An Infrared interferometer spectrometer and radiometer (IRIS) is a device built into the
Voyager space probe
A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or ...
which enables the measurement of three distinct properties. The instrument itself consists of two separate instruments that together share a single large-aperture telescope system.
The Infrared interferometer spectrometer holds two functions as it can act as a
thermometer
A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer ...
and/or
spectrometer
A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
. The thermometer allows for the observance and measurement of heat energy emitting from an object, and the spectrometer enables the identification of various elements, molecules, and compounds which may be present in an atmosphere and/or on the surface of a body. The separate
radiometer allows for the measurement of reflected infrared, visible, and ultraviolet light off of a body.
History
Early versions of the IRIS were flown on the 1960s Nimbus 3 and Nimbus 4.
In 1971, an early prototype was used on
Mariner 9 to examine Mars.
[
]
Objectives
The device was included, primarily, to meet the following objectives.
* Determination of atmospheric vertical thermal structure (which in turn aids modeling of atmospheric dynamics).[
*Measurement of the abundances of ]hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
and helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
(as a check on theories regarding their ratio in the primitive solar nebula).
*Determination of the balance of energy radiated to that absorbed from the sun (to help investigate planetary origin, evolution, and internal processes).
Discoveries
During the Voyager trip past Saturn, the IRIS discovered complex organic molecules in Titan's atmosphere.
References
*
{{Satellite and spacecraft instruments
Spacecraft instruments