Voyager’s Infrared Spectrometer (IRIS) acts as three separate instruments. First, it is a very sophisticated thermometer. It can determine the distribution of heat energy a body is emitting, allowing scientists to determine the temperature of that body or substance. Second, the IRIS is a device that can determine when certain types of elements or compounds are present in an atmosphere or on a surface. Third, it uses a separate radiometer to measure the total amount of sunlight reflected by a body at ultraviolet, visible, and infrared frequencies.
The Voyager IRIS instrument obtained one thermal spectrum every 48 seconds (or “FDS count”) throughout each planetary flyby. The instrument was devoted primarily to atmospheric observations, but it did acquire numerous thermal spectra of Saturn’s ring system.
The tabs associated with this page describe the IRIS data files and how to obtain them.