting some 200 nautical miles offshore from Prudhoe Bay, Alaska, on the frozen Beaufort Sea within the Arctic Circle — residence. Two ice runways for small plane supplied their solely method out and in of this distant wilderness; heated tents supplied their solely shelter from the bitter chilly.

Right here, within the northernmost area on Earth, Evans and Whelihan joined different teams conducting fieldwork within the Arctic as a part of Operation Ice Camp (OIC) 2024, an operational train run by the U.S. Navy’s Arctic Submarine Laboratory (ASL). Using on snowmobiles and helicopters, the duo deployed a small set of built-in sensor nodes that measure every part from atmospheric situations to ice properties to the construction of water deep under the floor.

In the end, they envision deploying an unattended community of those low-cost sensor nodes throughout the Arctic to extend scientific understanding of the trending loss in sea ice extent and thickness. Warming a lot quicker than the remainder of the world, the Arctic is a floor zero for local weather change, with cascading impacts throughout the planet that embrace rising sea ranges and excessive climate. Openings within the sea ice cowl, or leads, are regarding not just for local weather change but in addition for international geopolitical competitors over transit routes and pure assets. A synoptic view of the bodily processes occurring above, at, and under sea ice is vital to figuring out why the ice is diminishing. In flip, this data may help predict when and the place fractures will happen, to tell planning and decision-making.

Winter “camp”

Each two years, OIC, beforehand referred to as Ice Train (ICEX), gives a method for the worldwide group to entry the Arctic for operational readiness workouts and scientific analysis, with the main target switching forwards and backwards; this 12 months’s focus was scientific analysis. Coordination, planning, and execution of the month-long operation is led by ASL, a division of the U.S. Navy’s Undersea Warfighting Development Center chargeable for guaranteeing the submarine drive can successfully function within the Arctic Ocean.

Making this inhospitable and unforgiving setting secure for members takes appreciable effort. The essential first step is figuring out the place to arrange camp. Within the weeks earlier than the primary members arrived for OIC 2024, ASL — with help from the U.S. Nationwide Ice Middle, College of Alaska Fairbanks Geophysical Institute, and UIC Science — flew over giant sheets of floating ice (ice floes) recognized by way of satellite tv for pc imagery, landed on some they thought may be viable websites, and drilled by the ice to verify its thickness. The ice floe should not solely be giant sufficient to accommodate building of a camp and two runways but in addition function each multiyear ice and first-year ice. Multiyear ice is thick and robust however tough, making it superb for camp setup, whereas the graceful however thinner first-year ice is best fitted to constructing runways. As soon as the suitable ice floe was chosen, ASL started to haul in gear and meals, construct infrastructure like lodging and a command middle, and fly in a small group earlier than totally operationalizing the positioning. Additionally they recognized places close to the camp for 2 Navy submarines to floor by the ice.

The greater than 200 members represented U.S. and allied forces and scientists from analysis organizations and universities. Distinguished guests from authorities workplaces additionally attended OIC to see the distinctive Arctic setting and unfolding challenges firsthand.

“Our ASL hosts do unbelievable work to construct this camp from scratch and preserve us alive,” Evans says.

Evans and Whelihan, a part of the laboratory’s Advanced Undersea Systems and Technology Group, first trekked to the Arctic in March 2022 for ICEX 2022. (The laboratory basically has been taking part since 2016 in these occasions, the primary iteration of which occurred in 1946.) There, they deployed a collection of business off-the-shelf sensors for detecting acoustic (sound) and seismic (vibration) occasions created by ice fractures or collisions, and for measuring salinity, temperature, and strain within the water under the ice. Additionally they deployed a prototype fiber-based temperature sensor array developed by the laboratory and analysis companions for exactly measuring temperature throughout the complete water column at one location, and a College of New Hampshire (UNH)−provided echosounder to research the totally different layers current within the water column. On this maiden voyage, their targets have been to evaluate how these sensors fared within the harsh Arctic situations and to gather a dataset from which attribute signatures of ice-fracturing occasions may start to be recognized. These occasions can be correlated with climate and water situations to finally provide a predictive functionality.

