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ESA Cosmic Vision 2015-2025 –
The Venus Entry Probe Initiative (VEP)
E. Chassefière (France), K. Aplin (U.K.), C. Ferencz (Hungary), T. Imamura (Japan),
O. Korablev (Russia), J. Leitner (Austria), J. Lopez-Moreno (Spain), B. Marty (France),
D. Titov (Germany), C. Wilson (U.K.), O. Witasse (NL).
presented by J. Leitner, Dept. of Astronomy, Univ. of Vienna, Austria
1st VEP Landing-Sites Workshop, November 14-15, 2006, Vienna, Austria
ESA Cosmic Vision
2015-2025
framework program
Scientific questions in the framework program
1. What are the conditions for life and planetary formation?
1.1 From gas and dust to stars and planets
Map the birth of stars and planets by peering into the highly obscured cocoons
where they form.
1.2 From exo-planets to bio-markers
Search for planets around stars other than the Sun, looking for bio-markers
in their atmospheres, and image them.
1.3 Life and habitability in the Solar System
Explore in-situ the surface and subsurface of the solid bodies in the Solar
System most likely to host – or have hosted – life.
Explore the environmental conditions that makes life possible.
Scientific questions in the framework program
2. How does the Solar System work?
2.1 From the Sun to the edge of the Solar System
Study the plasma and magnetic field environment around the Earth and around
Jupiter, over the Sun’s poles, and out to the heliosphere where the solar wind
meets the interstellar medium.
2.2 The giant planets and their environments
In-situ studies of Jupiter, its atmosphere and internal structure.
2.3 Asteroids and other small bodies
Obtain direct laboratory information by analyzing samples from a
Near-Earth Object.
Scientific questions in the framework program
3. What are the fundamental laws of the Universe?
3.1 Explore the limits of contemporary physics
Use space stable and gravity-free environment to search for tiny deviations
from the standard model of fundamental interactions.
3.2 The gravitational wave Universe
Detect and study the gravitational radiation background generated at
the Big Bang.
3.3 Matter under extreme conditions
Probe gravity theory in the very strong environment of black holes and
other compact objects, and the state of matter at supra-nuclear energies
in neutron stars.
Scientific questions in the framework program
4. How did the Universe originate and what is it made of?
4.1 The early Universe
Define the physical processes that led to the inflationary phase in the early
Universe, during which a drastic expansion supposedly took place.
Investigate the nature and origin of the Dark Energy that is accelerating
the expansion of the Universe.
4.2 The Universe taking shape
Find the very first gravitationally bound structures that were assembled in
the Universe – precursors to today’s galaxies, groups and clusters of galaxies –
and trace their evolution to the current epoch.
4.3 The evolving violent Universe
Trace the formation and evolution of the super-massive black holes at galaxy
centers – in relation to galaxy and star-formation – and trace the life cycles
of matter in the Universe along its history.
ESA Cosmic Vision – Letter of Intent
 Call for M(edium) missions (300 M€), to be launched at the end of 2017
and L(arge) missions (650 M€), to be launched after 2020
 Letter of intent due to March 2007
 Final proposals due to the end of June 2007
 Selection of 3 M missions and 3 L missions in October 2007 for
phases zero studies by ESA and the space industry
ESA SPC have not finally endorsed the call at the last meeting in
November, 7-8  again a delay of some months could result…
(missions selection not before 2008)?
At the EUROPLANET conference in Berlin (September 2006) more
than 10 missions fitting scientific questions 1 and 2 (solar-system
related science) were presented (about 150 themes in general) .
ESA Cosmic Vision – Mission proposal
About 40 pages covering the topics:
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Science objectives
Payload
Mission scenario
Spacecraft description
Operations and archiving
Ground segment
Critical technologies
Schedule and costs
Education and public outreach
How a Venus mission fits
ESA Cosmic Vision
Why is Venus Exploration a key link of Cosmic Vision (CV)?
2 of the 4 scientific questions of the CV program will be directly addressed
through a detailed understanding of the atmosphere-surface-interior coupled
system of Venus and its past evolution:
 1. What are the conditions for life and planetary formation?
1.2 From Exo-planets to bio-markers
How can the detailed knowledge of the atmosphere of Venus,
compared to that of the two other terrestrial planets one, help in
understanding future observations of Earth-like extra-solar planet
atmospheres and the search for habitability, and possibly life,
signatures?
