Editing Cassini–Huygens (section)

=== Description ===
''Cassini''{{'}}s instrumentation consisted of: a [[synthetic aperture radar]] mapper, a [[charge-coupled device]] imaging system, a visible/[[infrared]] mapping [[spectrometer]], a composite infrared spectrometer, a [[cosmic dust]] analyzer, a radio and [[Plasma (physics)|plasma]] wave experiment, a plasma spectrometer, an [[ultraviolet]] imaging spectrograph, a [[magnetospheric]] imaging instrument, a [[magnetometer]] and an [[ion]]/neutral [[mass spectrometer]]. [[Telemetry]] from the communications [[antenna (electronics)|antenna]] and other special transmitters (an [[S-band]] transmitter and a dual-frequency [[Ka band|K<sub>a</sub>-band]] system) was also used to make observations of the atmospheres of Titan and Saturn and to measure the [[gravity]] fields of the planet and its satellites.

{{glossary}}
{{term|Cassini Plasma Spectrometer (CAPS)}}
{{defn|CAPS was an in situ instrument that measured the flux of charged particles at the location of the spacecraft, as a function of direction and energy. The ion composition was also measured using a [[time-of-flight mass spectrometer]]. CAPS measured particles produced by ionisation of molecules originating from Saturn's and Titan's ionosphere, as well as the plumes of Enceladus. CAPS also investigated [[Plasma (physics)|plasma]] in these areas, along with the [[solar wind]] and its interaction with Saturn's magnetosphere.{{r|cassini.orbiter|cassini.caps}} CAPS was turned off in June 2011, as a precaution due to a "soft" electrical [[short circuit]] that occurred in the instrument. It was powered on again in March 2012, but after 78 days another short circuit forced the instrument to be shut down permanently.<ref name=cassini.march2012/>}}

{{term|[[Cosmic Dust Analyzer]] (CDA)}}
{{defn|The CDA was an in situ instrument that measured the size, speed, and direction of tiny dust grains near Saturn. It could also measure the grains' chemical elements.<ref name=Altobelli_2016/> Some of these particles orbited Saturn, while others came from other star systems. The CDA on the orbiter was designed to learn more about these particles, the materials in other celestial bodies and potentially about the origins of the universe.<ref name=cassini.orbiter/>}}

{{term|Composite Infrared Spectrometer (CIRS)}}
{{defn|The CIRS was a remote sensing instrument that measured the [[infrared radiation]] coming from objects to learn about their temperatures, thermal properties, and compositions. Throughout the ''Cassini–Huygens'' mission, the CIRS measured infrared emissions from atmospheres, rings and surfaces in the vast Saturn system. It mapped the atmosphere of Saturn in three dimensions to determine temperature and pressure profiles with altitude, gas composition, and the distribution of [[aerosols]] and clouds. It also measured thermal characteristics and the composition of satellite surfaces and rings.<ref name=cassini.orbiter/>}}

{{term|Ion and Neutral Mass Spectrometer (INMS)}}
{{defn|The INMS was an in situ instrument that measured the composition of charged particles (protons and heavier ions) and neutral particles (atoms and molecules) near Titan and Saturn to learn more about their atmospheres.  The instrument used a [[quadrupole mass spectrometer]]. INMS was also intended to measure the positive ion and neutral environments of Saturn's icy satellites and rings.{{r|cassini.orbiter|Waite_2004|cassini.inms}} }}

{{term|Imaging Science Subsystem (ISS)}}
{{defn|The ISS was a remote sensing instrument that captured most images in [[visible light]], and also some infrared images and [[ultraviolet]] images. The ISS took hundreds of thousands of images of Saturn, its rings, and its moons. The ISS had both a wide-angle camera (WAC) and a narrow-angle camera (NAC). Each of these cameras used a sensitive [[charge-coupled device]] (CCD) as its [[electromagnetism|electromagnetic wave]] detector. Each CCD had a 1,024x1,024 square array of pixels, each pixel 12&nbsp;[[μm]] square. Both cameras allowed for many data collection modes, including on-chip data compression, and were fitted with spectral filters that rotated on a wheel to view different bands within the electromagnetic spectrum ranging from 0.2 to 1.1&nbsp;μm.{{r|cassini.orbiter|Porco_2004}} }}

{{term|[[Spacecraft magnetometer#Dual technique|Dual Technique Magnetometer]] (MAG)}}
{{defn|The MAG was an in situ instrument that measured the strength and direction of the [[Magnetosphere of Saturn|magnetic field around Saturn]]. The magnetic fields are generated partly by the molten core at Saturn's center. Measuring the magnetic field is one of the ways to probe the core. MAG aimed to develop a three-dimensional model of Saturn's magnetosphere, and determine the magnetic state of Titan and its atmosphere, and the icy satellites and their role in the magnetosphere of Saturn.{{r|cassini.orbiter|Dougherty_2004}}}}

{{term|Magnetospheric Imaging Instrument (MIMI)}}
{{defn|The MIMI was both an in situ and remote sensing instrument that produces images and other data about the particles trapped in Saturn's huge magnetic field, or magnetosphere. The in situ component measured energetic ions and electrons while the remote sensing component (the Ion And Neutral Camera, INCA) was an [[energetic neutral atom]] imager.<ref name=cassini.mimi-inca/> This information was used to study the overall configuration and dynamics of the magnetosphere and its interactions with the solar wind, Saturn's atmosphere, Titan, rings, and icy satellites.{{r|cassini.orbiter|Krimigis_2004}} }}

