Abstract

The AIRS instrument, scheduled for launch in 1997, is designed to provide new and more accurate data about the atmosphere, land, and oceans for application to climate studies and weather prediction. Loral Infrared and Imaging Systems, Inc. (LIRIS) is currently under contract to the Jet Propulsion Laboratory (JPL) for the concept definition of the AIRS instrument. To meet the National Weather Service's temperature measurement goal, the next generation infrared sounder must have a spectral resolving power of 1200 over the spectral range 3.4–15.4 µm.¹ AIRS employs two multiple-aperture echelle-array spectrometers, each using several grating orders to obtain the desired spectral resolution. Spectral-order separation is accomplished by subdividing the telescope entrance pupil into several apertures, each with its own out-of-band rejection filter. The radiation passing through these apertures is dispersed by the echelle grating before the apertures are reimaged onto a series 2 × n arrays. The focal plane arrays are made of photovoltaic and photoconductive mercury cadmium telluride. To maximize performance all spectrometer components are cooled to 155 K, and the arrays are cooled to 60 K. Systems modeling at LIRIS and JPL indicates that the instrument will achieve the 0.2 K noise-equivalent-delta-temperature goal over most of the spectral bandpass. AIRS will provide global coverage twice per day with a continuous downlink data rate of 1.85 Mbps. The design and development phase of the AIRS program will begin in October 1990.

© 1990 Optical Society of America