Peering Through Polar Ice
Scientists at Lamont-Doherty Earth Observatory have designed a set of ice imaging instruments small enough to hitch a ride on planes flying over both poles on routine missions. This spring, the IcePod will begin collecting data over Greenland from the wing of a New York Air National Guard LC130 plane. IcePod will help scientists to understand how quickly the ice sheets are changing as climate warms and what this will mean for global sea levels.
144 miles separates Kangerlussuaq from Raven Camp. Not far really, just 144 miles – like traveling from the southern tip of New York City up to Albany. Flying at 270 knots we can be there in about half an hour, no time at all, and yet to the casual observer they seem worlds apart.
Kanger sits nestled in the arm of Sondrestrom Fjord, where over the years Russell Glacier has found the soft belly in the rock base, wearing the surface down flat and pushing the rock flour out to sea. Currently the tip of Russell Glacier is a full 20 kms (14 mi) up the fjord. In the summer months, as research teams move through the village, glacial meltwater fills the carved channel that borders the small town.
Meltwater Rushing Behind Kangerlussuaq, Greenland
“Summer meltwater from Russell Glacier rushes around the edge of Kangerlussuaq.”
Although modest in size by our standards, Kangerlussuaq is a transportation hub for Greenland, and has a steady year-round population of ~500 residents.
Raven Camp sits high up on the Greenland Ice Sheet on a frozen bed of ice, almost 2 kms thick (~1 mi) and millions of years in the making. At almost 7,000 feet of elevation, no seasonal change will bring a rushing river or a population to match that of Kangerlussuaq, but summer research does bring an influx of summer scientists, swelling the population beyond the posted total of 2. With a handful of tents and collapsible housing structures, Raven Camp is a “summer town.”
Today we fly to Raven Camp to complete a survey grid over the ice landing strip. A year ago the camp staff detected several cracks (crevasses) in the ice running perpendicular to the airstrip. Crevasses are to be expected around the edges of an ice sheet, where the ice is faster flowing, however, at this elevation and this far inland it is more unusual. Published data for ice movement in this area shows at the base the ice is moving about 2.5 cm a day, while at the surface ice is moving closer to 7 cm a day. It is no surprise that the ice at the base moves more slowly, a result of the increased friction at the bed causing the ice to stick and slow.
Currently measuring only 10 cms across, it certainly doesn’t seem that this could cause much trouble. But if the crevasses are deep and continue to widen, they will threaten the landing strip. A team of scientists has been collecting measurements on the ground to see if these rates are changing (2013 polarfield blog1); our job is to survey the area with our instruments. The Shallow Ice Radar and the infrared camera collect the depth of the cracks and the temperature differences as the cracks move deeper into the ice. Pulling all this data together will help us understand what is happening to the ice in this area.
Our flight grid will be flown low, at 1,000 ft. above the ice surface, one third our normal survey elevation. Two East/West lines are flown perpendicular to the landing strip at 600 meters apart. Then three tie lines are flown parallel to the runway at 100 meters apart.
Once the grid is complete, we land on the airstrip, testing the seal on the pod door and collecting some camp cargo. The landing is smooth.
Temperatures today at Raven are a warm 1°C. The snow has lost some of the crispness we had experienced when we had landed in April to install a GPS on the ice. The pod is inspected. The camp looks all but abandoned, yet a snow vehicle appears with cargo that is stashed and secured for transit. While the cargo is loaded, we snap a quick IcePod team photo.
The new eight-bladed propellers on Skier 92 do their job and the take-off is smooth for our return to Kangerlussuaq, just 144 miles, 30 minutes of transit, and yet seemingly worlds apart.
1 For more on the science being collected on the ground on ice movement: http://www.polarfield.com/blog/tag/greenland-ice-cap/
For more on IcePod: http://www.ldeo.columbia.edu
When the New York Air National Guard travels to Kangerlussuaq, they toss in a few fishing poles with the baggage for whatever few hours of free time might be available. A favored pastime for this location’s summer assignments means the local lakes are well known by the crew, so when we sat down to map out the flight plan, a request for locating lakes met with an easy nod. No problem at all. It took only seconds to register that our definition of lakes might differ from theirs.