{{term|Radar}}
{{defn|The on-board radar was an active and passive sensing instrument that produced maps of Titan's surface. Radar waves were powerful enough to penetrate the thick veil of haze surrounding Titan. By measuring the send and return time of the signals it is possible to determine the height of large surface features, such as mountains and canyons. The passive radar listened for radio waves that Saturn or its moons may emit.<ref name=cassini.orbiter/>}}

{{term|Radio and Plasma Wave Science instrument (RPWS)}}
{{defn|The RPWS was an in situ instrument and remote sensing instrument that receives and measures radio signals coming from Saturn, including the radio waves given off by the interaction of the solar wind with Saturn and Titan. RPWS measured the electric and magnetic wave fields in the interplanetary medium and planetary magnetospheres. It also determined the electron density and temperature near Titan and in some regions of Saturn's magnetosphere using either plasma waves at characteristic frequencies (e.g. the [[upper hybrid oscillation|upper hybrid]] line) or a [[Langmuir probe]]. RPWS studied the configuration of Saturn's magnetic field and its relationship to Saturn Kilometric Radiation (SKR), as well as monitoring and mapping Saturn's ionosphere, plasma, and lightning from Saturn's (and possibly Titan's) atmosphere.<ref name=cassini.orbiter/>}}

{{term|[[Radio Science Subsystem]] (RSS)}}
{{defn|The RSS was a remote-sensing instrument that used radio antennas on Earth to observe the way radio signals from the spacecraft changed as they were sent through objects, such as Titan's atmosphere or Saturn's rings, or even behind the [[Sun]]. The RSS also studied the compositions, pressures and temperatures of atmospheres and ionospheres, radial structure and particle size distribution within rings, body and system masses and the [[gravitational field]]. The instrument used the spacecraft X-band communication link as well as S-band downlink and K<sub>a</sub>-band uplink and downlink.<ref name=cassini.orbiter/>

[[File:Cassini_uvis2.jpg|alt=Cassini UVIS|thumb|''Cassini'' UVIS instrument built by the Laboratory for Atmospheric and Space Physics at the University of Colorado.]]}}
{{term|Ultraviolet Imaging Spectrograph (UVIS)}}
{{defn|1=The UVIS was a remote-sensing instrument that captured images of the ultraviolet light reflected off an object, such as the clouds of Saturn and/or its rings, to learn more about their structure and composition. Designed to measure ultraviolet light over wavelengths from 55.8 to 190&nbsp;nm, this instrument was also a tool to help determine the composition, distribution, aerosol particle content and temperatures of their atmospheres. Unlike other types of spectrometer, this sensitive instrument could take both spectral and spatial readings. It was particularly adept at determining the composition of gases. Spatial observations took a wide-by-narrow view, only one [[pixel]] tall and 64 pixels across. The spectral dimension was 1,024 pixels per spatial pixel. It could also take many images that create movies of the ways in which this material is moved around by other forces.<ref name=cassini.orbiter/>{{pb}}

UVIS consisted of four separate detector channels, the Far Ultraviolet (FUV), Extreme Ultraviolet (EUV), High Speed Photometer (HSP) and the Hydrogen-Deuterium Absorption Cell (HDAC).  UVIS collected hyperspectral imagery and discrete spectra of Saturn, its moons and its rings, as well as stellar occultation data.<ref name=Esposito_2004/>{{pb}}

The HSP channel is designed to observe starlight that passes through Saturn's rings (known as stellar occultations) in order to understand the structure and optical depth of the rings.<ref name=Colwell_2010/> Stellar occultation data from both the HSP and FUV channels confirmed the existence of water vapor plumes at the south pole of Enceladus, as well as characterized the composition of the plumes.<ref name=Hansen_2006/>

[[File:PIA18410-TitanSunsetStudies-CassiniSpacecraft-20140527.jpg|thumb|right|VIMS spectra taken while looking through [[Atmosphere of Titan|Titan's atmosphere]] towards the [[Sun]] helped understand the atmospheres of [[exoplanet]]s (artist's concept; May 27, 2014).]]}}

{{term|Visible and Infrared Mapping Spectrometer (VIMS)|Visible and Infrared Mapping Spectrometer (VIMS){{anchor|VIMS}}}}
{{defn|The VIMS was a remote sensing instrument that captured images using visible and infrared light to learn more about the composition of moon surfaces, the rings, and the atmospheres of Saturn and Titan. It consisted of two cameras - one used to measure visible light, the other infrared. VIMS measured reflected and emitted radiation from atmospheres, rings and surfaces over wavelengths from 350 to 5100&nbsp;nm, to help determine their compositions, temperatures and structures. It also observed the sunlight and starlight that passes through the rings to learn more about their structure. Scientists used VIMS for long-term studies of cloud movement and morphology in the Saturn system, to determine Saturn's weather patterns.<ref name=cassini.orbiter/>}}
{{glossary end}}