Article (Scientific journals)
SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere
Bertaux, Jean-Loup; Nevejans, D.; Korablev, O. et al.
2007In Planetary and Space Science, 55, p. 1673-1700
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Keywords :
Venus; airglow; ozone; spectroscopy; ultraviolet; SPICAV
Abstract :
[en] Spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAV) is a suite of three spectrometers in the UV and IR range with a total mass of 13.9 kg flying on the Venus Express (VEX) orbiter, dedicated to the study of the atmosphere of Venus from ground level to the outermost hydrogen corona at more than 40,000 km. It is derived from the SPICAM instrument already flying on board Mars Express (MEX) with great success, with the addition of a new IR high-resolution spectrometer, solar occultation IR (SOIR), working in the solar occultation mode. The instrument consists of three spectrometers and a simple data processing unit providing the interface of these channels with the spacecraft. A UV spectrometer (118-320 nm, resolution 1. 5 nm) is identical to the MEX version. It is dedicated to nadir viewing, limb viewing and vertical profiling by stellar and solar occultation. In nadir orientation, SPICAV UV will analyse the albedo spectrum (solar light scattered back from the clouds) to retrieve SO2, and the distribution of the UV-blue absorber (of still unknown origin) on the dayside with implications for cloud structure and atmospheric dynamics. On the nightside, 7 and 6 bands of NO will be studied, as well as emissions produced by electron precipitations. In the stellar occultation mode the UV sensor will measure the vertical profiles of CO2, temperature, SO2, SO, clouds and aerosols. The density/temperature profiles obtained with SPlCAV will constrain and aid in the development of dynamical atmospheric models, from cloud top (similar to 60 km) to 160 km in the atmosphere. This is essential for future missions that would rely on aerocapture and acrobraking. UV observations of the upper atmosphere will allow studies of the ionosphere through the emissions of CO, CO+, and CO2+, and its direct interaction with the solar wind. It will study the H corona, with its two different scale heights, and it will allow a better understanding of escape mechanisms and estimates of their magnitude, crucial for insight into the long-term evolution of the atmosphere. The SPICAV VIS-IR sensor (0.7-1.7 mu m, resolution 0.5-1.2 nm) employs a pioneering technology: an acousto-optical tunable filter (AOTF). On the nightside, it will study the thermal emission peeping through the clouds, complementing the observations of both VIRTIS and Planetary Fourier Spectrometer (PFS) on VEX. In solar occultation mode this channel will study the vertical structure of H2O, CO2, and aerosols. The SOIR spectrometer is a new solar occultation IR spectrometer in the range lambda=2.2-4.3 mu m, with a spectral resolution lambda/Delta lambda > 15,000, the highest on board VEX. This new concept includes a combination of an echelle grating and an AOTF crystal to sort out one order at a time. The main objective is to measure HDO and H2O in solar occultation, in order to characterize the escape of D atoms from the upper atmosphere and give more insight about the evolution of water on Venus. It will also study isotopes of CO2 and minor species, and provides a sensitive search for new species in the upper atmosphere of Venus. It will attempt to measure also the nightside emission, which would allow a sensitive measurement of HDO in the lower atmosphere, to be compared to the ratio in the upper atmosphere, and possibly discover new minor atmospheric constituents. (C) 2007 Elsevier Ltd. All rights reserved.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Bertaux, Jean-Loup
Nevejans, D.
Korablev, O.
Villard, E.
Quémerais, E.
Neefs, E.
Montmessin, F.
Leblanc, F.
Dubois, J. P.
Dimarellis, E.
Hauchecorne, A.
Lefèvre
Rannou
Chaufray
Cabane
Cernogora
Souchon
Semelin
Reberac
Van Ransbeek
Berkenbosch
Clairquin
Muller
Forget
Hourdin
Talagrand
Rodin
Fedorova
Stepanov
Vinogradov
Kiselev
Kalinnikov
Durry
Sandel
Stern
Gérard, Jean-Claude  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
More authors (26 more) Less
Language :
English
Title :
SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere
Publication date :
2007
Journal title :
Planetary and Space Science
ISSN :
0032-0633
Publisher :
Elsevier, Netherlands
Volume :
55
Pages :
1673-1700
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
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