We are interested in lakes atop the ice sheet surface, places where the ice sheet melt is puddled into lakes of various sizes. It is in locations like these lakes where water, with its darker color, absorbs more heat from the sun than the surrounding white ice surface. This process can contribute to more melt, and in some instances the water finds a weak “joint” in the ice and drains right down to the bottom. Both the extent of the ponding and this process are of interest to the science community in better understanding the ice sheet.
The guard is quick to assure us, no problem, these too can be located!
It was an “optics day,” where our focus is on the cameras in IcePod. Using both our Bobcat (visible wavelength) and our (IR) infrared cameras, we will image surface lakes and the meandering meltwater channels on the ice sheet surface, and then fly over a few of the southwest fjords to image meltwater as it plumes at the calving edge of the ice sheet. This is a day that Chris Zappa, our resident oceanographer and optics expert, has been waiting patiently for. The weather is perfect, the sky crystal clear, and the instruments are humming. We are ready to go.
The surface of the ice sheet barely resembles our April visit. Large lakes, some a mile across, are printed along the ice sheet surface, as if a skipping stone has skimmed along the surface leaving pockets of water in its wake.
These ice surface lakes are viewed more cautiously than our lakes back home, as they pose a threat of suddenly emptying through a “moulin” or drainage tube. Moulins transfer water from the surface to the bottom of the ice sheet in short order, circumventing a process that could otherwise take many thousands of years. Cutting across the surface in various patterns, meandering channels carry the melting surface water into these catchment pools. On the ice sheet these channels are the equivalent of streams from our home communities. Back home they collect runoff and drain into freshwater lakes. Here they serve the same function but are more striking, as there are no plants to screen them.
The cameras work furiously. The Bobcat, is a 29-megapixel camera. The IR samples at 100 frames per second. Both cameras collect a staggering 60 gigabytes a second. Images play across the screen showing the temperature contrasts as we move over the surface features.
We move from the ice sheet to the coastline, where rugged mountains circle Greenland’s perimeter like a crown. Fjords cut through in many areas, allowing deeply stacked ice in the interior to move off the land. Today we are flying down small “arms” of Godthaab Fjord with a focus on their leading edges, where the ice meets the Atlantic water. We are interested in how the IR camera can be used to track thermal plumes at the interface of the cold glacier meltwater and the warmer ocean water. Combining both the Bobcat and the IR cameras allows sediment plumes to be tracked moving through the fjord. Sediment should warm faster than the surrounding water, and may be transferring more heat into the system. Both will tell us about circulation, mixing and transit of the glacial meltwater systems.
Flying back down the fjord we pass over a small fishing town perched on the edge of the water. There is no apparent movement below. Perhaps they have gone fishing?
For more about the IcePod project: http://www.ldeo.columbia.edu/icepod
Even the most skilled of English language lipreaders are only able to tease apart about 30 percent of the information being shared. I learned this reading a recent article (Kolb, 20131). The author, herself deaf, went on to note that in some transmissions the information capture is higher while in others there is nothing collected. An average of 30 percent information transfer…most of us seek more information, we are curious beings. I don’t know anyone who is happy to sit comfortably saying “yes we know 30 percent, that is good enough.”
I am surrounded by question posers, information seekers, hypothesis formers – scientists are an inquisitive bunch for sure – and that is how we find ourselves back in Greenland in July seeking to learn more about the information operating underneath and deep inside this changing ice sheet, and testing just what our IcePod instruments are capable of telling us. Thirty percent is well in excess of what we currently know about ice sheets and their processes, but every line flown and piece of data collected and analyzed builds upon our current understanding.
Prior to arriving at the base for the morning, flight plans were laid well in advance. Discussions threaded through the series of meetings leading up to our return to Kangerlssuaq, piecing together the right combination of flights that would focus on testing instruments and addressing the science. Instrument range, elevation, seasonal snow conditions, old radar lines all are factored in. Once in Greenland we must weave weather and instrument issues into our planning. Weather is cloudy and reports suggest an improvement during the week, so we will shelve our camera testing for the minute and focus on instruments designed to penetrate through the clouds. Today our flight will focus on tuning our Deep Ice Radar System (DICE).
Located at the crest of the ice sheet the elevation is just over 10,500 ft. and seems just the place to test our deep ice radar. Once aloft, we head for deep ice up over Summit. The weather reports are validated – the whole area is socked in with cloud cover and the pilots switch to Instrument Flight Rules (IFR). Our survey flight at Summit is 3,000 ft. above ground level (agl), but the aircraft instruments tell us we are 13,000 ft. above sea level (asl). The ice is deep and DICE is the focus of the next few hours as we survey and resurvey in the same area with dialogue, testing, refining and learning with each pass.
