1. OXFORD RAS Venus meeting- 12 November 2010 Colin Wilson Co-P.I. – Univ. of Oxford & Eric Chassefière P.I. – Univ. Paris Sud European Venus Explorer An in-situ Venus explorer to be proposed as a Cosmic Vision M3 mission, for launch in 2020 – 2025

2. OXFORD RAS Venus meeting- 12 November 2010 ESA’s Cosmic Vision Programme ‘Cosmic Vision 2015-2025’ sets out goals for ESA’s Science Programme missions. –What are the conditions for planet formation and the emergence of life? –How does the Solar System work? –What are the fundamental physical laws of the Universe? –How did the Universe originate and what is it made of? Note that this includes Astronomy & Fundamental Physics as well as Solar System missions First selection of missions was in 2007 –2 ‘L-class’ missions: €650m cost cap  EJSM - Europa – Jupiter System Mission  IXO - International X-ray Observatory  LISA - Laser Inferometer to measure gravity waves –2 ‘M-class’ missions: €300m cost cap  Euclid – Dark matter mapper  Plato – Exoplanet finder  Solar Orbiter The current call is for a third M class mission with a nominal launch date by end 2022. –Mission should be able to launch in 2020. €470m cost cap including launch vehicle.

3. OXFORD RAS Venus meeting- 12 November 2010 Why Venus? Venus should be the most Earthlike planet we know. –Created at roughly the same time –Apparently similar bulk composition –Almost the same size & density –Similar solar energy input  (due to high reflectivity of Venus clouds). Early Venus was probably much like early Earth Hot dense atmosphere rich in CO 2 and water Venus also illustrates the probable fate of the Earth. In ~ 1 billion years, with a brighter sun, the insolation at Earth will be similar to that at Venus today. Will we be able to avoid the runaway greenhouse warming that is found at Venus? Need to understand the ‘life story’ of terrestrial planets

4. OXFORD RAS Venus meeting- 12 November 2010 Why Venus? Venus provides the key to understanding terrestrial planets (and exo-planets!). Venus allows study of the factors determining planetary habitaility: Radiative balance (greenhouse warming, role of clouds) Dynamics (role of super-rotation and equator-pole circulations in re-distributing heat) Evolution of atmospheric composition (surface-atmosphere and atmosphere-space exchanges) Role of magnetic field and solar wind interaction in governing escape rates. Which is the most common outcome for terrestrial planets: Venus-like, Earth-like, or Mars-like? Need to understand the ‘life story’ of terrestrial planets

5. OXFORD RAS Venus meeting- 12 November 2010 Why Venus? Venus balloons are easy! Cloud environment of Venus is Earthlike, with T ~ 20°C, p = 0.5 atm, liquid water (albeit acidic) Well-known atmospheric state from Venus Express; low risk for EDLS. Bright sunshine : ample solar power available. Extensive heritage (Technology demonstrated by Vega balloons flown in1984) Venus is the easiest planet to get to (only ~ 5 months cruise) Strong winds enable circumnavigation of the planet in 8-10 days.

6. OXFORD RAS Venus meeting- 12 November 2010 European Venus Explorer Timeliness The last in situ Venus mission was in 1984 – which will have been over 35 years ago by the time another one launches! Europe is currently in a leading position due to ESA’s Venus Express. Venus Express has raised many questions as to what occurs in the clouds and below (clouds are impenetrable to most wavelengths of the UV, visible and IR). Many processes in middle and lower atmosphere are still mysterious. – In situ sensing will increase the return from remote sensing datasets. (e.g. exact composition of cloud particles. With NASA’s focus on ‘Moon and Mars’, Venus has been neglected in NASA’s exploration. –Despite many proposals to NASA for Venus missions! The launch date of 2020-2022 allows time to develop enabling technologies. New technology allows more precise measurements and smaller instruments than the last generation of instruments from the 1970s.