“We noticed actual phenomenology in our information,” Whelihan says. “However, we’re not ice specialists. What we’re good at right here on the laboratory is making and deploying sensors. That is our place on the earth of local weather science: to be an information supplier. In actual fact, we hope to open supply all of our information this 12 months in order that ice scientists can entry and analyze them after which we are able to make enhanced sensors and acquire extra information.”

Interim ice

Within the two years since that expedition, they and their colleagues have been modifying their sensor designs and deployment methods. As Evans and Whelihan discovered at ICEX 2022, to be resilient within the Arctic, a sensor should not solely be saved heat and dry throughout deployment but in addition be deployed in a method to stop breaking. Furthermore, ample energy and information hyperlinks are wanted to gather and entry sensor information.

“We are able to make cold-weather electronics, no downside,” Whelihan says. “The 2 drivers are working the sensors in an energy-starved setting — the colder it’s, the more severe batteries carry out — and holding them from getting destroyed when ice floes crash collectively as leads within the ice open up.”

Their work within the interim to OIC 2024 concerned integrating the person sensors into hardened sensor nodes and training deploying these nodes in easier-to-access places. To facilitate incorporating extra sensors right into a node, Whelihan spearheaded the event of an open-source, simply extensible {hardware} and software program structure.

In March 2023, the Lincoln Laboratory staff deployed three sensor nodes for every week on Huron Bay off Lake Superior by Michigan Tech’s Great Lakes Research Center (GLRC). Engineers from GLRC helped the staff safely arrange an operations base on the ice. They demonstrated that the sensor integration labored, and the sensor nodes proved able to surviving for no less than every week in comparatively harsh situations. The researchers recorded seismic exercise on all three nodes, equivalent to some ice breaking additional up the bay.

“Proving our sensor node in an Arctic surrogate setting supplied a stepping stone for testing in the actual Arctic,” Evans says.

Evans then obtained an invite from Ignatius Rigor, the coordinator of the International Arctic Buoy Program (IABP), to affix him on an upcoming journey to Utqiaġvik (previously Barrow), Alaska, and deploy certainly one of their seismic sensor nodes on the ice there (with assist from UIC Science). The IABP maintains a community of Arctic buoys geared up with meteorological and oceanic sensors. Knowledge collected by these buoys are shared with the operational and analysis communities to assist real-time operations (e.g., forecasting sea ice situations for coastal Alaskans) and local weather analysis. Nevertheless, these buoys are usually restricted within the frequency at which they acquire information, so phenomenology on shorter time scales essential to local weather change could also be missed. Furthermore, these buoys are troublesome and costly to deploy as a result of they’re designed to outlive within the harshest environments for years at a time.  

The laboratory-developed sensor nodes may provide a reasonable, easier-to-deploy choice for amassing extra information over shorter intervals of time. In April 2023, Evans positioned a sensor node in Utqiaġvik on landfast sea ice, which is stationary ice anchored to the seabed simply off the coast. In the course of the sensor node’s week-long deployment, a giant piece of drift ice (ice not connected to the seabed or different fastened object) broke off and crashed into the landfast ice. The occasion was recorded by a radar maintained by the College of Alaska Fairbanks that screens sea ice motion in close to actual time to warn of any instability. Although this phenomenology shouldn’t be precisely the identical as that anticipated for Arctic sea ice, the researchers have been inspired to see seismic exercise recorded by their sensor node.

In December 2023, Evans and Whelihan headed to New Hampshire, the place they performed echosounder testing in UNH’s engineering check tank and on the Piscataqua River. Along with their UNH companions, they sought to find out whether or not a low-cost, hobby-grade echosounder may detect the identical phenomenology of curiosity because the high-fidelity UNH echosounder, which might be far too pricey to deploy in sensor nodes throughout the Arctic. Within the check tank and on the river, the low-cost echosounder proved able to detecting plenty of water transferring within the water column, however with significantly much less structural element than afforded by the higher-cost choice. Seeing such dynamics is essential to inferring the place water comes from and understanding the way it impacts sea ice breakup — for instance, how heat water transferring in from the Pacific Ocean is coming into contact with and melting the ice. So, the laboratory researchers and UNH companions have been constructing a medium-fidelity, medium-cost echosounder.