A question was raised — would we want to move to a second area to look at different conditions? Checking other areas of the ice sheet is tempting, but the science team vetoes this…”We learn more by doing this now,” holding our focus on one location. So we refocused our efforts, collecting more data, making more small adjustments, and consider that with each data point we are improving our lipreading of the ice sheet.
For more about IcePod: http://www.ldeo.columbia.edu/icepod.
1Kolb, Rachel, Seeing at the speed of sound, in Standford Magazine, March/April 2013 http://alumni.stanford.edu/get/page/magazine/article/?article_id=59977
The Lamont IcePod team is a blended mix of engineers and scientists learning from each other through the design and testing of this new instrument. With a range of talents and backgrounds, the project mixes seasoned field workers with those new to field work; experienced instrument developers with those newly learning this end of engineering; and scientists with countless hours spent pouring over Greenland ice sheet data with those exploring the ice sheet for the first time. It is the opportunity for mentoring and development that comes from this mix of early career with experienced personnel that has made the IcePod Instrument Development Project a good fit for its American Recovery and Reinvestment Act funding.
So who makes up the IcePod engineering and science team? As we work through data and examine the products collected in the first part of our field season there is an opportunity to introduce members of the team and the data and instruments they operate.
Chris Bertinato trained as an aerospace engineer before joining the IcePod team. In the air he is the team’s connection to the flight decisions made by the crew. Like the members of the flight crew he dons a headset as soon as aircraft begins its warm up. The headsets are connected into the plane electronics through lengthy cabling that trails behind each set. The cabling necessitates a threading and weaving between the crew as they move about the aircraft, testing and checking equipment and switches. Watching them work one can imagine a class devoted to practicing safe maneuvering about the plane while tethered to the electronics system – something like a Maypole dance!
Chris is a main operator of the equipment rack and has responsibility for the Laser Imaging Detection And Ranging (LIDAR) system part of the optical package in the pod taking constant measurements to find the surface elevation, and the inertial navigation system (INS) used to locate or “georeference” the data. The INS is a critical navigation aid that employs several accelerometers (motion sensors) and gyroscopes (rotations sensors) to continuously calculate the position, orientation, direction and speed of the plane as it moves through space. INS were first developed for rockets, but have become essential instruments for collecting referenced data in an aircraft, since the pitch, roll and yaw of the plane (see drawing) as it moves through the air can make it difficult to correctly locate and orient the data for processing. For those of us used to flying on commercial airliners, movies and music can provide enough of a distraction that we don’t notice the regular rolling of the aircraft as it responds to buffeting by the air around it.
The cylindrical housing for the laser sits snugly in one of the pod bays with the INS sitting atop in the small grey box. The laser focuses down through a clear panel, and scans back and forth in a swath that at 3000 ft. of altitude swings approximately 3000 ft. wide collecting elevation information. The data is then fed through a processor that turns it into elevation data.
The image above shows a swath of laser data over the airbase, and can be used to help explain the instrument. The color in the image shows the reflectance of different surfaces to the laser. You will see three of the LC130 aircraft lined up across the front of the airfield, cleaned from snow and clearly outlined in the data. There are two additional aircraft positioned in the middle of the image that are still surrounded by snow and therefore remain somewhat obscured. Trees, roads and other features in the adjacent area are clearly imaged.
In Greenland Lidar will be used to assist with locating features of interest in the ice sheet. The image above of meltwater channels in Greenland will be important to track during the summer season as these channels can reactivate seasonally, becoming a blue stripe on the otherwise white landscape. These darkened blue sections will absorb more heat energy from the sun due to their altered reflectivity (albedo) encouraging additional surface melt. In an upcoming post we will discuss how the infrared camera carried in the pod will allow us to track the heat energy in the channel both in its current state, and as it begins to melt later in the season.
Lidar will also be used to detect openings in the ice sheet (crevasses). Many of the crevasses are deep yet not wide, making them difficult to detect without the assistance of instruments. Detecting crevasses is important as they pose danger for pilots attempting to land and deliver support to ground crews, can be deadly for overland traverses that are carry scientists and support staff across the ice, and can provide us with critical information on changes in the ice sheet. Lidar data collected in our IcePod flights can be used to help in all of these situations.
