Mission Mop Up

From: Kathryn Hansen, NASA’s Earth Science News Team / Cryosphere Outreach

April 8, 2011

Kangerlussuaq, Greenland — Today’s mission was a mix of the exciting and dull – from spectacular scenery over an ice cap, and up some glaciers and over Jakobshavn’s calving front, to the monotonous but scientifically important back-and-forth mapping of Russell glacier. It was essentially a “mop up” mission, combining targets from three separate flight plans.

We starting the day off flying over Sukkertoppen Isflade, our first ice cap of 2011! Flying over the blanket of ice, the scene abruptly ends as ice cascades down steep terrain into an open-water fjord that separates the ice cap from the Greenland Ice Sheet. Ice caps, while separate from the main ice sheet, are also undergoing changes and contribute to sea level rise.

An open-water fjord separates the Sukkertoppen ice cap from the Greenland Ice Sheet. Credit: NASA/Michael Studinger

Continuing south, we flew along several glaciers starting with Taserssuak (not thinning) and later on over Kangiatanunatasermia (thinning). The difference is interesting, as both glaciers are fed by the same fjord system. Scientists want to keep watch over these regions to continue to see how the change is changing.

We flew four glaciers fed by the Nuuk flord system including this glacier with a colorful name, Akugdlerssupsermia. Credit: NASA/Robbie Russell

After hitting some clouds as expected from the morning’s weather brief, we headed back north and reflew the center flow line of Jakobshavn — always spectacular — before flying over Illulisat Isfjord, which was surprisingly free of ice. The reason for the ice-free conditions was unknown to scientists onboard. There could have been fewer calving events, warmer water, or wind patterns that pushed ice out of the area.

“Half of the Illulisat Isfjord was open water with several fishing boats in the area, something I have never seen before,” said Michael Studinger, the mission’s project scientist.

A camera mounted on the belly of the aircraft captured this image of a fishing boat (top) in the Illulisat flord, which was mostly open water with a few visible patches of ice. Credit: NASA/DMS team

Next it was on to Russell Glacier, just outside of our home base, Kangerlussuaq. Back and forth, this was a true “moving the lawn” pattern. I may have even taken a brief nap. But to scientists, this mapping is critical. A radar instrument onboard will get a good look at what’s below all that ice and help scientists better understand how the bedrock influences the flow of glaciers.

Battling the Arctic Chill

From: Kathryn Hansen, NASA’s Earth Science News Team/Cryosphere Outreach

April 6, 2011

Kangerlussuaq, Greenland — It may seem obvious, but the Arctic is cold. I was surprised to arrive in Kangerlussuaq, Greenland, to see the hills and streets covered with snow and temperatures that make you second-guess the wisdom of leaving any skin exposed.

In 2010, the Kangerlussuaq leg of Operation IceBridge began about a month later, in May. What a difference a month makes. The hills were snow-free, flowers beginning to bloom, days were long, and the river rushed to break up the last chunks of winter ice. On down days, crew and science teams hiked, biked and went fossil hunting. Now we mostly stick to the warm indoors. Most of us, however, are willing to brave the cold and dwindling hours of darkness to catch a spectacular show of the northern lights.

This time lapse of the northern lights consists of 30-second exposures spanning just over an hour. We took turns behind the camera, running inside every 15 minutes to quickly warm up. Credit: NASA/Jefferson Beck

It turns out that the aircraft also battles the cold. On April 5, we planned to fly the mission’s first science flight from Kangerlussuaq to collect data over Jakobshavn — Greenland’s fastest moving glacier. At 6 a.m. it was just -11 F. The coffee pot onboard froze and fractured.

Shortly after take off, the cold temperatures resulted in a mechanical issue on the aircraft that forced an early return to Kangerlussuaq, Greenland. The P-3’s adept aircrew was quick to diagnose and resolve the issue.

John Doyle, a P-3 flight mechanic, is on the aircraft early and prepared for the cold. Credit: NASA/Kathryn Hansen

On April 6, crew started the day extra early at 5:30 a.m. when the temperature measured in even chillier at -18 F. Additional heating for an extended period prior to flight led to a successful first flight from Kangerlussuaq. And what a spectacular, clear flight.

The DMS, a downward looking camera system, captured this shot of Jakobshavn’s calving front. Credit: NASA/DMS team

Instrument teams onboard the P-3 also battle with the effects of temperature. Scientists with the laser altimeter use hair dryers to warm up the instrument, but too hot is also problematic. Scientists working with the radar instruments prefer the cooler time of year before melt ponds appear on the ice, complicating the way light reflects from the surface.