Addressed main questions in this theme:
• Is the present bulk atmosphere of Venus in
thermo-dynamical equilibrium with the surface
and, if not, what are the processes responsible
for a thermo-dynamical disequilibrium?
• Earth-size extra-solar planets can develop a
massive abiotic oxygen atmosphere by means of
a runaway greenhouse and escape of hydrogen
to space?
• What does the atmospheric dynamics and
climate of a slowly rotating Earth-type extra-solar
planet, phase-locked to its central star, looks
like?
Why is Venus Exploration a key link of Cosmic Vision (CV)?
2 of the 4 scientific questions of the CV program will be directly addressed
through a detailed understanding of the atmosphere-surface-interior coupled
system of Venus and its past evolution:
 1. What are the conditions for life and planetary formation?
1.3 Life and habitability in the Solar System
Did Venus, which is the most Earth-like planet of the SolarSystem, offer suitable atmospheric and geological conditions for
life to emerge at some time in the past?
Why did it evolve differently from Earth, and will Earth evolve
toward a Venus-like state in the future?
Addressed main questions in this theme:
• Was Venus originally endowed with as much
water as Earth and, if so, where did the water go?
• Did the massive greenhouse atmosphere have
an impact on the geological history of the planet,
and therefore its potential to host life, e.g. by
modifying the way volatile species are cycled
through the mantle, or by changing upper
boundary thermal conditions?
• What is the impact of cloud coverage on
atmospheric greenhouse and climate, and did
clouds play a significant role in the climatic
evolution of terrestrial planets?
Addressed main questions in this theme:
• Was Venus suitable to the appearance of life at
some time in the past and, if so, when and how
did conditions become unfavourable for life?
• How are volatile species cycled through the
complex mantle-crust-surface-atmosphere-cloud
system, and to which extent do global scale
chemical cycles control bulk atmosphere
composition?
• Will Earth evolve toward a massive Venus-type
greenhouse by future increasing solar radiation
conditions and anthropogenic influence?
• How does a dry, one-plate planet of Earth-size
drive and lose heat from inner layers to its outer
environment?
Why is Venus Exploration a key link of Cosmic Vision (CV)?
2 of the 4 scientific questions of the CV program will be directly addressed
through a detailed understanding of the atmosphere-surface-interior coupled
system of Venus and its past evolution:
 2. How does the Solar System work?
2.1 From the Sun to the edge of the Solar System
How does the Sun interact with Venus’ atmosphere, through its
radiation and particle emissions and what has been the influence
of the Sun and of its evolution on the climate history of Venus?
Addressed main questions in this theme:
• How does an Earth-sized planet without global
magnetic field interact with the solar wind and
why and at which rate does it lose its
atmosphere?
• Does Venus’ atmosphere, ionosphere and solar
wind
interaction
region
present
an
electromagnetic wave activity, due to various
possible phenomena: seismic and/or volcanic
activity, atmospheric lighting, solar wind
interaction?
• Will/Did solar evolution (radiation/particle) play an
important role in driving terrestrial planetary
climate evolution, e.g. powering runaway
greenhouse on Venus or massive escape on
Mars, and determining the presence or absence
of water at their surface?
Scientific Objectives
Questions that should remain unanswered after
VEX and Planet-C:
1) The isotopic composition, especially that of noble gases,
which provides information on the origin and evolution of Venus
and its atmosphere.
2) The chemical composition below the clouds and all the
way down to the surface with more detail than is possible
using remote sensing, in order to fully characterize the
chemical cycles involving clouds, surface and atmospheric
gases.
3) The surface composition and mineralogy at several
locations representing the main types of Venus landforms and
elevations.
4) A search for seismic activity and seismology on the surface,
and measurements at multiple locations to sound the interiors.
Questions that should remain unanswered after
VEX and Planet-C:
5) In situ investigation of the atmospheric dynamics, for instance
by tracking the drift of floating balloons.
6) The composition and microphysics of the cloud layer at
different altitudes and locations, by direct sampling.
7) Solar wind-atmosphere interaction processes and
resulting escape as a function of solar activity.
8) The determination of the surface heat flow of different
landforms and structure-elements.
9) The electromagnetic activity monitoring and mapping of the
planet.
