ABSTRACT
Technological developments for military purposes, which continue to be a key driver in Earth observation (EO), and geoinformation science in general, led to the acquisition of the ¤rst satellite-based images in 1960. At the height of the Cold War, the Corona program, declassi¤cation of which ¤nally began in 1995 and only ¤nished in 2002, saw the launch of nearly 150 satellite missions aimed at image capture over areas relevant for the national security of the United States. For DRM purposes Corona as well as sister programs Argon and Lanyard were primarily relevant insofar as they advanced satellite and sensor developments, since the image acquisition was aimed at areas of military relevance, and data were not made available outside the intelligence community. However, following declassi¤cation the data acquired by Corona over its 12-year mission duration have been used for a variety of studies related to DRM. Ÿose range from geological mapping to population growth studies (Dashora et al., 2007), time series analysis of glacier retreat (Narama et al., 2010), volcanic hazard assessment (Karakhanian et al., 2003), or deforestation mapping for landslide hazard assessment (Kerle et al., 2003). Ÿe majority of the images were taken with black and white ¤lm (with a few being taken in color or infrared), with later missions delivering images with spatial resolutions of up to 1.8 m (Galiatsatos et al., 2008). Only three decades later would satellite images of comparable resolution become available for civilian users. Ÿe data had two additional advantages. Ÿe ¤lm strips covered a very narrow (14 km) but also very long (188 km) corridor (Figure 18.3), explaining why o¬en also areas that do not seem to be of much military relevance were imaged. Some of the Corona missions also carried stereo cameras, the data from which, following declassi¤cation, have been used to create digital elevation models (DEMs). Especially prior to the more widespread availability of detailed Light Detection and Ranging
(LiDAR) data or images from modern high resolution stereo satellites, the resulting DEMs with resolutions approximately ranging between 9 m (Schmidt et al., 2001) and 17 m (Galiatsatos et al., 2008) were a valuable data source, for example, to study glacier hazards (Lamsal et al., 2011).