Having overcome challenges posed by the cold, we’re looking forward to a long series of land ice flights over Greenland. There’s word among the crew that the new coffee pot should arrive in a few weeks, in time for IceBridge’s return to Thule. Thanks to the P-3 crew for what might be the best cup of Joe in Greenland!

In the absence of coffee pot, P-3 crew construct a makeshift filter out of a water bottle. Credit: NASA/Kathryn Hansen

A Five-Hour Survey

From: Kathryn Hansen, NASA Earth Science News Team / Cryosphere Outreach

April 3, 2011

Colors show elevation differences across the airport’s ramp in Kangerlussuaq, Greenland. The map is used to calibrate airborne instruments. Credit: NASA/ATM team

Kangerlussuaq, Greenland — During the last IceBridge campaign, based in Punta Areans, Chile, we described a three-hour ramp survey. Scientists drove a truck with a GPS antenna affixed to the roof to map the precise elevation of the airport’s entire ramp — the pavement next to the runway where the aircraft spends each night. The ramp map helps researchers calibrate science instruments on the aircraft.

Here in Greenland, at Kangerlussuaq International Airport, the same activity on Saturday, March 3, would turn into a five-hour survey.

“This has to be the biggest ramp in the world,” said Kyle Krabill who drove the car, bringing me along as the unsuspecting passenger.

The task started that morning after idling for an hour on the ramp to calibrate the GPS. Then, we rolled off at a whopping 15 miles per hour, windows rolled down and 80’s Danish music blaring. Back … and forth … and back … and forth … we traced around the perimeter of the ramp and then inward, as if we were mowing a lawn of pavement.

A time lapse shows one hour of four-hour-long ramp survey. Video credit: NASA/Jefferson Beck

“See how easy it is to be a scientist?” Krabill joked. But it turns out that driving the car is just the beginning.

Krabill is part of the team that runs the Airborne Topographic Mapper (ATM), an instrument flying with IceBridge. ATM pulses laser light in circular scans on the ground. The pulses reflect back to the aircraft and are converted into elevation maps of the ice surface.

Toward the end of each flight, ATM laser elevation data are also collected during a pass over the ramp. Putting the data all together (including the dizzying ground-based ramp survey), and knowing the precise location of the aircraft (via a technique called “differential GPS”) scientists can decipher and eliminate some of the inherent error that comes with flying a laser scanner, such as errors in range — the physical distance to the ground — and in the team’s knowledge of the way in which the scanner is mounted in the aircraft.

“Differential GPS is fundamental to what we do,” said John Sonntag, ATM senior scientist. “It’s tremendously powerful, taking position error down from about 10 meters to 10 centimeters or better — a huge improvement.”

P-3 Back in Service

April 2, 2011

Kangerlussuaq, Greenland — The P-3 is ready to return to IceBridge just 30 hours after the aircraft’s prop valve failed on Friday, April 1. Here we list highlights from the tremendous effort by aircraft crew who were responsible for the speedy return to flight.

P-3 crewmen John Doyle and Brian Yates work on engine #2. Credit: NASA/Jim Yungel

Friday morning:

1. From Kangerlussuaq, Greenland, get permission to ferry the aircraft to its home in Wallops Island, Va.

2. Line up customs at Dover Air Base

3. File a flight plan

4. Fuel the aircraft

Friday night:

5. Remove the propeller on engine #2

Saturday morning:

6. Replace the P-3 propeller valve

7. On the ramp, let the aircraft’s engine run

8. Functional checkout flight (successful!)


9. Take a much-deserved mandatory hard down day in Wallops Island, Va.


10. The P-3 is scheduled to depart Wallops at 7 a.m. EDT and arrive in Kangerlussuaq at 4:30 p.m. local time, ready for a possible flight on Tuesday!

Engine run up under way on the ramp at Wallops. Credit: NASA/Jim Yungel

LVIS is in the Building

From: Kristyn Ecochard, NASA’s Langley Research Center

Crewmembers are busy getting the B-200 King Air at NASA’s Langley Research Center in Hampton, Va. ready for its first flight with Operation IceBridge.

The King Air will be carrying the Land Vegetation and Ice Sensor (LVIS) onboard for several weeks of science flights over the Arctic. LVIS is an instrument from NASA’s Goddard Space Flight Center in Greenbelt, Md.

Engineers are uploading the instrument and other science equipment in preparation for a scheduled departure date of April 13.