For more on the IcePod project: http://www.ldeo.columbia.edu/icepod
When we left Stratton Air Field almost two weeks ago, I recall smiling when a mechanical issue temporarily pulled us from the aircraft and the woman shepherding us back into the waiting area remarked, “Don’t worry, we keep doing it until we get it right!” Today we are faced with just that type of day. Testing a new system is all about running through the same set of operations “until you get it right.” For our team, this means flying the same patterns over the same locations looking for repeat targets to test and retest our instruments.
The aircrew arrives each morning ready to fly the patterns and routes we have selected. They are willing to redirect if the weather changes, or if our priorities shift, but we have stayed fairly consistent in our requests. Of course, being in Greenland, we talk about varying our plan and picking some of our science team’s favorite targets. It seems almost unfair to be here and not venture off to the fast changing Jakobshavn or Petermann glaciers. But we are a disciplined group with a specific mission…we need to do it “until we get it right.” The navigator programs the plans into his system and we are ready to fly.
We are lucky. No matter how many times we fly over the Sondrestrom Fjord, it always looks stunning: the water a deep blue, the ice pieces feathered along the edge where the floating tongue ends. Once we move over the deeper ice in the center of the glacier, we still marvel at the twisting, refrozen meltwater streams that wind across the ice face.
Over the rocky edges of the landmass it is still fascinating to see the twisting rolls of collapsing ice that pile and swirl along the brim of the flat-topped frozen lakes. The mountains themselves look like painted rocks with their smooth and shiny surfaces.
It is hard to believe one could ever tire of these flights. Each area we fly over is more stunning than the next. Today our flight is cut short. Engine trouble brings us back to the base, but we’re hoping that tomorrow we’ll be back up in the air trying one more time, “until we get it right.”
For more on this project: http://www.ldeo.columbia.edu
Holidays vary around the world with their dates and traditions, so it should have come as no surprise that we would find a holiday in our scheduled Greenland visit. Today, April 26, is “Store Bededag,” which translates as “Great Prayer Day,” brought by the Danish to Greenland when they ventured to this island from their homeland. Kangerlussuaq, and other populated areas of Greenland, are a mix of Danish and Greenlandic in people, language, food and tradition. The holiday does not stop our survey flights today, but a snow storm with low-visibility has brought us to the ground. In the end it is a good day to focus on data.
Prior to today we have completed several flights, each with a tightly designed purpose, and there is plenty of data to be gone through. With our newly designed system, each instrument must be tested individually for operational capability and range, and then assessed for the enhancement that comes from aligning the results with the data from the other instrumentation. Calibration runs are also required for some of the instruments. In the end, each flight ends with a stack of data disks which need to be reviewed in detail.
Each flight has a list of priorities designed around specific target locations and weather availability. Yesterday our target instruments were the visible and infrared cameras, the laser system and the deep ice radar system. For the two cameras we would fly down Sondrestrom Fjord building a set of matching images.
The Bobcat, our visible image camera, showed a wide swath of surface imagery, noting where fast moving ice had crumpled into bands of ridges, as well as where it had thinned, cracked, and showed evidence of refrozen melt water streams.
The Infrared Camera operates at a higher frame capture than the Bobcat, and collects temperature differences from the places where the ice has thinned or opened. The colder the surface, the blacker the infrared image; warmer surfaces show as white. The tongue of the fjord is an excellent testing area for this.
The Deep Ice Radar was being fine-tuned on this flight. Following the first Greenland test flight, the system was adjusted and the team was anxious to see the results. We headed up Russell Glacier to get to enough ice depth to receive the radar returns, but with the weather worsening and the winds kicking up, we didn’t go any further than needed.
The LIDAR (Laser Imaging Detection And Ranging) testing was our last test of the day. Designed to give us surface elevation, with repeat use it can show change in ice surface elevation over time. In order to show small change in ice elevation, a very tight accuracy is needed, on the order of 10 cms. The LIDAR calibration was designed as a gridded pattern of 4 by 4 lines flown at 170 knots of air speed. Calibration flights can be bumpy and twisty, as the plane will roll with the turns needed to create the pattern. The 20-knot headwinds cause some additional turbulence, but the full eight passes are completed before a return to the airfield.
