The United States maintains two civil and one military program to provide meteorological imagery and data from spacecraft in polar and geostationary orbits around the Earth. The civil programs are managed by the National Oceanic and Atmospheric Administration (NOAA) and the military program is managed by the Department of Defense. The National Environmental Satellite, Data, and Information Service (NESDIS) is a unit of NOAA and is responsible for operating the civilian weather satellites (GOES and POES), distributing the satellite data and imagery, archiving the data, and planning for future systems. NESDIS also controls the Department of Defense constellation of polar orbiting weather satellites called Defense Meteorological Satellite Program (DMSP), which is similar to the civilian POES program.
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Due to the classified nature of the DMSP imagery and other data products, the DMSP downlink data is encrypted, and thus the direct readout system is not available to nonmilitary users.
That all comes from this cool-as-hell PDF† about how to build a GOES/POES ground receiving station. Anyways the most obvious target here is probably the DMSP products, rather than, say, a Bruckheimer-esque plot to disrupt NOAA satellite imagery during the height of the Atlantic hurricane season.
† http://noaasis.noaa.gov/NOAASIS/pubs/Users_Guide-Building_Re...