IceBridge teams are already in Greenland conducting science flights onboard the P-3B based out of NASA’s Wallops Flight Facility in Wallops Island, Va.

The B-200 King Air at NASA’s Langley Research Center is a small plane that can get up to 35,000 feet. Credit:NASA/Sean Smith

The King Air will only carry one instrument on its science flights over the Arctic: the Land Vegetation and Ice Sensor (LVIS) operated by NASA Goddard Space Flight Center’s David Rabine and Shane Wake. Credit:NASA/Sean Smith

NASA Goddard Space Flight Center’s Land Vegetation and Ice Sensor (LVIS) will map large areas of sea ice and glacier zones. Credit: NASA/Sean Smith

Keeping Us On Track

From: John Sonntag, ATM Senior Scientist and IceBridge Instrument Team Lead

Thule, Greenland — One of the many unusual aspects of flying with NASA’s Operation IceBridge (OIB) is that we fly very, very precisely. Getting the airplane where we want it to be, when we want it to be there is important for a variety of reasons. At its most basic, however, precise flying is necessary to match the limited footprint of our remote-sensing instruments with the target they are measuring. This target might be a spacecraft ground track, the centerline of the fastest-moving channel of a steep, sinuous glacier, or even a research camp established on a drifting ice floe.

Our pilots are outstanding professionals and the precise flying is primarily their doing. But to help them do it, OIB leverages NASA’s multi-decade investment in operations of the Airborne Topographic Mapper (ATM), a scanning lidar and key instrument of OIB. The ATM project, which is my own home team and where I learned most of what I know about airborne science, long ago addressed the need to fly a remote-sensing aircraft very accurately over regions with no fixed landmarks. The key, not surprisingly, is the Global Positioning System, or GPS. GPS, of course, gives us nearly continuous updates of our position with an accuracy of just a few meters. But using this knowledge effectively, especially at 250 knots, is a little tricky.

So the ATM team developed, and continues to modernize, a suite of software and hardware tools to effectively use GPS to help pilots steer an airplane very accurately, and even to steer the airplane directly. In their current form these tools are called “SOXMap and SOXCDI”.

SOXMap is really just a “moving map” system, at heart not unlike the ones in consumer GPS units used in cars or for hiking, but simpler and highly specialized for remote sensing applications. SOXMap displays the aircraft’s current position and orientation relative to a science target, such as the sinuous centerline of a glacier (see the SOXMap illustration, left). It also displays the measurement swath being collected by a science instrument such as the ATM, drawn to scale. This display is piped to the pilots up front, using little tablet computers with very sharp, bright displays, which are mounted right on the control yoke. Our pilots use this information, which is continuously updated, to steer the aircraft and its sensor swath right where we want it. Some of our OIB pilots refer to SOXMap as “the Pac Man display”, in reference to the old video game where the player guides a little mouth around a screen chewing up dots. The beauty of SOXMap is its versatility. Our bread-and-butter use for it with OIB is to follow sinuous glacier centerlines with any degree of curvature, but SOXMap is also useful for area-mapping applications, or really any targeted flying.

Even cooler than SOXMap is its sibling, “SOXCDI”. SOXCDI (image right) incorporates a moving map display similar to the one in SOXMap, but unlike SOXMap, SOXCDI can actually steer the airplane automatically! It is designed for cases where we fly long straight lines, such as grid lines or satellite ground tracks. We can do the same thing successfully using only SOXMap, but for long straight lines this demands lengthy periods of concentration from our pilots and can be extremely tedious for them. So SOXCDI continuously compares the current position of the aircraft to a desired straight-line track connecting a pair of waypoints (for any navigation geeks who might be reading along, the straight line is actually a great circle, and I plan to add a selectable rhumb line option as well). Doing a little math with that comparison, we always know how far we are from the desired track and whether we are right or left of it.

But how do we use this information to steer the aircraft automatically? Here is where things get extremely cool. It turns out that most large airplanes have what is called an “instrument landing system”, or ILS. The ILS is really just a radio receiver that is designed to listen to a simple pair of audible tones being broadcast from an airport runway, each tone angled slightly away from each side of the centerline. This allows them to land in bad weather when the runway isn’t immediately visible. If the ILS radio “hears” more of one of the tones than the other, it directs the pilot, actually the autopilot in our case, toward the “quieter” tone until the two tones are equal. When they are equal, the airplane is centered on the runway, right where it should be.

