Heat Capacity Mapping Mission (HCMM)

The mission was the first of a series of NASA Applications Explorer Missions and is also known as AEM-A. Day/night coverage over a given area occurred at intervals ranging from 12 to 36 hours with a 16 day repeat cycle.

The satellite was operational from April 1978 to September 1980. The initial orbit of 620 km was lowered to 540 km in February of 1980. Coverage includes parts of the United States, Canada, Europe, Africa, and Australia. The source data was transmitted to seven ground stations and stored on binary magnetic tape. The source data on tape is no longer readable and the only remaining set of HCMM data is on black and white film. Since the data could be of historical value for global change research, the images have been scanned at 1000 dpi (25 micron) making the data accessible to the scientific community. The collection includes approximately 47,000 scenes with a Hotine Oblique Mercator projection.

The Heat Capacity Mapping Mission Radiometer operated with two channels. The first detected visible to near infrared (0.5 – 1.1 micrometers) radiation and the second detected thermal infrared (10.5 – 12.5 micrometers) radiation. HCMM nomenclature refers to the visible to near infrared channel as Vis and the thermal infrared channel as IR. The scenes are designated as Day-Vis, Day-IR or Night-IR.

A HCMM scene has a width of 715 km with a resolution of 500 meters for the visible channel and 600 meters for the thermal channel.