In January 2024, Evans and Whelihan — together with Jehan Diaz, a fellow employees member of their analysis group — returned to GLRC. With logistical assist from their GLRC hosts, they snowmobiled throughout the ice on Portage Lake, the place they practiced a number of actions to organize for OIC 2024: augering (drilling) six-inch holes within the ice, albeit in thinner ice than that within the Arctic; putting their lengthy, pipe-like sensor nodes by these holes; working cold-hardened drones to work together with the nodes; and retrieving the nodes. Additionally they practiced sensor calibration by hitting the ice with an iron bar a ways away from the nodes and correlating this distance with the ensuing measured acoustic and seismic depth.

“Our time at GLRC helped us mitigate a number of dangers and put together to deploy these advanced methods within the Arctic,” Whelihan says.

Arctic once more

To get to OIC, Evans and Whelihan first flew to Prudhoe Bay and reacclimated to the frigid temperatures. They spent the subsequent two days on the Deadhorse Aviation Middle hangar inspecting their gear for transit-induced injury, which included squashed cables and connectors that required rejiggering.

“That’s a part of the journey story,” Evans says. “Getting stuff to Prudhoe Bay shouldn’t be your normal transport; it’s ice-road trucking.”

From there, they boarded a small plane to the ice camp.

“Despite the fact that this journey marked our second time coming right here, it was nonetheless disorienting,” Evans continues. “You land in the course of nowhere on a small plane after a couple-hour flight. You get out bundled in your entire Arctic gear on this distant, pristine setting.”

After unloading and rechecking their gear for any injury, calibrating their sensors, and attending security briefings, they have been prepared to start their experiments.

An icy scenario

Contained in the challenge tent, Evans and Whelihan deployed the UNH-supplied echosounder and a collection of ground-truth sensors on an automatic winch to profile water conductivity, temperature, and depth (CTD). Echosounder information wanted to be validated with related CTD information to find out the supply of the water within the water column. Ocean properties change as a operate of depth, and these adjustments are essential to seize, partially as a result of plenty of water coming in from the Atlantic and Pacific oceans arrive at totally different depths. Although plenty of heat water have at all times existed, local weather change–associated mechanisms at the moment are bringing them into contact with the ice.  

“As ice breaks up, wind can immediately work together with the ocean as a result of it’s missing that barrier of ice cowl,” Evans explains. “Kinetic power from the wind causes mixing within the ocean; all the nice and cozy water that used to remain at depth as a substitute will get introduced up and interacts with the ice.”

Additionally they deployed 4 of their sensor nodes a number of miles outdoors of camp. To entry this deployment website, they rode on a sled pulled by way of a snowmobile pushed by Ann Hill, an ASL subject occasion chief skilled in Arctic survival and wildlife encounters. The temperature that day was -55 F. At such a dangerously chilly temperature, frostnip and frostbite are all too widespread. To keep away from removing of gloves or different protecting clothes, the researchers enabled the nodes with WiFi functionality (the nodes even have a satellite tv for pc communications hyperlink to transmit low-bandwidth information). Massive quantities of information are robotically downloaded over WiFi to an arm-wearable haptic (touch-based) system when a person walks as much as a node.

“It was so chilly that the holes we have been drilling within the ice to achieve the water column have been freezing strong,” Evans explains. “We realized it was going to be fairly an ordeal to get our sensor nodes out of the ice.”

So, after drilling a giant gap within the ice, they deployed just one central node with all of the sensor parts: a business echosounder, an underwater microphone, a seismometer, and a climate station. They deployed the opposite three nodes, every with a seismometer and climate station, atop the ice.

“One among our design concerns was flexibility,” Whelihan says. “Every node can combine as few or as many sensors as desired.”