Can you guess where we’re going here? SOXCDI simply mimics an ILS signal, which we pipe into the aircraft’s autopilot. And it’s pretty simple, really. If we’re left of track, we generate more of the “left” tone than the “right” tone, and vice versa. The airplane’s autopilot does the rest. The tricky part comes in calculating how much of each tone we generate given how far right or left of track we are, but those are just details. The point is, the system is simple because we just piggyback on existing technology – the ILS. And though our software certainly has some complexity, the hardware is almost breathtakingly simple. We run the SOXCDI (and SOXMap) programs on very basic, run-of-the-mill computers – that 8-year-old laptop you tossed in the closet during the previous presidential administration would probably work fine once we installed our software on it. The tones are generated by the sound card built in to every modern computer has built in. We literally just plug a cable into the headphone jack of the computer, and plug the other end into a standard piece of lab equipment called a “function generator.” The function generator just takes the two tones and turns them into a radio signal, which we then pipe via another cable into the airplane’s ILS. And that’s it. You might not be familiar with a function generator, but to give you an idea what a basic piece of lab equipment it is, we recently bought one for just about $1,000, about what a basic laptop costs.

Once it’s all set up, SOXCDI generally keeps the airplane within just a few meters of where we want it to be, and can do it literally all day long. It does this, in essence, by “singing” a two-note chord to the airplane, the relative volumes of the two notes determining the steering correction. And it works equally well with both of NASA’s workhorse OIB airplanes – the P-3 turboprop and the DC-8 jet. And that points to another strength of the SOXCDI design. Because it mimics standard ILS signals, it should work with any ILS-equipped airplane.

If I sound enthusiastic about our precise navigation systems, well, I am. I am the developer of SOXMap and the co-developer of SOXCDI with my colleague Rob Russell, and I’m very proud of their role as a key enabling technology for IceBridge. They are also just about the most fun projects I’ve ever taken on at work, a perfect task for an at-heart aerospace tinkerer like me. But Rob and I can’t claim all the credit, or even most of it. We built SOXCDI and SOXMap on ideas originally conceived and developed by our colleagues Wayne Wright (SOXCDI predecessors), and Richard Mitchell and Bob Swift (SOXMAP predecessors), respectively.

And finally, what about those names? Well, the original implementation of the moving map concept with the sensor swath drawn to scale, way back in the 90s, was called XMAP. So in homage to that, I originally called my implementation “Son Of XMAP”, which became SOXMap. Later when we developed SOXCDI, we essentially merged elements of SOXMap and and older system called CDI (for Course Deviation Indicator), yielding SOXCDI.

Weathering the Storm

Spring officially arrived on Sunday, but for IceBridge scientists in Thule, Greenland, spring was nowhere to be seen. Teams awoke Monday to a storm that continued through the day and by 5 p.m. local time, Thule Air Base had declared “Delta” status, prohibiting on-base travel and confining personnel to the buildings.

The storm on Monday in Thule intensified to “Delta” status. IceBridge scientists waited out the storm indoors. Credit: NASA/Jim Yungel

While snow blows outside, IceBridge project scientist Michael Studinger briefs the teams at the nightly meeting. A science flight the following morning would require clear skies. Credit: NASA/Jim Yungel

With no other options for food, some scientists turned to MREs (Meal, Ready-to-Eat), including this southwest style beef and beans with Mexican style rice, picante sauce, and chocolate disk cookie dessert. Credit: NASA/Jim Yungel

The ground-based GPS antennas did not fair as well in the storm, although both stations have since been reestablished and ready for a science flight. Credit: NASA/Kyle Krabill

By Tuesday morning the storm had passed and crews were quick to plow the runway. Credit: NASA/Jim Yungel

With a clear runway, the P-3 was rolled out for a long-awaited, high-priority sea ice flight to Fairbanks, Alaska. Credit: NASA/Jim Yungel

An Uncommon Routine

From: Michael Studinger, IceBridge project scientist, Goddard Earth Sciences and Technology Center at the University of Maryland, Baltimore County

Thule Air Base, Greenland — The IceBridge team arrived in Thule last week and the campaign is off to a good start. We flew four out of five days last week and accomplished three sea ice missions including an underflight of the European Space Agency’s CryoSat-2 satellite over the Arctic Ocean. After a week here in Thule, we are settled in and our operations have become routine.

Operation IceBridge accomplished three science missions during the first week, including an underflight of ESA’s CryoSat-2 over the Arctic Ocean just 120 miles from the North Pole. Credit: NASA

A typical IceBridge day in Thule Greenland starts at 5 a.m. when my alarm clock goes off. I start downloading satellite images to get an idea which missions may be possible to fly before I go to breakfast at 5:45 a.m. At 6:15 a.m., the pilot in command, mission manager, John Sonntag and myself meet at Base Ops to get a weather brief for the day.

