David E. Steitz
Headquarters, Washington, DC                       Oct. 18, 1999
(Phone:  202/358-1730)

Allen Kenitzer
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-2806)

RELEASE:  99-122

NASA UNVEILS NEW, MOST ACCURATE MAP OF ANTARCTIC CONTINENT

     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.

     "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

                              -end-

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