Instrument Investigators Description Some Scientific Objectives

Composite Infrared Spectrometer

An optical remote-sensing instrument

Principal Investigator: Virgil Kunde

NASA Goddard Space Flight Center

CIRS is a 50.8 cm aperture Cassegrain telescope equipped with dual interferometers to measure infrared emission from atmospheres, rings, and surfaces. Sensitive to wavelengths of 10 cm-1 to 1400 cm-1 (1 mm to 7Ám), with an apodized spectral resolution as high as 0.5 cm-1. Within Saturn's and Titan's atmospheres, to map the global temperature structure and gas composition, to obtain information on hazes, clouds, and energetic processes, and to search for new molecular species. To map the global temperatures at Titan's surface, and the composition and thermal characteristics of Saturn's rings and icy satellites.

All of Cassini's optical remote-sensing instruments, including CIRS, are rigidly mounted on the on the plus-X side of the spacecraft, with their apertures (seen with red aperture covers in the photograph) directed toward minus-Y. Detector electronics are cooled by passive radiation from dedicated radiator plates that face in the plus-X direction into deep, cold space. Pointing the optical instruments at their targets requires rotating the entire spacecraft.

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