For more on Icepod: http://www.ldeo.columbia.edu/icepod
Half of the people lining the walls of the Kangerlussuaq International Science Support (KISS) building are waiting to go north to the top of the ice sheet at Summit Camp, and the other half are waiting to go east to the top of the ice sheet at Raven Camp. The science and support teams have been ready and waiting for several days now, hoping for a break in the weather up on the ice sheet.
Ice sheets are large enough that they can create their own weather. Large mountains of ice several miles thick, they stretch into higher elevations and gather the clouds around them. The sunny but cold weather (-21 to -9 degrees C) is a tease to the group ready each morning and waiting for clearance, day after day.
For the Icepod team the waiting is just as difficult. A series of flight options have been drafted, but with the target of getting equipment and teams out to the camps, our flights are shifted for the moment to “piggybacks” with other flight missions. Piggybacks are actually an excellent opportunity for the project to show how the pod might work once the full system is tested and ready for science use. The project design is for the pod to be fully integrated into the guard’s NSF Operation Deep Freeze mission of supporting science in the polar-regions. In the future, as the LC130’s deliver cargo and personnel to the polar science camps, the pod can be switched on by the loadmaster to gather data as the aircraft transits.
Word comes mid-morning that the first flight of carpenters and materials will head to Raven Camp. There is not room for us but we are set for the second flight. The runway at Raven Camp is a groomed strip on the ice sheet, so the pod will make its first ice landing.
The first morning flight and ice landing go well for the pod, but one aircraft engine is causing some concern. The aircraft is looked over and the engine is cleared for us to take off late in the day with the second cargo delivery. We will fly out at high altitude before we stop at camp to install a temporary GPS for an Icepod GPS calibration. A forklift is used to load two large pallets of cargo onto the metal tracks that run the length of the aircraft and that assist the quick release of the supplies. The delivery at Raven Camp will be a “combat offload” with the cargo unstrapped and the plane moving forward on the ice so that the load slides out the back.The pod team is loaded and ready to head out.
Cargo Combat Offload
“Combat Offload at Camp Raven April 23, 2013 with the Icepod project. (credit Matt Patmore)”
With the cargo delivered, several of us exit the aircraft to install a GPS base station on the ice sheet so that the pod can complete its GPS calibration. A cloverleaf design will be flown with 20 to 30 degree turns closing the loops and straight lines between, while the GPS tracks the changes in direction and the movement in the air. In the pod design an array of GPS’s were mounted, one on the aircraft hatch and several on the pod itself, in order to determine the best location for “seeing” the satellites and yet be close to the instruments. The GPS is critical to all the data, used to tie back to a specific point on Earth. One station is set up back at Kangerlussuaq, and the second set up at Raven Camp will provide us a closure point so that we can tie together and adjust all the points in between.
The station is set to operate. The team returns to the aircraft from the ice sheet and the calibration is flown. A follow-up flight to Raven Camp over the next few days will retrieve the GPS station. Once completed, the team heads for home over the ice sheet for a 9 p.m. touchdown. Although the aircraft loses an engine in the return transit, the day is determined a success with the completed piggyback flights, ice ramp landings and the GPS instrument calibration.
For More on Icepod: http://www.ldeo.columbia.edu/icepod
Ravens dominate the Kangerlussuaq landscape. Perhaps it is their deep ebony color and solid frame, or perhaps it is the white stillness of winter with little else but humans moving about, but whatever the cause the ravens are a recognized presence. The towering black hill rising above the glacially carved fjord is aptly named Raven Hill and boasts a steady circling of the mythical black winged creatures calling out in their raspy voices. With ravens being much a part of the region, it seems only fitting that our first flight would be to Raven Camp in search of deep enough ice to test the Deep Ice Radar system or “D-Ice” as it is referred to.
The day starts out a bit hazy and the weather is forecast to deteriorate during the day. Most flights have been cancelled, but the Icepod team has been cleared for flight if we can manage a departure by noon and return to base by 2 p.m. Sensor and equipment adjustments keep the team busy until mid morning, and weather maps are continually being consulted for updates. Several times the planning team reconfigures the flight lines looking for the optimal plan to maximize the testing of the equipment with available time and weather considerations. Our NYANG partners are as anxious for the flight to go as the Icepod team, but if there are any weather concerns, caution must override enthusiasm. With the camp being at a higher elevation than Kangerlussuaq, the weather can vary considerably from the base.