The three meteorologists at Thule Air Base have known us for years and do an excellent job in providing us with a very detailed and specialized weather brief that we require for decision making. The demands for research flights are different from everyday air travel, and the polar environment poses great challenges in terms forecasting the weather. There is not a single weather station within hundreds of miles of our survey area that we could use to get a weather observation or that would provide observational data as input into a forecast model. Instead, we depend on satellite images that are several hours old. Visible images are dark for any area west of us. It requires experience and skill to interpret the forecast products for our purpose.

A few days ago, a model transect along our flight path showed dense cloud cover along the entire mission profile at 500 meters flight elevation calling for a no-fly day. We spent time with the meteorologists to understand the weather situation and decided to fly, despite the grim looking forecast. It was the right decision. The cloud layer depicted by the forecast model turned out to be a thin layer of haze that did not pose any difficulties for our laser and digital imagery sensors.

The weather forecast is shown along a survey line for a P-3 science mission. The forecast predicts dense cloud cover at the flight elevation (500 m), but after carefully studying the weather situation, we decided to fly. Credit: NASA

Between 6:30-6:45 a.m. we make a go/no-go decision. If we fly, the aircraft gets pushed out of the hangar and the fuel truck arrives. We need to collect one hour of static GPS data on the ground to calculate high-precision trajectory data from our flights. At 7:30 a.m. the door of the aircraft closes and we taxi to the runway to be ready for an 8 a.m. takeoff as soon as the tower opens.

We typically transit to the survey area north of Thule and then descend to 1,500 feet were we start collecting data. It’s still early in the season, which means missions west of Thule are flown in near-constant twilight, with the sun following us as we go west. When we turn around the western end of the line and fly back east, it immediately start getting lighter with every minute of the flight.

During the flight the operators monitor their instruments and make sure we collect high-quality data. Occasionally, adjustments need to be made to ensure the instruments keep working.

In-flight adjustments are often necessary to keep the instruments working and collecting high-quality data. Adjustments often require work below the deck to access the instrument sensors in the belly of the P-3. Credit: NASA/Michael Studinger

At 3:45 p.m. we typically land to leave enough time for a 1-hour post-calibration with the aircraft outside. By 5 p.m. the aircraft is rolled back inside the hanger and doors close for the night.

John Sonntag and myself quickly stop by Base Ops for another weather brief to see what’s in the mix for the next day. At 5:30 p.m. we have a science meeting where we discuss plans for the next day and talk about issues that are worth sharing with others. After the meeting, most people go straight to dinner followed by a late evening spent backing up data and processing data.

At 5 a.m. the next morning we start again.

A lateral moraine can be seen at the margin of the Greenland Ice Sheet near Thule Air Base. Credit: NASA/Michael Studinger

View From the Hut

We previously wrote about the Met Huts in Kangerlussuaq and Thule, Greenland –- the ground-based GPS stations that help scientists to ensure that GPS information collected on the aircraft is as accurate as possible. Kyle Krabill is back in Thule for the Arctic 2011 campaign making sure hut operations run smoothly.

From: Kyle Krabill, ATM Instrument Team Engineer, NASA’s Wallops Flight Facility

“Took a couple pictures this morning [March 17] from my view here at the hut. Sunrise is getting earlier by 13 minutes or so each day. The guys are flying another mission again today. Had a little warm front come through last night and its up to a balmy -17 (if you’re out of the wind)”

The P-3 passes over the Met Hut on March 17, 2011. Credit: Kyle Krabill

The sun rises in Thule, Greenland, as seen from the Met Hut on March 17, 2011. Credit: Kyle Krabill

Teacher, Student Blog From the Arctic

A teacher and student from the U.S. Naval Academy in Annapolis, Md., joined IceBridge in the field for the Arctic 2011 campaign. Follow their Arctic adventures here.

LCDR John Woods is a Meteorology and Oceanography Officer (METOC) currently teaching in the Oceanography Department at the United States Naval Academy (USNA). He is part of the Sea Ice Thickness Observation team currently participating in NASA’s Operation Ice Bridge 2011.

Eric Brugler is First Class Midshipmen who is an honors Oceanography major at the United States Naval Academy. He is interested in the polar regions of Earth because he believes they play a very important role to the Earth’s climate system.