7. OXFORD RAS Venus meeting- 12 November 2010 European Venus Explorer – A logical step in Venus exploration Step 1 (2005-2015) : European Venus-Express mission and Japanese Venus Climate mission Orbiter – Atmospheric and cloud dynamics – (Incomplete) global scale chemistry of the low atmosphere Step 2a (2015-2025) : in-situ mission, with the use of atmospheric probes (balloons, descent probes) –Venus climate evolution –New data relative to atmospheric isotopic ratios, chemistry of the coupled surface/ atmosphere system, dynamics of the whole atmospheric system. Step 2b (2015-2025) : Next-generation radar mission –Surface evolution –Landing site characterisaton Step 3 (2025-2035) : Long-lived landers for the characterisation of the interior structure and dynamics of Venus

8. OXFORD RAS Venus meeting- 12 November 2010 EVE - Science goals Evolution of Terrestrial planets and formation of the Solar System  How did Venus evolve?  How was the solar system formed?  Why did Venus, Earth and Mars evolve so differently?  How did Venus lose its water?  History of vulcanism? KEY MEASUREMENT REQUIREMENTS: - isotopic ratios of light elements: O, C, N, D/H - noble gas abundance measurements (Ar, Xe, Kr)  Serve as chronometers for evolutionary processe CO 2 and N 2 : Venus resembles Earth, but Mars is depleted by 3 orders of magnitude H 2 O : Venus is much dryer than Earth and Mars.

9. OXFORD RAS Venus meeting- 12 November 2010 EVE - Science goals Exploring the cloud-level environment –Uniquely Earth-like environment:  20°C ; 0.5 bar ; liquid cloud droplets of H 2 O : H 2 SO 4 –Clouds play an important (and poorly understood) role in radiative balance  reflect sunlight => cooling  block infrared emission => warming  As on Earth, clouds represent greatest uncertainty in greenhouse calculations  Clouds are highly variable; EVE can evaluate temporal & spatial variability of rad. balance –The cloud region (50-70 km) is the engine of the atmospheric circulation  The clouds are where 96% of the solar input is absorbed.  This is where the highest winds are found  This is the region which must be understood if we are to understand the circulation of slowly-rotating planets.  Vertical convective winds of±3 m/s – dynamic region with a lot to study. –The detailed composition of the clouds is as yet unknown  Main constituent is known to be H 2 SO 4 : H 2 O mix  Evidence for phosphorus, chlorine, and Iron in clouds from ambiguous Soviet XRF results  Complex and yet unknown chemistry  Search for volcanogenic gases  Search for lightning and its chmical products (e.g. NO ).

10. OXFORD RAS Venus meeting- 12 November 2010 EVE - Measurement goals Exploring the cloud-level environment –Chemistry –Microphysical properties –Dynamics –Radiative Balance –Electric properties Evolution of Venus & its climate –abundances of noble gases (Ar, Kr, Xe, …) and isotopic ratios of light elements (O,C, N …)

11. OXFORD RAS Venus meeting- 12 November 2010 EVE – Measurement goals Exploring the cloud-level environment –Chemistry –Microphysical properties –Dynamics –Radiative Balance –Electric properties Evolution of Venus & its climate –abundances of noble gases (Ar, Kr, Xe, …) and isotopic ratios of light elements (O,C, N …) GC/MS with Aerosol inlet; Tunable diode laser Nephelometer p, T, tracking of balloon (winds) 6-ch radiometer (↑ and ↓, λ = 0.25 – 25 μm) Permittivity, conductivity, electric charge of aerosol, lightning Dedicated mass spectrometer with getters, cryotraps Tunable diode laser to resolve ambiguities (e.g. CO vs N 2 ) + Cloud XRF

12. OXFORD RAS Venus meeting- 12 November 2010 EVE – baseline payload Instrument Mass (kg) Data rate 1 (bits/s) TRL (2007) Co-I InstitutionsHeritage GC/MS & ACP3.05304/5 Service d’Aeronomie / Open UnivRosetta, Huygens, Beagle2 Cloud XRF0.315Leicester Univ.Beagle 2, Bepi Colombo Isotopic ; Noble Gas MS 4.011.64/5 Open Univ / Service d’Aeronomie / U. Berne Rosetta, Beagle 2 TDL spectrometer155Service d’Aeronomie / NASA/JPLMars 2001 Lander, MPL Nephelometer / Cloud particle study 2.31.44 Cornell (USA) & TU Delft / U. Hertforshire / U. Manchester Venera, Vega, Pioneer Venus Optical package0.51.64+ Oxford UMars Climate Sounder Meteorological package 0.20.45 FMI / Oxford U / Padova Open U. / DLR Beagle 2 / ExoMars Accelerometers0.50.88 Open U / Padova / Imperial College Beagle 2, Huygens, ExoMars Electrical & EM package 0.710.06 Eötvös Univ / Reading / RAL / Oxford Compass-2, ISS TOTAL12.7561.8 ~ 15 kg payload inc. margin