Raven Camp lies at close to 2000 meters (~6800 ft.) elevation, where the glacial ice is approximately 1800 meters thick. “Noise” in the radar system drops after 1200-1500 meters of ice thickness, so although the weather is poor, we are hoping to get to this ice thickness to run a first real test of the D-Ice. Unlike our optical systems, the radar is not affected by poor visibility, so this is the right decision for the flight today. The plane is loaded with cold weather emergency gear, standard protocol when flying in the polar regions, and we take off down Sondrestrom fjord, making the noon flight departure time.
This series of flights is designed for instrument testing, so the science team is troubleshooting as they fly. Every instrument is tested in the short two-hour flight, and procedures are reviewed. The sound in the aircraft is deafening and earplugs are mandatory, which makes communicating challenging, but communicating is an essential part of the testing.
The plane reached the edge of the deep ice and the aircraft lowers to a survey elevation of 900 meters (3000 ft.) above the surface flying along the ice contour. The radar system is up and recording. In too short a time, the plane has reached Raven Camp, but the poor weather conditions limit our ability to see the camp below. The aircraft turns and we head back to base. In our post-flight debrief, reviewing data takes a top priority for tomorrow. With a limited number of flight hours available, every flight is precious, so we need to be sure that assessment and adjustment is made to the instruments as we go.
For more on this program see: http://www.ldeo.columbia.edu/icepod
Icepod joined the first large wave of science teams headed to Greenland via the NYANG LC130 transport system. Four LC130 aircraft were packed to bursting with pallets of equipment, supplies and science teams anxious to get to their designated research locations. Planes one and three were designated for cargo load, plane two would carry the bulk of the science personnel, including half the Icepod team, and plane four would carry Icepod with its skeletal engineering support team. 5:00 a.m. pick-ups for the science members set up the planes for staggered departures every 30 minutes starting at 8:00 a.m. With a flight time of seven hours from Schenectady NY to Kangerlussuaq Greenland, an early departure facilitates moving through customs and getting settled with the science support staff that awaits the group in Greenland.
All the aircraft were packed from end to end with either cargo or personnel. While we waited for the pallets of cargo to be loaded onto the planes the science teams’ discussion focused on how Greenland’s ice will be dissected and examined in the upcoming season. One group will look at ice surface processes using ground penetrating radar and shallow ice cores starting at the Dye 2 location, another will drop into the high elevation Summit camp to start an overland traverse examining the ice (although we learned that nighttime temperatures are running at -50 degrees C, a bit too low currently for set up). A third group will examine the firn layer (that section in the ice that is just starting to compress) over Jakonbshavn glacier, and the Icepod team will be doing their first set of instrument test flights in polar conditions looking at the ice from the bed up to the ice surface.
The science personnel were finally loaded into Plane two, which had been divided across the middle of the main cabin, to accommodate cargo aft and science teams foreward packed knee to knee in two sets of facing rows. With this heavy load the aircraft would need to stop to refuel in Goose Bay, in Labrador, Newfoundland, Canada. Goose Bay Air Base, affectionately known by many as “The Goose”, was once home to Strategic Air Command’s 95th Strategic Wing. The ice cream served to the visitors of the airfield has become part of the travel lore of the teams en route to Greenland, so by the time the wheels touched down, everyone’s thoughts had moved from polar ice to ice cream. Two baskets full of assorted Good Humor truck style ice cream were quickly dispensed and we were back up in the air and underway for the last half of the journey.
When the west coast of Greenland came into view the sun was just peaking through the clouds lying low along the tops of the coastal mountains. The shadowy ridgeline just visible through the mist was a welcome sight after seven hours of flight. Tomorrow will be a day of setting up base stations and reviewing some of the transit data, then the Icepod project will launch into its first set of Greenland test flights.
For more information on the IcePod project: http:www.ldeo.columbia.edu/icepod
Monday:The morning briefing room was filled with layers of engineers and technicians from the civilian side, matched with pilots, navigators and air support staff from the Air National Guard side. Spanning the middle were the two Systems Project Office (S.P.O.) representatives. Adding new instrumentation and equipment to any aircraft requires intense scrutiny, but on a military plane there are extra rounds of reviews and sign offs required, and it is the S.P.O. office that is responsible for overseeing this final testing and approval. Specialists at avionics (aircraft electrical systems) and aerodynamics (air interaction and flow meeting the aircraft/pod) the first part of the week was theirs as they observed, measured, questioned and weighed equipment as it was installed in the aircraft, and prepared to monitor the in-air operation of the pod for turbulence, and potential aircraft/equipment interference.
