1. Seminar in association with the MEDOC 12 campaign, Nov 2003 Solar Orbiter Work of the ESA/NASA Solar Orbiter Study Team Presented by Alan Gabriel, IAS

2. Seminar in association with the MEDOC 12 campaign, Nov 2003 Unique properties of the Solar Orbiter mission  Explore in situ the uncharted innermost regions of our solar system  Observe by remote sensing the Sun from close- up (45 solar radii)  Orbit the Sun tuned to its rotation and examine the solar surface and the space above from a co- rotating vantage point  Provide images of the Sun’s polar regions from heliographic latitudes in excess of 30°

3. Seminar in association with the MEDOC 12 campaign, Nov 2003 Orbit Earth departure 1.5 Earth swing-by Subsequent Venus swing-by’s First Venus swing-by  Closer to the Sun  Out of the ecliptic

4. Seminar in association with the MEDOC 12 campaign, Nov 2003 Mission profile - Spacecraft heliographic latitude

5. Seminar in association with the MEDOC 12 campaign, Nov 2003 Mission Profile - Perihelion distance

6. Seminar in association with the MEDOC 12 campaign, Nov 2003 Mission Profile - Relative angular speed

7. Seminar in association with the MEDOC 12 campaign, Nov 2003 Four main scientific goals With Solar Orbiter we will, for the first time: A. Determine the properties, dynamics and interactions of plasma, fields and particles in the near-Sun heliosphere B. Investigate the links between the solar surface, corona and inner heliosphere C. Explore, at all latitudes, the energetics, dynamics and fine-scale structure of the Sun’s magnetized atmosphere D. Probe the solar dynamo by observing the Sun’s high-latitude field, flows and seismic waves

8. Seminar in association with the MEDOC 12 campaign, Nov 2003 Q: Plasma, field and particles......  What is the character and radial evolution of solar wind structures in the inner heliosphere?  What is the nature of solar wind stream interactions in the inner heliosphere, and how does it depend on latitude?  What is the influence of CMEs on the structure of the inner heliosphere?  What is the nature of particle acceleration and transport in the near-Sun environment?  What is the role of shocks and flares in accelerating particles near the Sun?  How does the solar wind microstate evolve with radial distance?

9. Seminar in association with the MEDOC 12 campaign, Nov 2003 Kinetics of the solar wind Plasma microstate Temperature anisotropies Ion beams Plasma instabilities Interplanetary heating Solar Orbiter will make high-resolution ion and electron measurements Solar wind protons (Helios)

10. Seminar in association with the MEDOC 12 campaign, Nov 2003 Turbulence near the Sun Magnetohydrodynamic waves and turbulence Spectrum of Alfvénic fluctuations Steepening and dissipation! Solar Orbiter will show how MHD turbulence varies and evolves spatially what generates Alfvén waves in the corona how the turbulence is dissipated

11. Seminar in association with the MEDOC 12 campaign, Nov 2003 Tracing of energetic particles Solar Orbiter will provide novel information on shock, flare and CME related particle acceleration, by virtue of proximity to the Sun (particles less influenced by transport effects) co-rotating orbit (long-term magnetic linkage) imaging of source regions timing from tracing radio emissions

12. Seminar in association with the MEDOC 12 campaign, Nov 2003 Co-rotation observations Boundaries and interfaces Solar Orbiter will determine relationships between coronal and solar wind structures on all scales correlate in-situ particle characteristics with their coronal sources identify plasma boundaries and coronal origins

13. Seminar in association with the MEDOC 12 campaign, Nov 2003  Sun, most powerful accelerator in solar system  Protons up to 10’s GeV  Electrons up to 100’s MeV  Flares, powerful explosions  Energy release up to 10 32 - 10 33 erg in 10 -10 3 s.  Flare accelerated 10 -100 keV electrons and 1 MeV ions contain 10 - 50% of the energy  Hierarchy of flare processes, relevant for coronal heating Sun as accelerator

