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Landsat 7 Used To Map Antarctica in Unprecedented Detail

WASHINGTON —


An international team of researchers working with imagery collected over a three-year period by NASA’s Landsat 7 satellite has pieced




together what the agency says is the most geographically accurate and detailed map of Antarctica ever made.



The Landsat Image Mosaic of Antarctica was an 18-month project that sought to enable better research of the world’s coldest and most isolated continent. The true-color, high-resolution mosaic was made available to the public for free Nov. 27.

NASA, the U.S. Geological Survey and the British Antarctic Survey collaborated in




selecting 1,100 images to use from a pool of 22,000 taken by Landsat 7 between 1999 and 2001. The




scenes were processed for color accuracy and arranged into a nearly seamless, cloudless mosaic. The National Science Foundation contributed




roughly $1 million for the project.



The entire continent was mapped at




15-meter-resolution




with the exception of a spot at




the South Pole that the satellite’s orbit misses. The best previous map of Antarctica, stitched together from images taken by NASA’s Aqua and Terra satellites, has a resolution of 150 meters, NASA said




.





The Landsat-based map




totals 100 billion pixels, with each feature




geospatially accurate to within




50 meters. Project leader




Robert Bindschadler likened the undertaking to painting on a wall with a thousand little jars of white paint and coming up with a smooth and even color at the end. Bindschadler is chief scientist of the Hydrospheric and Biospheric Sciences Laboratory at NASA’s Goddard Space Flight Center, Greenbelt, Md.

“It’s a scientifically valid data set, not just a pretty picture,” Bindschadler said in a Dec. 5 interview




. “So we can say this is accurate, all 100 billion pixels.”

The NASA-built Landsat 7 has been in orbit for eight years, the newest in the series of




Earth-observing satellites that started launching in 1972. The program




now is managed by the U.S. Geological Survey.





In conceptualizing the project, Bindschadler thought a better map of the continent would encourage




more research there and a greater public understanding of the importance of that research.



“I want this to be a means [by]




which people connect with Antarctica and become more familiar with it and appreciate it,” he said. “They won’t value it unless they are more familiar with it. And they need to be, because that stewardship is going to be very important for the future.”

Planning research expeditions to Antarctica always has been difficult because most of the continent has never fully been surveyed from the




ground. The mosaic’s high resolution will allow researchers to better interpret changes in land elevation and help geologists better understand the unique rock structures there. Being able to see the continent like never before




also will help “get the scientific juices flowing to help propose good scientific questions,” Bindschadler said.



The images show




places that




very few, if any,




humans have ever seen,




many of them




far more beautiful and interesting than one would imagine, Bindschadler said.

“I’ve been impressed with how beautiful the continent is,” he said. “It’s stunning, and I wasn’t prepared for that. I think we have surprised ourselves with how effective the data set is with bringing the continent to life. For the first time, we can show anyone what Antarctica looks like.”

Changes in the Antarctic landscape can be seen around the edges of the continent in just the three years during which the Landsat images were collected.




The biggest changes




are around the Antarctic Peninsula, which stretches toward the southern tip of South America. Large ice shelves have disappeared there in only a matter of weeks.

“It won’t be until the next ice age that those come back,” Bindschadler said.



The next satellite in the series, the Landsat Data Continuity Mission, is scheduled to launch in July 2011. It will have a similar resolution to Landsat-7, with the addition of two more spectral bands.




It




also will be the first Landsat capable of pointing off-nadir, according Roz Brown, spokeswoman for Ball Aerospace, prime contractor for the satellite’s main instrument. The ability to tilt up to 15 degrees in any direction, instead of always facing straight down, will enable this satellite to better detect change in Antarctica and elsewhere, as it effectively shortens the satellite’s revisit time.