The IcePod team arrived at Stratton Air Force Base with a carefully planned schedule of equipment installation and flight-testing. One day of install followed by two days of S.P.O. testing and then five additional days available for our own flight maneuvers to test the full potential of the pod and instruments. Inside the airport hanger crates of electrical wiring, connectors, tools and supplies were piled around aircraft 21094 the LC130 labeled ‘Raven Gang’ that was selected for the test flight. The biggest item on the floor was the 700 lb. crate containing the IcePod. The plan was to finalize the installation of the 350 lb.avionics (AV) rack located inside the plane, and then move straight to installing the arm and hanging the pod. By close of business Monday the goal was that the S.P.O. ground tests to ensure all the equipment was functional could be completed.
We were set back almost before we started. Rack pieces tightly matched to the curve of the plane body needed realigning, electrical connections needed adjusting, and by 7 p.m., the arm that would hold the pod was just being connected. Adjusted plans were agreed upon with an early morning return to add the pod and complete the ground check in the a.m. with a S.P.O. flight in the p.m. Snow was predicted over the evening but for flight the weather looked promising.
Tuesday: The morning briefing covered plans for a 10 a.m. flight time, which quickly slipped to a noon decision on the possibility of an afternoon flight. With the 500-700 foot cloud base predicted to rise to 1500 feet in the afternoon, this was not unwelcome news. In the hangar, electricians and engineers worked with thick ropes of cables taming them into place, floor pieces were notched and the pod support arm and special door secured in anticipation of hanging the pod, but delays continued. Before noon, a no-flight decision for the day was reached, as work continued at a slow but steady pace to prepare for to pod. The hope was that the ground testing could be completed before the close of day and Wednesday morning would bring the first round of flight testing.
By mid-afternoon, the pod was moved into place and fastened to the arm. The first S.P.O. concern was that the pod weight be within the approved limit of 400 lbs. Airport hangars have scales for weighing pallets of equipment but for this application a high degree of accuracy was needed. The first attempt showed a more accurate set of scales was needed. Each instrument, bracket, and set of cables added weight to the pod, so locating, calibrating and lowering the pod onto an accurate set of scales provided a few tense moments until the weight was established and S.P.O. clearance for test flights was provided.
Test Flights included turbulence testing for laminar (smooth) airflow done by installing tapered lines on the pod ends with sections of string inset to demonstrate airflow – 174 sections of string were added like a lion’s mane to the pod, and extending back behind the domed door. Exterior accelerometers were added to detect and monitor vibration on the pod as the group approached a 9 p.m. close to the workday. No matter what the status of the work the plane would be released from the hangar first thing in the a.m.
Wednesday: The weather dictated the day; socked in conditions with poor visibility meant no flights. S.P.O. ground testing was completed, but flying would be pushed off another day.
Thursday: High winds and driving rain arrived during the night with the morning briefing noting that although there was a high cloud ceiling and 3000-mile visibility, 25 mph winds and turbulence would keep us grounded early in the morning, but a 10 a.m. reassessment might allow a flight later in the day. Updates during the morning cited extreme turbulence for other flights forcing additional postponements. Mid-afternoon a decision was made to take up a minimal team to complete day one of inflight S.P.O. testing. On the runway engines are fired up, first 3 then 4 then 2 and 1, ready to go, but a problem with the Auxiliary Power Unit forced the mission to abort. Cancellation, and another day gone. As we headed out for the night we were warned that the APU issue could down the plane for up to two days.
Friday The hope is for at least one flight for this week, but we worry about the news on the APU. The morning briefing notes the APU seems to be holding and the first IcePod flight is a go! The plane is prepped; we are loaded onboard. Engine 3-4-2-1 fired up and we launch down the runway only to squeal to a stop. The domed door over the pod shows as not secure. The door is re-secured. A second attempt to move down the runway ends with the same results. Support is brought on-board and the door is reinforced for take off attempt #3.
