In a July 28th letter to the Honorable Gale Norton, Secretary, U.S. Department of the Interior, American Society for Photogrammetry and Remote Sensing (ASPRS) Executive Director James R. Plasker sought the Interior Secretary’s assistance to ensure that the U.S. Department of the Interior and the U.S. Congress would remain steadfast in their support of Landsat 7, an important land remote sensing program. “Since 1972, Landsat satellites have provided a continuous flow of moderate resolution, multispectral images of the Earth’s land masses vital to land planners, resource specialists and researchers in a wide range of disciplines,” noted Plasker. “As a result of recent malfunctions of the imaging sensor on-board Landsat 7, ASPRS is seriously concerned about both the future of this critical resource and the nation’s Landsat Program.”
In the letter, Plasker pointed out that the 31-year series of Landsat satellites has unquestionably been the most successful long-term land remote sensing system deployed by the U.S. or any other space-faring nation. Landsat 7 is critically important to the disciplines of agriculture, geology, hydrology, forestry, range management, geography, and many others. “The images are used to monitor global crop status and predict yields, map environmental conditions for defense/intelligence purposes, assess rates of deforestation and reforestation, map vegetation types, monitor land cover changes, plot wildfire boundaries and assess post-fire burn severity, monitor glacier movement, map coral reef decline, and support other applications that are too numerous to name in this letter,” he explained.
“We understand there is a serious debate occurring within the government as to the benefits of continued operation of a degraded Landsat 7 satellite. ASPRS members who utilize Landsat 7 data know with certainty that they cannot rely on the limited capabilities of the aged Landsat 5 (19 years in orbit) or inferior foreign satellite systems in the absence of a steady flow of global coverage from Landsat 7, even in a degraded mode,” Plasker said.
He requested Norton’s personal support and intervention to ensure that the U.S. Geological Survey (USGS) will continue to operate the Landsat 7 Mission Control Center and acquire 250 scenes per day (the standard daily data set) of degraded imagery for the foreseeable future. As the central portion of each image (covering a swath of about 20 miles wide and 100 miles long) is relatively unaffected by the sensor anomaly, Plasker stated he believes that this reduced coverage of a global data set is much better than no data at all. Considering that it will be three to four years before the launch of the next system -- the proposed Landsat Data Continuity Mission -- this interim decision is critical.
Further, Plasker said that he believes new data processing tools could be developed by the USGS, which would compensate for the remaining affected areas of each image, thus enabling even more uses of the currently degraded global data set. “However,” he warned, “in order to continue to be responsive to the scientific and resource management community, the USGS will need additional short-term funding support in order to continue Landsat 7 operations due to the recent fall-off in revenue from Landsat 7 data sales.”
A copy of the letter also was sent to Senate Appropriations Committee members Senator Ted Stevens and Senator Robert C. Byrd, House Appropriations Committee member Congressman Bill Young, and South Dakota Delegation members Senator Tom Daschle, Senator Tim Johnson, and Congressman Bill Janklow.
For additional information on the status of Landsat 7, visit http://landsat7.usgs.gov/updates.php.