For Landsat Observations, Data Continuity Remains Key
SAN FRANCISCO — Scientists eagerly awaiting the scheduled launch in early 2013 of the next Landsat moderate-resolution land imaging satellite stressed the importance of continuing the data records with future spacecraft during a Nov. 16 press briefing.
Since 1972, the U.S. Landsat program has provided an invaluable tool for monitoring changes in global agriculture, reduction in worldwide forests, floods, fires and the spread of urban areas, according to a panel of scientists attending the William T. Pecora Remote Sensing Symposium in Herndon, Va. That data record will be extended by the Landsat Data Continuity Mission (LDCM), which originally was set to launch in December 2012 but is now likely to fly sometime between Jan. 15, 2013 and Feb. 15, 2013 due to a crowded launch manifest at Vandenberg Air Force Base in California, said James Irons, LDCM project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
The U.S. Congress has not provided NASA or the U.S. Geological Survey (USGS) with funding for additional missions.
“Past the Landsat Data Continuity Mission, there are no plans, there is no authorization from Congress, to move forward with Landsat 9 or anything beyond that,” said Curtis Woodcock, team leader for the USGS Landsat Science Team and a Boston University professor. “We are setting ourselves up to, sometime down the road, run into the situation where we no longer have the observations we need to continue to track the way the planet is changing.”
U.S. President Barack Obama requested $99.8 million in the 2012 budget to establish the National Land Imaging Program within the Interior Department’s USGS. That budget included funds to extend current USGS land imaging programs, upgrade Landsat ground stations in preparation for LDCM and initiate the Landsat 9 program. Congress has not yet approved a 2012 budget for the Interior Department.
Although LDCM is likely to launch in 2013, the spacecraft is on schedule to be fully assembled and tested by Dec. 1, 2012, Irons said. Ball Aerospace & Technologies Corp. of Boulder, Colo., has completed construction of one of the satellite’s two sensors, the Operational Land Imager instrument, which is designed to gather data in nine shortwave spectral bands with resolution of at least 30 meters. That sensor has been delivered to prime contractor Orbital Sciences Corp.’s Satellite Manufacturing Facility in Gilbert, Ariz. NASA Goddard has completed assembly of the second instrument, the Thermal Infrared Sensor, which is designed to collect images in two thermal bands. That instrument is undergoing environmental testing and is scheduled to be delivered to Orbital Sciences by Jan. 26, 2012, Irons said.
For years, scientists have been concerned that the LDCM would not reach orbit in time to prevent gaps in Landsat’s Earth observation data records. The two missions currently orbiting, Landsat 5 and Landsat 7, exceeded their anticipated life spans long ago. Landsat 5, a satellite launched in 1984 and designed to last at least three years, recently stopped acquiring images due to a rapidly degrading electrical component, the USGS said Nov. 18. Engineers have been wrestling with the problem for months but decided in recent days to suspend imaging operations for 90 days in order to explore options for restoring satellite-to-ground image transmissions, the USGS said. Landsat 7 was launched in 1999 and was expected to perform its mission for at least five years. That satellite continues to obtain data with its primary instrument, Enhanced Thematic Mapper Plus, but the spacecraft has been without a working scan line corrector since 2003, resulting in degraded imagery. After it is launched, the LDCM is scheduled to undergo approximately 90 days of testing and calibration before it begins to produce operational data, Irons said.
Scientists attending the Nov. 16 Landsat briefing stressed the importance of the LDCM and follow-on missions by providing examples of the contributions made by the Landsat program. Woodcock pointed to the United Nations Framework Convention on Climate Change, an international treaty signed in 1992 to limit the rise of average global temperatures. The dozens of countries who signed that agreement have been struggling for years to reach agreement on efforts to reduce carbon dioxide emissions produced by burning fossil fuels. However, the same countries have made great progress in drafting plans to offer incentives to countries to reduce greenhouse gas emissions produced by deforestation and forest degradation. “The whole idea wouldn’t even be possible if it weren’t for Landsat,” Woodcock said. Landsat provides a way to verify information provided by individual countries on deforestation and forest degradation, he added.
Landsat data also has enabled a group of European and sub-Saharan African researchers to make significant progress in measuring important changes in land cover, said Alan Belward, leader of the Global Environment Monitoring Unit at the Institute for Environment and Sustainability at the European Commission’s Joint Research Center in Italy. Based on Landsat observations of 2,000 sample sites, the researchers have learned that since the 1970s, approximately 50,000 kilometers per year of land previously covered by natural vegetation has been transformed into agricultural land in sub-Saharan Africa. At the same time, the population in the 30 sub-Saharan African countries being studied has more than doubled. As a result, there is now less agricultural land per person than there was in the 1970s, Belward said. That population growth creates continual demand for food and wood used for fuel.
“This process of deforestation is not going to stop any time soon,” he said. “So the monitoring and measuring shouldn’t stop.”