'NASA\'s Heat Capacity Mapping Mission (HCMM) project collected Earth data in the visible and thermal bands between April 1978 and September 1980. This was an experimental satellite program which observed day and night thermal conditions of Earth\'s surface. The black and white scenes cover large areas (approximately 500,000 square km at a resolution of 500 meters for the visible channel and 600 meters for the thermal channel. The scale of the imagery is 1:400,000. Areas covered include parts of the United States, western Canada, western Europe, northern Africa, and eastern Australia. The HCMM Digital Source dataset includes approximately 2400 scenes of recovered digital data with a resolution of 100 dpi. The original scenes are 715 km wide and vary in length from 715 to 3,000 km. The file size is 3-13 MB depending on the length of the scene and is stored in a TIFF format. The HCMR transmitted analog data in real time to selected receiving stations. The radiometer was similar to the surface composition mapping radiometer (SCMR) of Nimbus 5 (72-097A). The HCMR had a small instantaneous geometric field of view of 0.83 mrad, high radiometric accuracy, and a wide 716-km swath coverage on the ground so that selected areas were covered within the 12-h period corresponding to the maximum and minimum of temperature observed. The spacecraft was spin stabilized at a rate of 14 rpm. The HCMM circular sun-synchronous orbit allowed the spacecraft to sense surface temperatures near the maximum and minimum of the diurnal cycle. '