Geomorphology from Earth Orbit 1957-2000

Abstract This chapter examines the technical capabilities of orbital earth observation sensors and considers associated geomorphic user requirements between 1957-2000. Early photography from space provides much promise which is followed by successive dedicated satellite missions. These produce data at ever greater spatial and spectral resolution as well as frequency starting with Landsat 1 in 1972. Users especially in the arid and polar community are drawing on this new technology. However, the wider uptake of data derived from passive systems such as Landsat and other such sensors by geomorphologists is sporadic, due to the mismatch between data requirements and systems specifications. Limitations to most geomorphologists would have included data cost, given that even Landsat data was not always freely available, as well as data volume and processing capabilities, which favoured governmental scientists. Active radar data on some levels fulfilled the geomorphic requirements such as retrieval of form, texture as well as height. Unfortunately processing of such image data required significant technical capabilities and was not easy to interpret, given numerous variables associated with the backscatter of the microwave signal. Early earth observation missions were deployed at a time when the full extent of global change, driven by anthropogenic activity had not been fully comprehended. However, older legacy data is now of profound value, since it provides a comparative baseline against which change can be quantified. The study period also saw the gradual transfer of military GPS capabilities to the civilian sector, which facilitated field activities and geometric correction of imagery.