MODIS - Advanced facility instrument for studies of the earth as a system

The moderate resolution imaging spectrometer (MODIS) is discussed as an earth-viewing sensor that is planned as a facility instrument for the Earth Observing System (EOS) scheduled to begin functioning in the mid-1990s. The MODIS is composed of two mutually supporting sensors that cover a swath width sufficient to provide nearly complete two-day global coverage from a polar-orbiting, sun-synchronous, serviceable platform. High signal-to-noise ratios are to be provided, e.g., 500 to 1 or greater with 10-12-bit quantization over the dynamic ranges of the spectral bands. MODIS' lifetime is expected to be about ten years. One of the MODIS sensors is termed MODIS-N, where N signifies nadir-viewing. The companion to MODIS-N is MODIS-T, where T signifies a tiltable field-of-view. The development of the MODIS facility from conceptual design studies (Phase-A) into detailed design studies (Phase-B) is discussed.