Global ultraviolet imager (GUVI): measuring composition and energy inputs for the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission

Abstract
<p>The Global Ultraviolet Imager (GUVI) on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission will determine the variability in thermospheric composition, and its response to auroral inputs as well as measuring those inputs. GUVI is the result of twenty years of work in designing large field of regard far ultraviolet (110 - 180 nm) imagers for spaceflight. These systems are based on the concept of a horizon-to-horizon \textquoterightmonochromatic\textquoteright imager. The field of view of a spectrograph is swept from horizon to horizon using a scan mirror. The spectrograph uses a grating to spectrally disperse the light. A two-dimensional detector is used to record spatial and spectral information simultaneously. Images are obtained at discrete wavelengths without the use of filters; this reduces if not eliminates much of the concern about instrumental bandpasses, out-of-band rejection, and characterization of filter responses. Onboard processing is used to bin the spectral information into \textquoterightcolors\textquoteright thereby reducing the overall data rate required. The spectral bandpass is chosen to lie in the far ultraviolet so that the sunlit and dark aurora can be imaged. We review the instrument\textquoterights as delivered performance and the TIMED science requirements. TIMED will be launched May 18, 2000 and will inaugurate the Solar-Terrestrial Connections program at NASA.</p>
Year of Publication
1999
Publisher
Proc. SPIE Vol. 3756, p. 265-276, Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research III, Allen M. Larar