The small sensor array was solely amassing information for a few day when Evans and Whelihan, who have been on the time on a helicopter, noticed that their preliminary subject website had turn into utterly lower off from camp by a 150-meter-wide ice lead. They shortly returned to camp to load the instruments wanted to tug the nodes, which have been now not accessible by snowmobile. Two not too long ago arrived employees members from the Ted Stevens Middle for Arctic Safety Research supplied to assist them retrieve their nodes. The helicopter landed on the ice floe close to a crack, and the pilot informed them they’d half an hour to finish their restoration mission. By the point they’d retrieved all 4 sensors, the crack had elevated from thumb to fist measurement.

“Once we obtained residence, we analyzed the collected sensor information and noticed a spike in seismic exercise equivalent to what might be the main ice-fracturing occasion that necessitated our node restoration mission,” Whelihan says.  

The researchers additionally performed experiments with their Arctic-hardened drones to guage their utility for retrieving sensor node information and to develop ideas of operations for future capabilities.

“The thought is to have some autonomous automobile land subsequent to the node, obtain information, and are available again, like an information mule, relatively than having to expend power getting information off the system, say by way of high-speed satellite tv for pc communications,” Whelihan says. “We additionally began testing whether or not the drone is succesful by itself of discovering sensors which are continuously transferring and getting shut sufficient to them. Even flying in 25-mile-per-hour winds, and at very low temperatures, the drone labored properly.”

Except for finishing up their experiments, the researchers had the chance to work together with different members. Their “roommates” have been ice scientists from Norway and Finland. They met different ice and water scientists conducting chemistry experiments on the salt content material of ice taken from totally different depths within the ice sheet (when ocean water freezes, salt tends to get pushed out of the ice). One among their collaborators — Nicholas Schmerr, an ice seismologist from the College of Maryland — positioned high-quality geophones (for measuring vibrations within the ice) alongside their nodes deployed on the camp subject website. Additionally they met with junior enlisted submariners, who quickly got here to camp to open up spots on the submarine for distinguished guests.

“A part of what we have been doing over the past three years is constructing connections throughout the Arctic group,” Evans says. “Each time I begin to get a deal with on the phenomenology that exists out right here, I study one thing new. For instance, I didn’t know that generally a layer of ice types a little bit bit deeper than the first ice sheet, and you may really see fish swimming in between the layers.”

“Sooner or later, we have been out with our subject occasion chief, who noticed fog whereas she was wanting on the horizon and stated the ice was breaking apart,” Whelihan provides. “I stated, ‘Wait, what?’ As she defined, when an ice lead types, fog comes out of the ocean. Positive sufficient, inside half-hour, we had quarter-mile visibility, whereas beforehand it was limitless.”

Again to strong floor

Earlier than leaving, Whelihan and Evans retrieved and packed up all of the remaining sensor nodes, adopting the “go away no hint” philosophy of preserving pure locations.

“Solely a restricted variety of individuals get entry to this particular setting,” Whelihan says. “We hope to develop our footprint at these occasions in future years, giving alternatives to different laboratory employees members to attend.”

Within the meantime, they may analyze the collected sensor information and refine their sensor node design. One design consideration is the best way to replenish the sensors’ battery energy. A possible path ahead is to leverage the temperature distinction between water and air, and harvest power from the water currents transferring below ice floes. Wind power might present one other viable answer. Solar energy would solely work for a part of the 12 months as a result of the Arctic Circle undergoes intervals of full darkness.

The staff can also be looking for exterior sponsorship to proceed their work engineering sensing methods that advance the scientific group’s understanding of adjustments to Arctic ice; this work is at present funded by Lincoln Laboratory’s internally administered R&D portfolio on local weather change. And, in studying extra about this altering setting and its essential significance to strategic pursuits, they’re contemplating different sensing issues that they might deal with utilizing their Arctic engineering experience.

“The Arctic is turning into a extra seen and essential area due to the way it’s altering,” Evans concludes. “Going ahead as a rustic, we should be capable of function there.”