To solve the mysteries of Venus –
a step-by-step approach:
 Step 1 (2005-2015): ESA Venus-Express mission and Japanese
Venus Climate Orbiter mission: focuses on atmospheric and cloud
dynamics, (incomplete) global scale chemistry of the low
atmosphere.
 Step 2 (2015-2025): VEP, an in situ mission, with the use of
balloons, descent probes, microprobes, an orbiter and an
atmosphere sample return unit (in option).
 Step 3 (2025-2035): Long-living landers for the characterisation
of the interior structure and its dynamics on Venus.
Main scientific objectives of the VEP mission
(after the VEP Mission Team meeting in Paris):
Origin, evolution and escape
Ranking
Noble gases abundance and isotope ratio
High
Non noble gas isotope ratios (O, S, etc.)
High
Escape of superthermal neutrals
Medium
Vertical profiles of isotopes of H, O, Ar, Ne above 100 km
Medium
Composition and chemistry
Ranking
Abundance of trace gases not measured by VEX and VCO
High
Vertical profile of trace gases
High
Clouds
Ranking
Composition of cloud particles
High
Optical properties of the clouds
Medium
Main scientific objectives of the VEP mission
(after the VEP Mission Team meeting in Paris):
Dynamics, structure and radiation balance
Ranking
Wind field below and within the clouds
High/Med.
Eddy activity
High
Static stability
High
Radiative balance
Medium
Plasma and wave processes
Ranking
Electromagnetic waves in the ionosphere
High
Electromagnetic activity in atmosphere/lighting
High
Surface and interior
Ranking
Composition and mineralogy of the surface
High
Structure and substructure and interior
Low
Surface morphology (imaging)
High
Surface-atmosphere interactions
High
Planetary heat balance
Low
Mission elements
Planetary orbiter:
 First studied in the VEP study of ESA’s SCI-A
 Possible use of aerobraking to save mass and optimize orbit
 Main tasks: carries role, data collection and relay station
• DP’s, HP, VISP separation
• payload definition in review
• orbital restrictions for DP’S in review
Alternative or additionally: fly-by platform:
 Limited time for measurements of the Venusian
environment
 A good option to realize the atmospheric sample
return experiment
 Limited payload  limited science
 Cheaper!!!
Plasma orbiter:
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Venus Ionospheric Science Probe (VISP)
PI: Royal Institute of Technology (Stockholm, Sweden)
Sub-satellite
Low periapsis, high apoapsis
Science payload ≈ 9 kg: waves, thermal plasma, electron
spectrometer, ion spectrometer, ENA (Energetic Neutral
Atoms) spectrometer, etc.
 Total mass: 50-60 kg
Cloud-altitude balloon:
 VEP study of ESA’s
SCI-A
 Super-pressurized
balloon 3.6 m
diameter
 Deployed at 55-65
km
 5 kg instruments + 3
kg microprobes (15
microprobes for
dynamics
monitoring)
Microprobes for cloud-altitude balloons:
 Studied at the
Oxford University
(United Kingdom)
 100 g each
 Radio-link with
balloon for Doppler
wind measurements
 Measurements of p,
T, v, Vis, IR down to
≈ 10 km altitude
 Imaging system
under review
Low-altitude balloon:
 Preliminary design of a 10 km altitude balloon
for the Lavoisier project (Chassefière et al., 2000)
 Ongoing studies for a 35-km altitude balloon at ISAS/JAXA
• Water vapor pressurized balloon deployed at 35 km
altitude (auto-inflation in the 45-35 km altitude range)
• Solar cells, power ≈ a few watts, has a lifetime of 2
weeks
• Scientific payload of 1 kg (pressure, temperature, other
sensors, TBD), and an emitter allowing Doppler tracking
from Earth (wind determination)
• Entry vehicle sized on the basis of the Hayabusa reentry capsule
• Total mass of the entry vehicle: 35 kg
Descent probes:
 Recent study by M. Van den Berg (Sept. 2006)
 Heritage of the Huygens probe is limited (different entry and
environmental conditions)
 No operational lifetime assumed after landing (now under
review!!!)
 Scaling on Vega, PV, Jupiter Entry Probe study (NASA)
The first one ~ 100 M€, others ~ 20 M€.
