Monday, February 2, 2015

Landsat Sensor Performance: History and Current Status

The Thematic Mapper (TM) was designed in the late 1970s as the successor to the Multispectral Scanner Systems (MSS) used on Landsats (aka Land Satellites). The Thematic Mapper's design offered several improvements over the Multispectral Scanner Systems. However, since its design was significantly more complicated, there were concerns as to how well it would perform, leading to a NASA-funded Landsat Image Data Quality Analysis (LIDQA) study following the launch of Landsat-4 in July 1982. Landsat-5 (launched in 1984) was nearly a carbon copy of Landsat-4, with a few problems corrected that had been previously observed on its predecessor. In 1985, with the end of LIDQA, the majority of the published Landsat characterization work ceased. The United States Geological Survey (USGS) funded some studies aimed at improving the radiometric quality of TM data in 1990. Studies were started to correct some of the banding and striping artifacts in TM data. In 1992, Public Law 102-555 required the US Government to develop the Landsat-7 system (Landsat-6 was lost in a launch failure in 1993). From the initiation of the Landsat-7 system, greater attention was given toward the long-term characterization and calibration of data than earlier Landsats. As of early October 2004, both the Landsat-5 and the Landsat-7 continue to operate. However, the Landsat-5 has experienced degradation over the years, particularly in the scan mirror bumpers and the internal calibration lamps. Even though the Landsat-5 is operating well, data can only be directly downlinked to ground stations in view of the Landsat-5 spacecraft due to the original Tracking and Data Relay Satellite (TDRS) links not working anymore. The Landsat-7 has a permanent failure in its Scan Line Corrector (SLC) as of May 31, 2003. As shown in the picture, the SLC is stuck in one position, resulting in gaps and overlaps between successive scanned data. The radiometric and geometric properties of the data are otherwise unaffected, and thus the USGS restarted collection of data with the SLC turned off in late October of 2003. Beginning in 2004, the USGS started providing the first of a series of products in order to make the SLC-off data more usable.
Markham, B., Storey, J., Williams, D., & Irons, J. (2004). Landsat Sensor Performance: History and Current Status. In Geoscience and Remote Sensing (12th ed., Vol. 42, p. 2691,2694). IEEE Transactions.

No comments:

Post a Comment