UVIS
UVIS
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Saturn's A Ring From the Inside Out
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The Ultraviolet Imaging Spectrograph (UVIS) is a box of four telescopes that can see ultraviolet light. Ultraviolet (UV) light, known as the cause of sunburn on Earth, is invisible to the human eye.
The instrument measures the views in ultraviolet light, and scientists use these measurements to produce pictures we can see. Since there is no table that maps ultraviolet "colors" to the colors humans see, the team exercises creative freedom when it makes representative images from the collected data.
"It is cool that we can pick our own colors in the pictures we produce," says Dr. Larry W. Esposito, a professor of Astrophysical and Planetary Sciences at the University of Colorado and UVIS Principal Investigator. "No person has ever seen ultraviolet light, although some butterflies can. Our pictures may thus represent a 'butterfly's-eye view' of the Saturn system."
The instrument's unique capabilities expand on the quality of the data collected by Cassini as it orbits the ringed planet.
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Clumps in the A Ring
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Ultraviolet is particularly interesting because it includes the light characteristics of some key chemical elements and compounds. These light patterns are like fingerprints in UVIS observations. They allow scientists to identify conclusively what distant objects are made of.
"Already, UVIS has detected hydrogen, oxygen, methane, water, acetylene and ethane," Esposito says. "Our measurements tell us about the environment of Saturn that surrounds its moons and rings. We have also learned about the composition of Titan's upper atmosphere."
A special technique is used to investigate planets, moons and rings -- looking past them at a distant star or the Sun. How the object blocks out the starlight gives details about its structure. In this way, UVIS is able to map features in Saturn's rings 10 times smaller than those visible to the Cassini cameras.
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Dr. Larry W. Esposito
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In January 2006, UVIS will watch the Sun setting behind Titan, allowing scientists to measure the composition, temperature and structure of Titan's atmosphere.
"We will look for clouds and smoggy haze layers. The Cassini project managers have used our results in the past to estimate the safety of landing on Titan; our new results will indicate how closely the Cassini spacecraft can safely approach Titan."
True to the international flavor of the Cassini mission, the UVIS team includes scientists and engineers from the United States, France, Belgium, Germany and Japan.
This translates to a linguistically engaging environment, Esposito says.
"We get to practice foreign languages at UVIS team meetings!"
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