Recent breakthroughs in IR detector array and cryocooler technology have made it possible to convert the concepts of optimum, passive, IR sounding to a practical satellite-borne instrument: the Atmospheric Infrared Sounder (AIRS), a grating array IR spectrometer
temperature sounder. AIRS, together with the Advanced Microwave Sounding Unit and the Microwave Humidity Sounder, will form a complementary sounding system for the Earth Observing System to be
launched in the year 2000. The three instruments are expected to become the new operational sounding system for the National Oceanic and Atmospheric Administration.