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).

1st VEP Landing-Sites Workshop, November 14-15, 2006, Vienna, Austria

presented by J. Leitner, Dept. of Astronomy, Univ. of Vienna, Austria

ESA Cosmic Vision2015-2025

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 planetsMap the birth of stars and planets by peering into the highly obscured cocoonswhere they form.

1.2 From exo-planets to bio-markersSearch for planets around stars other than the Sun, looking for bio-markersin their atmospheres, and image them.

1.3 Life and habitability in the Solar SystemExplore in-situ the surface and subsurface of the solid bodies in the SolarSystem 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 SystemStudy 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 windmeets the interstellar medium.

2.2 The giant planets and their environmentsIn-situ studies of Jupiter, its atmosphere and internal structure.

2.3 Asteroids and other small bodiesObtain 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 physicsUse space stable and gravity-free environment to search for tiny deviationsfrom the standard model of fundamental interactions.

3.2 The gravitational wave UniverseDetect and study the gravitational radiation background generated at the Big Bang.

3.3 Matter under extreme conditionsProbe gravity theory in the very strong environment of black holes and other compact objects, and the state of matter at supra-nuclear energiesin neutron stars.

Scientific questions in the framework program

4. How did the Universe originate and what is it made of?

4.1 The early UniverseDefine the physical processes that led to the inflationary phase in the earlyUniverse, during which a drastic expansion supposedly took place.Investigate the nature and origin of the Dark Energy that is acceleratingthe expansion of the Universe.

4.2 The Universe taking shapeFind the very first gravitationally bound structures that were assembled inthe Universe – precursors to today’s galaxies, groups and clusters of galaxies – and trace their evolution to the current epoch.

4.3 The evolving violent UniverseTrace the formation and evolution of the super-massive black holes at galaxycenters – 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:

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 Solar-System, 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 afterVEX 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 afterVEX 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 escapeOrigin, evolution and escape RankingRanking

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 chemistryComposition and chemistry RankingRanking

Abundance of trace gases not measured by VEX and VCO High

Vertical profile of trace gases High

CloudsClouds RankingRanking

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 balanceDynamics, structure and radiation balance RankingRanking

Wind field below and within the clouds High/Med.

Eddy activity High

Static stability High

Radiative balance Medium

Plasma and wave processesPlasma and wave processes RankingRanking

Electromagnetic waves in the ionosphere High

Electromagnetic activity in atmosphere/lighting High

Surface and interiorSurface and interior RankingRanking

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:

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 re-entry 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.