10:56 a.m. we are up! The pod is deployed, lowering flawlessly. We begin the test flight at 5000 feet but lower to 2500 feet to move under the weather. The plan includes sets of cloverleaf maneuvers banked at 30 degrees to test GPS and lasers. The turns feel steep, and the ride is bumpy but after all the waiting we are happy to be in the air. There is no electromagnetic interference between the pod equipment and the aircraft, and the exterior accelerometers show a smooth ride for the pod. Test flight #1 for S.P.O. is complete, and everyone can head home for the weekend with a sense of accomplishment. In a week that seemed filled with adages (schedules are subject to change, everything hangs on the weather, anything that can go wrong will go wrong) at least we ended with …anything good is worth waiting for!
For more on the IcePod project see: http://www.ldeo.columbia.edu/res/pi/icepod/
In 2009 it was just a dream. But creative vision, sweat equity, good partnerships and funding can bring dreams to reality, and 2013 delivered.
It was four years ago that a small team of Lamont scientists, Polar Geophysicist Robin Bell, Engineer Nick Frearson and Ocean Climate Physicist Chris Zappa, began discussions of an instrument that could be used to collect measurements on polar ice during routine field-support flights in both the Arctic and Antarctic. Named the IcePod, it would fit onto the LC130 aircraft, a massive four-engine turboprop plane that is the workhorse of the U.S. polar support services. The pod design focused on a 9 foot long cylindrical “boot” that would hold a range of instruments and gather data on ice conditions as the aircraft carried out its seasonal polar mission. The pod would be removable, fitting in the rear paratroop door, and modular allowing for a range of instruments and ultimate utility.
Funding came through special Recovery Act Funding of a National Science Foundation Major Research Instrumentation grant. NSF saw this as an opportunity for the full science community to increase data collection and understanding of polar ice conditions, yet with a significant reduction in the logistical support needed.
The polar flights for the LC130 are coordinated through NSF but flown by the New York Air National Guard, requiring close planning and coordination with both groups as the Icepod was developed. Any design would need to meet full air safety standards, cause limited drag on the aircraft and be easily mounted or removed by the air-crew as needed.
The instruments housed in and around the pod would need to be insulated from any interference with the plane and its equipment. Additionally as the pod arm is extended below the aircraft, the instruments would need to be tightly sealed for temperature control and able to pass intense turbulence testing. Calling up visions of the electromagnetic shrinking machine from “Honey I shrunk the kids,” an additional challenge was the need to fit the instruments in the small interior cubicles of the pod. Instruments and equipment were compacted and streamlined.
The starting line up of instruments:
Radar (RAdio Detection And Ranging) uses radio waves to image through the ice. In order to collect both deep and shallow ice information Icepod will carry two types of radar. Deep-Ice Radar (DICE) is a blade antenna resembling black shark fins designed to collect data thorough more than 4 km (resolution of 10 m). The DICE radar antenna will work over the deep interior of the ice sheets to measure ice thickness and bed wetness where water may be lubricating the base of the ice sheet and changing conditions. The Shallow-Ice radar (SIR) is a horn antenna for penetrating closer to the surface of the icesheet, through approximately 300 meters of snow (25 cm resolution). SIR focuses on recent processes in the snow/ice system, looking at annual rates of snow accumulation and the layer of snow (firn layer) not yet compressed into glacial ice, estimated to range in depth from 40-100 m below the surface.
Optics: Laser, is an instrument that uses light to image and collect data on surface elevation and snow texture. Two different cameras will be used to collect data on reflectivity and temperature (visible-wave and infrared cameras). As we layer together all the information collected from the instruments we can integrate our understanding of the ice conditions at the base of the ice sheet up through the internal ice layers, to the ice sheet surface, and up to the reflective return from the ice.
Next week the Lamont’s Polar Geophysics Team will fly with the New York Air National Guard, bringing the long envisioned IcePod into the air for field-testing. The team is excited to take to the skies to see what the instruments can do, although with the first battery of tests flown close to home in upstate New York, not all the instruments can be performance tested. If all goes well and the go-aheads are received, a trip to Greenland is planned for later in the spring to allow full instrument testing in true polar conditions.
To learn more about the Icepod project see: http://www.ldeo.columbia.edu/icepod/
For more on the Polar Geophysics Group: http://www.ldeo.columbia.edu/polar-geophysics-group/
Funding for this project from #ANT 0958658 under the MRI initiative.