Oct. 21, 1999 For 18 days during the Southern Hemisphere spring of 1997, a NASA-launched Canadian satellite called RADARSAT collected pieces of a puzzle that will help scientists study the most remote and inaccessible part of the Earth -- Antarctica. Scientists now have the puzzle pieces put together, forming the first high-resolution radar map of the mysterious frozen continent.
With detail to the point of picking out a research bungalow on an iceberg, the new map has both answered scientists' questions about the icy continent, and left them scratching their heads about what to make of strange and fascinating features never seen before.
In 1978, scientists predicted that global warming would lead to a disintegration of Antarctic Peninsula ice shelves. Spaceborne data indicate that this prediction may be coming true. In these before and after images, note the dramatic change in the apparent shoreline.
"This map is truly a new window on the Antarctic continent, providing new beginnings in our Earth science studies there," said Dr. Ghassem Asrar, Associate Administrator for Earth Science, NASA Headquarters, Washington, DC. The new map was produced as part of NASA's Antarctic Mapping Project.
The most amazing features scientists now see are twisted patterns of ice draining from the ice sheet into the ocean. "We were surprised to see a complex network of ice streams reaching deep into the heart of East Antarctica," said Kenneth Jezek, a glaciologist from the Byrd Polar Research Center at Ohio State University. Ice streams are vast rivers of ice that flow up to 100 times faster than the ice they channel through, with speeds up to 3000 feet per year. "There are some extraordinary ice streams in East Antarctica that extend almost 500 miles -- nearly the distance along the Mississippi River from New Orleans to Cairo, Illinois," Jezek said.
Ice streams form the most energetic parts of the Antarctic ice sheet, and scientists believe that they are quite susceptible to environmental change. Ice streams also transport most of the snow that falls on the continent's interior and dump it into the ocean.
"We've recently used RADARSAT and other satellite data to estimate that one ice stream system sends over 19 cubic miles of ice to the sea every year -- an amount equivalent to burying Washington, DC, in 1700 feet of ice every 12 months," said Jezek.
Antarctica looks pure, white and mostly featureless to the low-resolution satellites that previously mapped the frozen landscape. With the new RADARSAT map, however, the continent comes alive. Blocks of broken sea ice line the coast and sedimentary rock protrudes from the rocky walls of Antarctica's Dry Valleys. The vast, perplexing Antarctic Ice Sheet flows and twists into the sea, volcanoes poke through the ice sheet and ice streams flow like rivers into the Southern Ocean. Even the tracks of wayward snow tractors on their way to inland stations are visible. "We have a new view of the entire southern continent. It shows us something about an extraordinary part of our world and how humans may be changing it -- on both local and global scales," said Jezek.
Jezek and his colleagues have been working to complete the enormous map since the Canadian Space Agency began the mission with a complex in-orbit rotation of the satellite. Researchers chose RADARSAT because its radar collects data day and night, through cloudy weather or clear. Such capability enabled the mapping to be completed in just 18 days, compared to the last satellite map of Antarctica which required images from five different satellites spanning a 13-year period from 1980 to 1994. Even at that time, parts of the continent remained obscured by cloud cover.
The map also depends on accurate ground measurements by scientists from many of the nations that study Antarctica. "The entire mission was conducted in a true spirit of international cooperation, and that is why it succeeded," said Verne Kaupp, NASA's Alaska SAR Facility Director and Chief Scientist.
RADARSAT-1 is owned and operated by the Canadian Space Agency (CSA). Its data is distributed and marketed by RADARSAT International, a Canadian company licensed by the CSA. "We at the Canadian Space Agency are very pleased to make this significant contribution to the international science community," said Dr. Rolf Mamem, Director General, CSA Space Operations Branch. "We are looking forward to the exploitation of these data for the benefit of all."
The Antarctic Mapping Mission is only one part of NASA's study of the frozen continent. NASA's study of the Antarctic is part of the Agency's Earth Science Enterprise, a dedicated effort to better understand how natural and human-induced changes affect our Earth's environmental system.
RADARSAT images of Antarctica are available on the Internet at: http://svs.gsfc.nasa.gov/imagewall/antarctica.html (a must place to visit for exciting images and captions of RADARSAT images of Antarctica)
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