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A new face of Venus from Venus Express/VIRTIS observations
Pierre Drossart, Giuseppe Piccioni and the VIRTIS team


VIRTIS : the imaging spectrometer of Venus Express / heritage from Rosetta (A. Coradini)

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


First motivation for VIRTIS/Venus Express after Galileo Venus Flyby in 1990 : let us go back !

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


The new face of Venus
12 April 2006 Distance 210 000 km

First VIRTIS observation on Venus Express 12 April 2006 Venus Orbit Insertion

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Off- Pericentre observations
#2: Ascending arc #3: Apocentre mosaic

#1: Pericentre nadir

#5: Stellar occultation

#7: Limb

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


5µ m
Wavelength direction


VIRTIS-H line of sight

VIRTIS-M spectrum 2 Monochromatic 2D images of -M

2µm 1µm

1

y x
Parameter VIRTIS-M Visible Spectral Range [µm] Spectral sampling [nm] FOV IFOV Pupil Diameter [mm] F# 5.6 0.27-1.1 1.9 Infrared 1.05-5.19 9.8

Instrumental characteristics
VIRTIS-H

Spatial directions

.250µm

1.88-5.03 0.6 0.58mrad x 1.75mrad per px N/A 32 2.04

64mrad x 64mrad 0.25mrad x 0.25mrad 47.5 3.2

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


1. Venus surface
Night side spectrum and relative surface/atmosphere contribution (from Meadows and Crisp, JGR, 1996)

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Temperature map of the surface of Venus (South pole view) VIRTIS/Venus Express Magellan (radar)

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


3. Night side spectroscopy

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Composition measurements
Equatorial composition · CO : 25 ppm · OCS : 15 ppm +cut-off altitude 30 km · H20 : 30 ppm Variations of CO and OCS with latitude (+/-)
Moscow / 2 October E. Marcq et al, Meudon 2007 / P. Drossart VIRTIS-Venus Express

CO OCS

H2O and HDO


4. Thermal profile retrieval algorithm at 4.3 µm

D. Grassi et al

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


5. Cloud height measurements from CO2 band depth

Titov et al
Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Observations of the South polar vortex by VIRTIS

Observations Ю 5 microns

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


6. CO2 emission 4.3 µm band Peak altitude around 110 km

Spectre jour Fluorescence

Spectre nuit

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


O2 emissions

Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express


Summary of VIRTIS observations
· Data volume at orbit 500 : > 150 Gigabytes · First level analysis : routinely achieved.
­ Measurements of physical quantities (winds, Tsurf, etc.) ­ First papers submitted ­ First data set delivered ESA (Planetary Science Archive)

· Second level objectives : just beginning
­ ­ ­ ­ General circulation : dynamics and composition Radiative balance Survey of potential surface variability (volcanoes) Systematic survey of emissions by CO2 et O2 and modeling

· Next mission to come : Venus Climate Orbiter (JAXA), VESPER (NASA) ? , in situ mission ??
Moscow / 2 October 2007 / P. Drossart VIRTIS-Venus Express