An Infrared interferometer spectrometer and radiometer (IRIS) is a device built into the

Voyager Voyager may refer to: Computing and communications * LG Voyager, a mobile phone model manufactured by LG Electronics * NCR Voyager, a computer platform produced by NCR Corporation * Voyager (computer worm), a computer worm affecting Oracle ...

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 thermomete ...

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 th ...

. 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 Mariner 9 (Mariner Mars '71 / Mariner-I) was a robotic spacecraft that contributed greatly to the exploration of Mars and was part of the NASA Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from LC-36B at Cape Canaveral Ai ...

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

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's atmosphere. This discovery would be further examined by the Cassini-Huygens probe in 2005.

References

* {{Satellite and spacecraft instruments Spacecraft instruments