Picture: Etna lava flow, with Catania in the background Low Cost Planetary Missions Conference 2013

Venus Express: a low cost mission

2001: Call for ideas for re-flight of Mars Express spacecraft bus 2002: Selection & approval Nov 2005: launch Apr 2006: Venus Orbit Insertion

Mars Express Venus Express

Astrium, ESA Astrium, ESA

VEx science payload Name Instrument Principal Investigator

ASPERA Analyser of Space Plasma and Energetic Ions

S. Barabash, IRF, .

MAG* Magnetometer T. Zhang, IWF, Graz, Austria.

PFS Planetary Fourier Spectrometer (IR)

V. Formisano, IFSI-CNR, Rome, Italy.

SpicaV/SOIR* UV-IR spectrometer for stellar and solar occultation

J.-L. Bertaux, LATMOS, France.

VERA Venus Radio Science B. Häusler, Uni-BW, Muenchen, Germany.

VIRTIS* UV-Vis-IR Mapping spectrometer

P. Drossard, Obs de Paris, Meudon, France, G. Piccioni, IASF-CNR, Rome, Italy.

VMC* Venus Monitoring Camera

W. Markiewicz, MPS, Germany

Payload is (mostly) recycled from Mars Express and Rosetta missions

Venus Express results The original science objectives for Venus Express were organized in seven

themes Atmospheric Dynamics Atmospheric Structure Atmospheric Chemistry and Processes Clouds and Hazes Energy balance and greenhouse effect Surface, Geology and Surface-Atmosphere interaction Plasma environment and solar wind interaction

Most of the original objectives have been reached and/or superseded.

By now we have well over 300 (peer-reviewed) VEx publications

The following slides present just a few recent highlights...

Atmospheric Dynamics: Winds at different levels

Now VEX reveals dramatic 30% increase in super-rotation rate over 6 years.

Kouyama et al., 2013; Khatuntsev et al., 2013.

Venus Express provided the first ever 3-D determination of winds at different altitudes on Venus.

Hueso et al., 2012

Atmospheric Dynamics – Polar Vortex Polar vortex circulation – a generic feature of planetary atmospheres – is

particularly spectacular and chaotic on Venus (Garate-Lopez et al., 2013)

Limaye et al., 2009 IAPS/INAF

Upper cloud/haze (~70 km) Middle cloud-tops (~60 km)

Upper Atmosphere Dynamics

Evidence of Solar to anti-solar circulation in the upper atmosphere by oxygen glow at and around the anti-solar point from recombination of oxygen atoms.

O, NO, CO2, H non-LTE emissions mapped.

Pag. 7

Upper Atmosphere Dynamics

O2 airglow emission at ~ 97 km – suggest weak or no super-rotation

VIRTIS, SPICAV

Pag. 8

Upper Atmosphere Dynamics

O2 airglow emission at ~ 97 km – suggest weak or no super-rotation

VIRTIS, SPICAV

Pag. 9

NO airglow emission at ~ 115 km suggests super-rotation!

Stiepen et al., in press, 2013 If there is no longer super-rotation at 100 km altitude,

how do its effect persist at 115 km?!?

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Atmospheric structure & convection A mystery: why are more gravity waves observed at high latitudes? Influence of topography?

Atmospheric structure – Radio occultation profiles

150 200 250 300 350 400 450Temperature [K]

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DOY 122 2007 lat: - 7.5°DOY 132 2007 lat: - 46.1°DOY 142 2007 lat: - 77.3°DOY 148 2007 lat: - 87.0°

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Tellmann et al. 2009

low latitudes high latitudes middle latitudes

Tropopause

Atmospheric structure – Radio occultation profiles

Tellmann et al. 2009

Atmospheric structure & convection

Imamura et al., 2013

Atmospheric structure & convection

Convection is suppressed, not enhanced, at subsolar point! Cloud-level convection is enhanced at high latitudes and at night.

Imamura et al., 2013

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Atmospheric structure & convection At high latitudes, gravity waves from deep atmosphere can filter through to mesosphere where they are detected by radio scence.

Atmospheric chemistry – Solar and stellar occultation

Atmospheric chemistry – Summary of VEx preliminary measurements

O3

Tsang et al., 2008

Cottini et al., 2012

Belyaev et al., 2012

Atmospheric chemistry -Mesospheric SO2 changes

Venus Express finds episodic injection of SO2 into mesosphere. • Is this an connected with volcanic activity (like Pinatubo)? • Or is it dynamical variability (like El Niño / La Niña)?

Marcq et al, 2012

Clouds & Hazes

Clouds & Hazes

Cloud-top height measured on the dayside by measuring depth of CO2 absorption line in reflected sunlight (Ignatiev et al., 2007)

No variation at low latitudes; decrease of ~7 km toward poles

Ignatiev et al., 2009

Clouds & Hazes

H2SO4 hazes extend to > 90 km, are very variable. Complex mixed phase chemistry similar to Earth polar stratospheric

cloud chemistry.

Zhang et al, 2010

Wilquet et al, 2012

VIRTIS, Mueller, Smrekar et al.

Idunn Mons

Surface mapping - Thermal emission at 1 µm

VEx has found high emissivity areas interpreted as fresh (unweathered) lava flows around volcanoes.

The search for temperature anomalies continues.

Induced magnetosphere response to changing solar wind

Wei et al., 2012

Induced magnetosphere response to changing solar wind

ASPERA, MAG

Wei et al., 2012

Upper atmosphere density variations VEx atmospheric drag experiment

Large day-to-day density variations found.

ESA

VEx aerobraking phase - 2015 P

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Draft orbit control plan

VEx propellant will run out in 2015 (TBC). Before end of mission, an aerobraking phase is proposed.

Permits density measurement down to 130 km (below homopause). Only limited science pointings will be supported in this phase.

Conclusions – 10 productive (Venus) years at Venus

First global monitoring of the composition of the lower atmosphere in the near IR transparency “windows”

First application of the solar/stellar occultation technique at Venus

First coherent observations of Venus in the spectral range from UV to thermal infrared

First coherent study of the atmospheric temperature and dynamics at different levels

First study of the middle and upper atmosphere dynamics from O2, O, and NO emissions

First use of 3D ion mass analyzer, high energy resolution electron spectrometer, and energetic neutral atom imager

First measurements of the non-thermal atmospheric escape

First measurements of global surface temperature distribution from orbit

First operational experience of aerobraking for ESA – 2015?

VEx aerobraking phase - 2015

Science during aerobraking: atmospheric densities will be obtained down to 130 kilometres altitude (c.f. 165 km in nominal science operations).

Per

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Draft orbit control plan