The USGS Remote Sensing Technologies Project
Remote Sensing Technologies - Satellite
Landsat Data Gap Studies
Landsat Data Gap Background
The Landsat suite of satellites has collected the longest continuous archive of multispectral data of any land-observing space program. From the program’s inception in 1972 to the present, Landsat data has been a valuable resource for monitoring global change and the use of Earth observations in decision making tools benefitting society. In order to meet observation requirements at a scale revealing both natural and human-induced changes on the landscape, the Landsat program provides an inventory of the global land surface over time on a seasonal basis.
The Landsat program has surpassed three decades of imaging the Earth’s surface. Landsat 5 (L5), with the Thematic Mapper (TM) sensor, was launched on March 1, 1984, and continues to perform well past its design life of three years. Nevertheless, the instrument has aged and its characteristics have changed since launch. Currently, the TM sensor has no capability to record and re-broadcast acquisitions and its duty cycle has been reduced.
Landsat 7 (L7), with the Enhanced Thematic Mapper Plus (ETM+) sensor on board, was launched on April 15, 1999, with a design life of five years. Although a Scan Line Corrector (SLC) failure occurred on May 31, 2003, L7 is still acquiring global coverage in a timely manner. It is likely, and expected, that either or both satellites could systematically fail completely or run out of fuel before the launch of the Landsat Data Continuity Mission (LDCM), planned for mid-2011.
No other domestic or international satellite program, current or planned, has the onboard recording capacity, direct-downlink receiving station network, and archive/production systems to routinely perform the full Landsat mission. If Landsat 5 and Landsat 7 fail before the launch of LDCM, there will be no direct replacement available for the Landsat data stream entering the Department of the Interior’s (DOI) U.S. Geological Survey (USGS) National Satellite Land Remote Sensing Data Archive (NSLRSDA) in Sioux Falls, S. Dak. A data gap will interrupt a 35+ year time series of land observations.
Landsat Data Gap Study Team
Federal agencies responsible for Landsat Program Management, National Aeronautics and Space Administration (NASA), and DOI USGS recognized the possibility of a data gap and convened a Study Team beginning in early 2005. The team recognized that, although no current or near-future satellite system could fully replace the Landsat satellites, capturing and archiving data from comparable systems could reduce the impact of a data gap. The team assessed the characteristics of multiple systems and identified sensors aboard India’s ResourceSat satellite and the China Brazil Earth Resources Satellite (CBERS) as the most promising sources of Landsat-like data. More in-depth technical evaluations of the data and capabilities of these systems are required before mission gap mitigation strategies can be fully formulated. The findings of the Study Team were presented to representatives of Office of Science and Technology Policy (OSTP) and Office of Management and Budget (OMB) on June 15, 2005.
An interagency Data Characterization Working Group (DCWG) was formulated to coordinate and leverage expertise from the technical staffs at three field centers, the NASA Goddard Space Flight Center (GSFC), NASA Stennis Space Center (SSC), and the USGS Earth Resource Observations and Science (EROS) Center, along with several collaborating universities. The aim was to perform an initial data quality assessment of image products acquired from foreign systems having the potential to mitigate an expected Landsat Mission data gap.
Landsat Data Gap Requirements
The Landsat Data Gap Study Team defined a set of minimum data-acceptance criteria for these sources, which would most likely replace only a portion of the Landsat data stream during a pre-LDCM data gap.
1Acquired data must be characterized and verified against these specifications to ensure data quality and continuity.
2Landsat/LDCM bands given; show and discuss any differences from these nominal bandwidths.
3NIR bandwidth given for LDCM; Landsat bandwidth of 780-900 nm is also acceptable.
This page lists documents directly related to the Landsat Data Gap Studies.