Capability Development of Ultraviolet Analysis and Modeling
in the Saturnian System, 15-R9638

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Principal Investigators
Andrew J. Steffl

G. Randall Gladstone
Kurt D. Retherford

Inclusive Dates:  07/01/06 – Current

Background - The Ultraviolet Imaging Spectrograph (UVIS) on NASA's Cassini spacecraft has returned a wealth of scientific observations of the Saturn system. After a one-year proprietary period, these data are released to the public. Although UVIS is a highly capable instrument, one of its two spectrographic channels, the Extreme Ultraviolet (EUV) channel, suffers from a light leak that renders analysis of this data difficult. The Cassini Data Analysis Program and other programs through NASA fund researchers to work with such data. This project team intends to capitalize on these programs, but first must successfully demonstrate that the effects of the EUV channel light leak can be mitigated and that the team has sufficient experience analyzing data from the Saturnian system.

Approach - Three pilot projects in three separate areas of research have been identified that will demonstrate SwRI's ability to analyze UVIS data and result in new research findings that will establish a track record of Saturn ultraviolet science at SwRI. These three pilot projects are analyzing the magnetospheric emissions of Saturn, as observed during the Cassini spacecraft's approach to Saturn; searching for emissions from material from the plume of Saturn's moon, Enceladus; and mapping the far ultraviolet reflectance of Saturn's moons Enceladus and Iapetus.

Accomplishments - SwRI developed software to produce information about the geometry of the UVIS observations, such as the position and velocity of the Cassini spacecraft relative to Saturn and the location of the UVIS field of view, relative to various celestial bodies. In addition, SwRI developed techniques to successfully remove the increased background level caused by the EUV channel light leak. This is an important accomplishment as it demonstrates SwRIís ability to analyze EUV channel data.

Data from the Extreme Ultraviolet (EUV) channel of the Cassini Ultraviolet Imaging Spectrometer (UVIS). The top panel shows the pattern of elevated background counts due a light leak in the instrument. The bottom panel shows the same data after background removal techniques have been applied. Spectra of the Saturnian aurora (middle of the image) and a hot star (lower one-third of the image) are present in the data.

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