Since the early 1960s, meteorological, hydrological, and oceanographic data from satellites have had a major impact on environmental analysis, weather forecasting, and atmospheric research in the United States and throughout the world. While polar-orbiting satellites provide snapshots of various phenomena once or twice daily, it was not until December 1966, when the National Aeronautics and Space Administration (NASA) launched the first geostationary Applications Technology Satellite, that the ability to see weather systems in animation was realized. NASA research and development fostered the Geostationary Operational Environmental Satellite (GOES) program within the National Oceanic and Atmospheric Administration (NOAA) culminating with NOAA's operation of the GOES series following the launch of GOES-1 in October 1975. The Visible and Infrared Spin Scan Radiometer (VISSR) provided imagery from these original GOES satellites.
GOES significantly advanced the ability to observe weather systems by providing frequent interval visible and infrared imagery of the earth surface, atmospheric moisture, and cloud cover. GOES data soon became a critical part of National Weather Service (NWS) operations by providing unique information about existing and emerging storm systems both day and night. Subsequently, more spectral bands were added to the VISSR, enabling the GOES system to acquire multispectral measurements from which atmospheric temperature and humidity sounding could be derived: the VISSR Atmospheric Sounder (VAS) was introduced on GOES-4 in 1981. Although the addition of more spectral bands represented a major improvement in satellite capability, several compromises were necessary. First, imaging and sounding could not be done at the same time. Second, the spinning GOES-VAS viewed the earth only 5% of the time, so it was not possible to attain the instrument signal-to-noise ratios needed for either high-quality soundings or high spatial resolution image data. Thus, while the image data were used operationally, the sounding data were used only in special experiments. Recognizing the need for both operational imaging and sounding, NOAA began development of its next generation of geostationary satellites, GOES I-M, in 1985.
On 13 April 1994, the first of NOAA's next generation of geostationary satellites, GOES-8, was launched. The GOES-8 spacecraft is designed for a five-year lifetime. It introduces improved capabilities to observe weather-related phenomena on all scales from geostationary altitude and represents the evolution of geostationary satellite technology in the United States during nearly a quarter of a century.
Responding to user requirements for improvements in the GOES-VAS system, the GOES-8 system has (a) no conflict between imaging and sounding operations, (b) multispectral imaging with improved resolution and better signal to noise in the infrared bands, (c) operational atmospheric temperature and moisture soundings, (d) more precise image frame-to-frame registration, and (e) stable longterm calibration.
The earth-oriented GOES-8 enables more efficient data gathering by both the imager and sounder. Sounding and imaging operations are now performed by different and separate instruments. A sounder with higher radiometric sensitivity enables operational temperature and moisture profile retrieval from geostationary altitude for the first time.