13. OXFORD RAS Venus meeting- 12 November 2010 EVE 2010 vs. EVE 2007 EVE was proposed to ESA for CV 2007. –Orbiter + Balloon + Lander –Russia was to provide launcher, lander, and EDLS components EVE2007 made it through to the final 16, but not to the final 8 selected missions. –EVE was included in ESA’s Technology Development roadmap. –EVE2007 was viewed as very challenging given the cost cap of €300m cost to ESA. For CV2010, we propose: – A more tightly focussed mission, achievable without non-ESA partners – A balloon element only  Cruise vehicle provides data relay during flyby  Thereafter, balloon communicates Direct-to-Earth –More robust treatment of mass, power, and cost. CNES has been funding Phase 0 studies of EVE. Phase 0.1 (definition) – Oct 2009 – Jan 2010 Phase 0.2 (trade-offs) – Jan 2010 – June 2010 Phase 0.3 (detailed study) – July 2010 – Nov 2010 – Astrium (Toulouse) is studying a number of mission elements

14. OXFORD RAS Venus meeting- 12 November 2010 EVE 2010 – mission details Soyuz launch from Kourou – late 2021 or early 2023 –Launch opportunities occur every 19 months Carrier spacecraft to deliver descent module to Venus –190 day cruise (TBC) –Descent module: 620 kg entry mass He superpressure balloon, 5.8 m diameter –Float altitude : 55 km ± 3 km –Proven technology (c.f. Vega balloons: prototypes of 3.4 & 9.0 m  ) –Floating mass : 92 kg Lifetime of balloon: 10 days (1 complete circumnavigation of planet) Science payload mass : 15 kg incl margin Power: mix of Primary batteries & solar cells Communications : via Carrier spacecraft while visible (for initial detailed analyses), then direct-to-Earth (for long-term measurements).

15. OXFORD RAS Venus meeting- 12 November 2010 International collaboration EVE will be proposed as a mission which could be accomplished by ESA alone. International science team participation is welcome. Opportunities for internationally contributed instruments are possible –European providers should be identified for mission-critical instruments. Discussions underway with several partners about the possibility about providing an independent (but simultaneous) Venus orbiter, capable of data relay and orbital context measurements. –Russia –India

16. OXFORD RAS Venus meeting- 12 November 2010 EVE - UK Science opportunities EVE address many science questions in which UK is world-leading: –Geochemistry (isotopic ratio & noble gas signatures): Planetary & Sol. System evolution  Manchester  Oxford  NHM  Open Univ  Imperial College London  Lancaster –In situ instrumentation:  GC/MS – Open University  XRF of cloud particles – Leicester University  IR radiometry – Oxford University  meteorological instrumentation – Oxford & Open Universities  Electrical environment – Reading / RAL / Oxford  In situ cloud particle properties – Hertfordshire / Manchester / Oxford –Venus atmospheric modelling  Oxford  Open Univ  Imperial College EVE2007 had a science team of 180 international scientists Of these, 24 were from the UK.

17. OXFORD RAS Venus meeting- 12 November 2010 EVE - UK engineering opportunities The UK could play a leading part in some of the subsystems / instruments: Mass spectrometry (miniaturised and/or high-precision) In situ atmospheric measurements of meteorology and chemistry Balloon-deployed microprobes Each of the above could be led by a UK PI ! Indusrial opportunities for the UK: World-leading instruments & miniaturisation (e.g. Mass Spec., XRF) Phased antenna array for Venus-Earth comms w/ no moving parts. Carrier spacecraft Batteries, solar cells, accelerometers/gyros … Microprobes, (new micro-class mission element)

18. OXFORD RAS Venus meeting- 12 November 2010 European Venus Explorer Thanks for your attention http://www.univie.ac.at/EVE/