NASA's Operation Ice Bridge, the largest airborne survey of Earth's polar ice ever flown, is in the midst of its third field campaign from Punta Arenas, Chile. The six-year mission will yield an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice.
Pine Island Glacier last calved a significant iceberg in 2001, and some scientists have speculated recently that it was primed to calve again. But until an Oct. 14 IceBridge flight of NASA's DC-8, no one had seen any evidence of the ice shelf beginning to break apart. Since then, a more detailed look back at satellite imagery seems to show the first signs of the crack in early October.
While Pine Island has scientists' attention because it is both big and unstable – scientists call it the largest source of uncertainty in global sea level rise projections – the calving underway now is part of a natural process for a glacier that terminates in open water. Gravity pulls the ice in the glacier westward along Antarctica's Hudson Mountains toward the Amundsen Sea. A floating tongue of ice reaches out 30 miles into the Amundsen beyond the grounding line, the below-sea-level point where the ice shelf locks onto the continental bedrock. As ice pushes toward the sea from the interior, inevitably the ice shelf will crack and send a large iceberg free.
"We are actually now witnessing how it happens and it’s very exciting for us," said IceBridge project scientist Michael Studinger, Goddard Space Flight Center, Greenbelt, Md. "It’s part of a natural process but it’s pretty exciting to be here and actually observe it while it happens. To my knowledge, no one has flown a lidar instrument over an actively developing rift such as this."
A primary goal of Operation IceBridge is to put the same instruments over the exact same flight lines and satellite tracks, year after year, to gather meaningful and accurate data of how ice sheets and glaciers are changing over time. But discovering a developing rift in one of the most significant science targets in the world of glaciology offered a brief change in agenda for the Oct. 26 flight, if only for a 30-minute diversion from the day's prescribed flight lines.
The IceBridge team observed the rift running across the ice shelf for about 18 miles. The lidar instrument on the DC-8, the Airborne Topographic Mapper, measured the rift's shoulders about 820 feet apart (250 meters) at its widest, although the rift stretched about 260 feet wide along most of the crack. The deepest points from the ice shelf surface ranged 165 to 195 feet (50 to 60 meters). When the iceberg breaks free it will cover about 340 square miles (880 square kilometers) of surface area. Radar measurements suggested the ice shelf in the region of the rift is about 1,640 feet (500 meters) feet thick, with only about 160 feet of that floating above water and the rest submerged. It is likely that once the iceberg floats away, the leading edge of the ice shelf will have receded farther than at any time since its location was first recorded in the 1940s.
Veteran DC-8 pilot Bill Brockett first flew the day's designed mission, crisscrossing the flow of the glacier near the grounding line to gather data on its elevation, topography and thickness. When it came time to investigate the crack, Brockett flew across it before turning to fly along the rift by sight. The ATM makes its precision topography maps with a laser than scans 360 degrees 20 times per second, while firing 3,000 laser pulses per second. When flying at an altitude of 3,000 feet, as during this flight, it measures a swath of the surface about 1,500 feet wide. As the crack measured at more than 800 feet wide in places, it was important for Brockett to hold tight over the crevasse.
"The pilots did a really nice job of keeping the aircraft and our ATM scan swath pretty much centered over the rift as you flew from one end to the other," said Jim Yungel, who leads the ATM team out of NASA's Wallops Island Flight Facility in Virginia. "It was a real challenge to be told…we’re going to attempt to fly along it and let’s see if your lidar systems can map that crack and can map the bottom of the crack.
"And it was a lot of fun on a personal level to see if something that you built over the years can actually do a job like that. So, yeah, I enjoyed it. I really enjoyed seeing the results being produced."
While the ATM provided the most detailed measurements of the topography of the rift, other instruments onboard the DC-8 also captured unique aspects. The Digital Mapping System, a nadir-view camera, gathered high-definition close-ups of the craggy split. On the flight perpendicular to the crack, the McCORDS radar also measured its depth and the thickness of the ice shelf in that region.
Catching the rift in action required a bit of luck, but is also testimony to the science benefit of consistent, repeated trips and the flexibility of a manned mission in the field.
"A lot of times when you’re in science, you don’t get a chance to catch the big stories as they happen because you’re not there at the right place at the right time," said John Sonntag, Instrument Team Lead for Operation IceBridge, based at Goddard Space Flight Center. "But this time we were."Patrick Lynch
Adam Voiland | EurekAlert!
Rare Earth Elements in Norwegian Fjords?
06.08.2020 | Jacobs University Bremen gGmbH
Rock debris protects glaciers from climate change more than previously known
05.08.2020 | Northumbria University
Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.
Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...
An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.
Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...
Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...
“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.
Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...
An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.
Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...
23.07.2020 | Event News
21.07.2020 | Event News
07.07.2020 | Event News
06.08.2020 | Earth Sciences
06.08.2020 | Power and Electrical Engineering
06.08.2020 | Life Sciences