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Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV)

NSSDCA ID: 2005-045A-03

Mission Name: Venus Express
Principal Investigator:Dr. Jean-Loup C. Bertaux

Description

The Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus (SPICAV) instrument is an imaging spectrometer operating in the ultraviolet and infrared range. It is designed primarily to study the atmosphere of Venus, specifically it will study atmospheric composition and structure, water vapor abundance, the variability of sulfur dioxide and the unknown UV absorber, the vertical structure of the atmosphere, including HDO/H2O and aerosols, sulfur compounds and molecular oxygen, and the interaction of the upper atmosphere with the solar wind. It will also be used to study the surface temperature of Venus.

SPICAV comprises three channels, one ultraviolet channel and two infrared channels. The ultraviolet spectrometer channel (SPICAV-UV) is dedicated to nadir viewing, limb viewing, and vertical profiling by stellar and solar occultation. It covers 0.118 to 0.320 microns with a resolution of 0.8 nm and a spectral resolving power (lambda/delta lambda) of about 300. The field of view is 55 x 8.7 radians. A set of optics composed of an entrance slit, mirrors, and a holographic diffraction grating which focuses the radiation onto a 384 x 288 pixel CCD equipped with an image intensifier tube. The pixel size is 23 x 23 microns and the field of view of one pixel is 40 arc seconds.

The near infrared channel, SPICAV-IR, is designed to make nadir measurements of water abundance above the clouds and do vertical profiling during solar occultation. It covers 0.25 to 1.7 microns with a resolution of 0.5 to 1.2 nm, a resolving power of about 1300 and a field of view of 2 degrees (0.2 radians/pixel). Radiation enters through a 12 mm diameter telescope and is directed to an acousto-optical tuneable filter (AOTF) which uses an acoustic wave applied to a tellurium oxide crystal. Two output beams from the AOTF are collimated by another lens and detected by two 2.4 x 2.4 mm hybrid silicon/indium gallium arsenide PIN photodiodes.

The other channel, the solar occultation infrared channel, is designed specifically for solar occultation measurements to give fine details of atmospheric composition above the clouds. It uses a high resolution IR echelle spectrometer covering 2.3 to 4.2 microns with a resolving power of 15000 - 20000. The optical entrance is a newton-type telescope with a focal length of 180 mm, two parabolic mirrors, a zinc selenide lens and a tellurium oxide polarizing prism. The filtered and dispersed light is passed to a photo-voltaic mercury cadmium telluride (HgCdTe) detector with a 320 x 256 array of 30 micron square pixels. the detector is mounted in a dewer cooled by a 0.4 W Stirling cycle rotary microcooler.

SPICAV is based on the SPICAM instrument flown on Mars Express.

Alternate Names

  • SPICAV
  • VenusExpress/SPICAV

Discipline

  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Jean-Loup C. BertauxPrincipal InvestigatorCentre National de la Recherche Scientifiquebertaux@aerov.jussieu.fr
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