Global Ultraviolet Imager (GUVI)
Fact Sheet (PDF) (Requires Adobe Acrobat Reader )
Instrument Web Site Aerospace GUVI GUVI is designed to observe the glow of the Earth's upper atmosphere in ultraviolet light so scientists can better understand the properties of this atmospheric region. The upper atmosphere is known to respond to both external influences, such as solar variations, and internal motions originating in the atmosphere near the Earth's surface. GUVI is being used to determine energy inputs from the sun into a region of the upper atmosphere where ultraviolet light ionizes the atoms and molecules. This area of Earth's atmosphere is home to the aurora and electrical currents that heat the upper atmosphere during magnetic storms. It's where radio waves are reflected back to Earth making long-distance radio communication possible. GUVI, a spatial-scanning far-ultraviolet spectrograph, is globally measuring the composition and temperature profiles of the MLTI region, as well as its auroral energy inputs. GUVI is looking at sources of far-ultraviolet light originating in the Earth's upper atmosphere, such as the aurora, and is counting individual particles of light, or photons, emitted by the atmosphere. GUVI is the first instrument sensitive enough to look, in detail, at composition changes in the upper atmosphere. GUVI is globally scanning the MLTI region looking for aurora and other sources of ultraviolet light every 1.5 hours – the time it takes to complete an orbit cycle. During each orbit cycle, GUVI is acquiring day, night, and auroral observations. Its very sophisticated, sensitive optical devices are enabling scientists to see extremely minute amounts of light from space, for the first time, and create images of the upper atmosphere's composition changes.
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