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EUVS - Extreme Ultraviolet Spectrometer

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EUVS
Extreme Ultraviolet Spectrometer
Dr. A. Ian F. Stewart, Principal Investigator
University of Colorado

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MISSION OBJECTIVES

SUMMARY

The reflective properties of satellite surfaces in the ultraviolet help scientists to determine the composition and physical state of the materials that comprise the surface. One can look for ice and frost or deduce the sizes of grains.

Volcanic eruptions on Io are believed to be the source of the Io torus. Temperatures of the sulfur and oxygen ions in this plasma torus can be more than 10 times the temperatures at the surface of the Sun. These ultraviolet observations will help provide a picture of Io's evolution and its relationship with Jupiter's magnetic field.

The Cassegrain telescope of the UVS has a 250-millimeter aperture and collects light from the observation target. Both the UVS and EUV instruments use a ruled grating to disperse this light for spectral analysis. This light then passes through an exit slit into photomultiplier tubes that produce pulses or "sprays" of electrons. These electron pulses are counted, and these count numbers are the data that are sent to Earth.

The UVS is mounted on the scan platform and can be pointed to an object in inertial space. The EUV is mounted on the spun section of the spacecraft. As Galileo spins, the EUV observes a narrow ribbon of space perpendicular to the spin axis.

The two instruments combined weigh about 9.7 kilograms and use 5.9 watts of power.

EUVS DESCRIPTION

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DESIGN DETAILS

INSTRUMENT PARAMETERS

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