NASA is currently conducting Operation Ice Bridge, a six-year campaign of annual flights to each of Earth’s polar regions designed to help scientists bridge the gap between NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) — which is operating the last of its three lasers — and ICESat-II, scheduled to launch in 2014. It is doing so by providing the needed data collected by researchers on board a DC-8, a 157-foot-long airborne laboratory and the largest aircraft in NASA’s airborne science fleet; one that accommodates many instruments.
Leading the current Antarctic campaign is principal investigator Seelye Martin of the University of Washington. It is the first sustained airborne research effort of its kind over the Antarctic continent and will help scientists maintain the record of changes to sea ice and ice sheets that have been collected since 2003 by ICESat. The flights will lack the continent-wide coverage that can be achieved by satellite, so researchers carefully select key target locations that they are approaching between October 12 and November 17, 2009.
Tom Wagner, cryosphere program scientist at NASA Headquarters in Washington, D.C. said:
“Space-based instruments like the ICESat lasers are the only way to find out where change is occurring in remote, continent-sized ice sheets like Antarctica. But aircraft missions like Ice Bridge allow us to follow up with more detailed studies and make other measurements critical to modeling sea level rise.
A remarkable change is happening on the Earth, truly one of the biggest changes in environmental conditions on Earth since the end of the ice age. It’s not an easy thing to observe, let alone predict what might happen next. Studies like this one are key.”
ICESat launched in January 2003 and since then, its sole instrument — a precise laser altimeter — has helped scientists map ice sheet elevation, calculate sea ice thickness, and monitor how both have changed, like the shifts in surface elevation have previously revealed the draining and filling of lakes below Antarctica’s ice.
After ICESat, scientists will rely on an airborne laser called the Airborne Topographic Mapper (ATM), developed at NASA Wallops Flight Facility in Wallops Island, Va. ATM pulses laser light in circular scans on the ground, and those pulses reflect back to the aircraft and are converted into elevation maps of the ice surface. By flying ATM over the same swath of ground covered by ICESat, researchers can compare the two data sets and calibrate them so that aircraft can continue the record keeping after the satellite data ends. They can also make more detailed elevation studies over dynamic areas, such as the Crane glacier on the Antarctic Peninsula, which sped up following the collapse of the Larsen Ice Shelf in 2002.
In addition, University of Kansas scientists will fly the Multichannel Coherent Radar Depth Sounder, which measures ice sheet thickness. It can also map the varied terrain below the ice, which is important for computer modeling of the future behavior of the ice.
The Laser Vegetation Imaging Sensor, developed at Goddard, will map large areas of sea ice and glacier zones. And a gravimeter, managed by Columbia University, will measure the shape of seawater-filled cavities at the edge of some major fast-moving major glaciers. Finally, a snow radar from University of Kansas will measure the thickness of snow on top of sea ice and glaciers, allowing researchers to differentiate between snow and ice and make more accurate thickness measurements.
The plane crew and researchers are based in Punta Arena’s and are traversing the Southern Ocean for up to 17 flights over West Antarctica, the Antarctic Peninsula, and coastal areas where sea ice is prevalent. Each round-trip flight lasts about 11 hours, two-thirds of that time devoted to getting to and from Antarctica.
The Antarctic continent may be remote, but it plays a significant role in Earth’s climate system. The expanse is home to glaciers and ice sheets that hold frozen about 90 percent of Earth’s freshwater — a large potential contribution to sea level rise should all the ice melt.
Compared to the Arctic, where sea ice has long been on the decline, sea ice in Antarctica is growing in some coastal areas. Snow and ice have been accumulating in some land regions in the east. West Antarctica and the Peninsula, however, have seen more dramatic warming and rapid ice loss.
Read the blog of each flight at NASA’s website.
Read the related story “Radar Reveals Dynamic World Under Antarctica’s Ice” at NPR.
Copyright © 2009 by Marine Science Today, a publication of OceanLines LLC