Atmospheric sample
return unit:
 Several existing concepts: direct sampling through a pipe
(CNES), use of aerogel (SCIM project), both during a very low
altitude pass (≈50 km on Mars)
 Alternative concept proposed in answer to the Call for Ideas for
the Re-use of the Mars Express Platform (2001)
• Gas collected by cryotrapping during a flyby at ≈130 km
altitude
• Doesn’t require fly-by at low altitude, in extreme thermal
conditions
 Total mass (cryocooler+collector+return capsule) < 50 kg
 Possibility to use the return capsule developed for Hayabusa
(ISAS/ JAXA)
Launching options:
 Future low cost M5 launcher (Japan): 150 kg in
Venus transfer orbit (VTO)
 Soyuz-Fregat (SF-21b from Kourou): 1450 kg in VTO
 HIIA (Japan) : 1500-2000 kg in VTO
 Ariane V: 3000 kg in VTO
 Other (small) launchers (Russia): TBD
Mission scenario
(preliminary)
Preliminary mission scenario(s):
 Core scenaro:
• 4 small/medium descent probes (DP) (3 dayside and
1 nightside)
• 1 cloud-altitude balloon (HB) + 20 microprobes
• 1 low-altitude balloon (LB), floating at 35 km (JAXA concept)
• 1 orbiter for science and data relay
• Atmospheric sample return (ASR) system (provided if it
is feasible)
 Fitting a 650 M€ mission
 different mission elements, orbit options and launch options
are in review
Preliminary mission scenarios(s):
 From a scientific point of view, the scientific value of the HB with the
microprobes is equivalent to the scientific vale of a well-instrument
descent probe.
 Microprobes more focusing on atmospheric dynamics, descent
probes more on chemistry.
 If a LB is added to the HB, the scientific value of the balloon
components slightly exceeds the value of one descent probe, but
clearly a set of descent probes (four) has the best scientific rank.
 Having balloons providing continuous geographical coverage (and
operating several weeks), in complement to the probes is judged
of high scientific interest.
Preliminary mission scenarios(s):
Scenario 1: Launch with a single Soyuz: three options:
- Science orbiter + LB + 4 DP‘s and/or HB: probes are released by
the orbiter before and/or after orbit insertion (one or two before, the
other ones after. No ASR.
- High apoapsis elliptical orbiter + LP + 4 DP‘s and/or HB + ASR:
limited science payload for the orbiter, probes are released sequentially
after orbit insertion. Orbiter is de-orbited and returns atmospheric
samples (collected during orbital phase (possibility to collect several
samples at different altitudes/latitudes/local times.
- Fly-by-platform + LB + 4 DP‘s + ASR: no orbiter, no HB.
Preliminary mission scenarios(s):
Scenario 2: 2 separate launchers with 2 Soyuz:
- Science orbiter launched first (possibly with HB)
Fly-by-platform + LB + DP’s + HB + ASR launched 19 months later.
Scenario 3: 1 Ariane or Proton launch: two options:
- High apoapsis elliptical orbiter + LB + 4 DP‘s and/or HB + ASR:
similar to scenario 1.
- High apoapsis elliptical orbiter + LB + 4 DP‘s + ASR: de-orbited
for atmospheric sample return.
International
cooperation
International cooperation:
 Scientific instruments (and sub-systems) proposed by USA,
Japan, Russia and Europe
 Cooperation with Japan at mission element level under study
(low-altitude balloon, thermal shield for descent probes,
atmosphere return capsule, launcher…)
 Possible cooperation with Russia at mission element level to be
studied (coordination with Venera D, launcher…)
 Possible cooperation with US at mission element level to be
studied
 Support by CNES for preparing the proposal (space mechanics,
mission analysis…)
VEP working-groups:
 Definition of the payload of the descent probes,
Chair: Olivier Witasse (NL)
 Definition of the payload of the balloon probes,
Chair: Colin Wilson (UK)
 Definition of the orbiter payload,
Chair: Csaba Ferencz (H)
 Option of an atmospheric sample return unit,
Chair Benard Marty (FR)
 Definition of possible mission scenarios,
Chair: Eric Chassefiere (FR)
 Selection of potential landing-sites for the descent probes,
Chair: Johannes Leitner (AUT)
Next General VEP
Mission Team Meeting
4th General VEP Mission Team Meeting:
Oxford, UK, January 24-25, 2007
Agenda and further information: http://www.aero.jussieu.fr/VEP/
In cooperation with the space industry
Some topics:
 white paper
 mission scenario
 payload
 international cooperation
 working group reports
 new science objectives?
 preparation of the mission proposal
 etc.