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Feb. 11, 2014
One of the first complete views of the United States from Landsat 8. Image Credit: NASA/David Roy
On Feb. 11, 2013, the Landsat 8 satellite rocketed into a sunny California morning onboard a powerful Atlas V and began its life in orbit. In the year since launch, scientists have been working to understand the information the satellite has been sending back. Some have been calibrating the data—checking it against ground observations and matching it to the rest of the 42-year-long Landsat record. At the same time, the broader science community has been learning to use the new data.
The map above—one of the first complete views of the United States from Landsat 8—is an example of how scientists are testing Landsat 8 data. David Roy, a co-leader of the USGS-NASA Landsat science team and researcher at South Dakota State University, made the map with observations taken during August 2013 by the satellite’s Operational Land Imager.
The strips in the image above are a result of the way Landsat 8 operates. Like its predecessors, Landsat 8 collects data in 185-kilometer (115-mile) wide strips called swaths or paths. Each orbit follows a predetermined ground track so that the same path is imaged each time an orbit is repeated. It takes 233 paths and 16 days to cover all of the land on Earth. This means that every land surface has the potential to be imaged once every 16 days, giving Roy two or three opportunities to get a cloud-free view of each pixel in the United States in a month.
Landsat's Orbit
Video above: In the year since its launch, Landsat 8 has made 5,319 orbits of Earth, capturing images of the land surface below. Here, Landsat 8 project scientist Jim Irons explains how those orbits capture the whole planet in 16 days. Image Credit: NASA's Goddard Space Flight Center.
Landsat 8 then joined its predecessor satellites to provide a continuous record of change across Earth's land surfaces since 1972.
Orbiting about 440 miles (705 km) above Earth, Landsat satellites document natural processes such as volcanic eruptions, glacial retreat, floods and forest fires, as well as human-induced processes such as urban expansion, crop irrigation and forest clear-cutting.
"Data produced by Landsat plays a vital role in managing America’s natural resources and the industries and jobs that rely on those resources," said Sen. Barbara Mikulski, chairwoman of the Senate Appropriations Committee that funds NASA and USGS. "It was Landsat that brought home the severity of Midwest floods in the 1990s, and it has helped identify periods of severe drought that were so devastating to our farmers and foresters. My hat goes off to NASA's Goddard Space Flight Center that has played a key role in building each of the Landsat satellites, including Landsat 8, improving each satellite with the latest technology and help us better understand planet Earth."
A high-flying rookie season
Landsat 8 is acquiring around 550 images per day – significantly more than the 400-image-per-day design requirement. Between Landsat 7 (launched in 1999 and still active) and Landsat 8, nearly 1,000 images per day are being collected. This is almost double the imagery collected three years ago, when Landsat 5 and 7 were operating together. The ability of Landsat 8 to image more frequently in persistently cloudy areas (e.g., humid tropics, high latitudes) is improving data collection in areas of critical importance for climate studies.
Landsat 8's robust data processing system also enables images to be available for public use within five hours of their arrival at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center in Sioux Falls, S.D. Since 2008, all Landsat data is free to all. Enhanced Landsat 8 data have quickly found their way into a wide range of operational applications, including forest health monitoring by the U.S. Forest Service, burn severity mapping by the USGS, NASA and the National Park Service, and cropland mapping by the National Agricultural Statistical Service.
"Before launch, I stated that Landsat 8 would be the best Landsat satellite yet — and I think the first year has proven that," said James Irons, Landsat 8 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Scientists are very pleased with the results. They can see more detail and can identify land cover more easily."
In land cover classification tests, conducted by Curtis Woodcock of Boston University, the Landsat 8 classification results were 19.5 percent more accurate than those developed from Landsat 7. Australian researchers are finding that improved Landsat 8 data have enhanced their ability identify and quantify areas of land degradation or improvement in the extensive Australian outback.
"Landsat 8's geometric and geodetic accuracy is so good that the USGS now has the means to use Landsat 8 data to significantly improve the geometric accuracy of the entire 4.6 million image Landsat archive," Tom Loveland, USGS-EROS senior scientist, noted. "That's a rare bonus — to be able to improve the historical record."
With the help of Landsat 8's thermal imagery, Ted Scambos and University of Colorado, Boulder, researchers found locations in eastern Antarctica that were several degrees colder than the -128.6 F (-89.2 C) record set in 1983.
A combined effort of two teams
During the past 12 months, the USGS-EROS Center and NASA Goddard have worked in close collaboration — putting the new satellite through its paces by steering it into its orbit, calibrating its detectors, collecting test images and certifying the mission for sustained operation.
As partners in the Landsat program since its inception in the 1960s, USGS and NASA have distinct roles. NASA develops remote-sensing instruments and spacecraft, launches the Landsat satellites and validates their performance. The USGS then assumes ownership and operation of the Landsat satellites, in addition to managing ground-data reception, archiving, product generation and distribution.
Artist concept of Landsat 8. Image Credit: NASA's Goddard Space Flight Center
"The Landsat archive, reaching back across four decades, provides an unprecedented record of land-surface change," said NASA Goddard Center Director Chris Scolese. "The Landsat program's success is largely due to the great partnership between NASA and the USGS. Every day we are building and strengthening that partnership, which will undoubtedly contribute to the success of future missions."
"NASA's successful development and launch of Landsat 8, the rapidly increasing volume of image data distributed by the USGS to research and operational users worldwide, and the administration's identification of Landsat as one of the nation's critical data streams – all of these factors have sparked renewed emphasis by the administration and the user community in securing uninterrupted access to Landsat data for decades to come," said USGS-EROS Director Frank Kelly. "Both NASA Goddard and the USGS-EROS Center have developed and maintained unique capabilities, where each center leverages on the strength and expertise of the other, avoiding duplication and ensuring the success of each mission."
NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.
For more information about NASA's Earth science activities in 2014, visit: http://www.nasa.gov/earthrightnow
For more information about Landsat 8, visit: http://www.nasa.gov/landsat; or http://www.landsat.gsfc.nasa.gov; or http://www.landsat.usgs.gov
Images (mentioned), Video (mentioned), Text, Credits: NASA's Goddard Space Flight Center / Kate Ramsayer / U.S. Geological Survey / Jon Campbell.
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