Ultraviolet Spectrometer (UVS)

Description

The UV spectrometer was designed to measure atmospheric properties, and to measure radiation in the wavelength range from O.O4 to 0.16 micrometers (400 to 1600 A). Two modes of instrument operation were planned, airglow and occultation. In the airglow mode the atmospheric radiation was measured. This radiation is predominantly resonance-scattered solar radiation, where the scattering is by molecular or atomic atmospheric constituents such as hydrogen (1216 A) or helium (584 A). In the occultation mode, sunlight was reflected into the spectrometer, and the solar spectrum was recorded. As the atmosphere moved between the spacecraft and the sun, the absorption characteristics of the atmosphere were obtained over the measured wavelength region. The absorption spectrum was used to identify the absorber as well as to measure its abundance in the line of sight to the sun. In addition, the atmospheric thermal structure could be inferred.