Landsat-7 Long Term Acquisition Plan Radiometry—Evolution over Time

Brian Markham , NASA Goddard Space Flight Center

Samuel Goward, University of Maryland College Park

Terry Arvidson, Lockheed Martin

Julia Barsi, Science Systems & Applications, Inc.

Pat Scaramuzza, SAIC

 

Photogrammetric Engineering & Remote Sensing, vol. 72, no. 10, pp: 1129–1135.

The Landsat-7 satellite acquires imagery of the Earth's land surface at a level of detail where the impacts of human activity can be monitored, for example, clearing and revegetation of forested areas. The imaging instrument on Landsat-7, the Enhanced Thematic Mapper Plus (ETM+) has a limit on the amount of information it can store on any one image or picture element (pixel) from which the image of the ground is formed. This limitation forced a compromise between the fineness of the detail that can be stored and the range of brightnesses that can be observed without saturation. A switch was built into the ETM+ instrument that allowed selection of finer detail or greater range for any given acquisition. Over the life of the mission, planners have developed various strategies to try to effectively use this switch. Flipping the switch introduces some short lived blips in the data, so it needs to be done sparingly. Also, different users have preferences for better precision or better range, so no totally satisfactory solution was achieved. The preferred solution for future missions is to increase the limit on the amount of information that can be stored per pixel.