14. Seminar in association with the MEDOC 12 campaign, Nov 2003 Tracing boundaries by minor ions

15. Seminar in association with the MEDOC 12 campaign, Nov 2003 Q: Linking sun and heliosphere.....  How does the evolution of the solar magnetic field affect the heliosphere at all scales?  What are the sources of the slow solar wind, and what is its temporal and spatial evolution?  What are the sources and the global dynamics of eruptive events and what are their effects on the inner heliosphere?  What are the relevant physical processes that lead to turbulence in the tenuous magnetofluid of the inner heliosphere, and how does this turbulence interact with heliospheric particles?  What is the solar source of the solar wind plasma (including that of CMEs) and energetic particles seen in the interplanetary medium (IPM)?  What regions at the Sun are the sources of the magnetic field lines in the IPM?

16. Seminar in association with the MEDOC 12 campaign, Nov 2003 Solar wind sources SOHO: The fast solar wind flows from supergranulation cell boundaries in polar coronal holes The Solar Orbiter will provide: appropriate line-of-sight for detailed analysis of the polar outflows passages into different wind regimes and across flow boundaries co-rotation, enabling steady magnetic linkage

17. Seminar in association with the MEDOC 12 campaign, Nov 2003 Linking corona and heliosphere Global solar corona and solar wind SOHO Solar Orbiter will enable us to link specific sources to their in-situ manifestations and to discriminate between spatial and temporal variations, especially through co-rotation observations Ulysses

18. Seminar in association with the MEDOC 12 campaign, Nov 2003 Magnetic field modelling Accompanying modelling efforts for the solar magnetic field will allow us to: better identify and track solar magnetic features on all scales better establish the magnetic linkage between the corona and inner heliosphere

19. Seminar in association with the MEDOC 12 campaign, Nov 2003 Q: Sun’s dynamic atmosphere....  How is the polar high-speed wind generated and how does this relate to the polar plume phenomenon?  How does the structure and evolution of polar coronal hole regions project into the inner heliosphere?  What is the nature of coronal hole boundaries, how do they evolve and how do they project into the inner heliosphere?  What is the nature of fundamental processes in the Sun’s atmosphere, including wave activity from source to the corona, the physics of transient events and flux emergence, over all latitudes?

20. Seminar in association with the MEDOC 12 campaign, Nov 2003 Resolving fundamental scales Due to proximity, Solar Orbiter will resolve scales such as the photon mean free path, barometric scale height and flux tube diameters in the photosphere (~100 km) SOHO/EIT TRACE Solar Orbiter 1850 km pixels 350 km pixels 35 km pixels

21. Seminar in association with the MEDOC 12 campaign, Nov 2003 Plasma dynamics in loops TRACE 350 km pixel imaging Solar Orbiter will provide: - plasma diagnostics, Doppler shifts and broadenings, and images, - both an order of magnitude better resolution (35 km and 75 km) than currently available

22. Seminar in association with the MEDOC 12 campaign, Nov 2003 Q: Sun’s polar magnetic field...  How does the high-latitude field of the Sun evolve on a range of scales?  What are the properties of the Sun's surface and sub- surface meridional flow and differential rotation at high latitude, and how do these vary with time and position?  Is there a second cell in the meridional flow near the poles?  What are the properties of emerging flux at high latitudes?  Is the sub-surface polar “jet-stream” real or not?  What are the signatures of the solar dynamo action near the bottom of the convective envelope?

23. Seminar in association with the MEDOC 12 campaign, Nov 2003 Polar convection and dynamo Solar Orbiter will allow us to study the: magnetic structure and evolution of the polar regions detailed flow patterns in the polar regions development of sub-surface magnetic structures using local-area helioseismology at high latitudes

24. Seminar in association with the MEDOC 12 campaign, Nov 2003 Out of ecliptic study of the corona Solar Orbiter will allow studies of: longitudinal spreads, structure and directions of CMEs, streamers etc… the entire equatorial corona current sheets at all latitudes the global distribution of CMEs and their 3-D structure

25. Seminar in association with the MEDOC 12 campaign, Nov 2003 Exploratory measurements  First in-situ detection of neutral (hydrogen) atoms from the Sun  First measurement of near- Sun dust (e.g., from sun- grazing comets)  First detection of low-energy solar neutrons from flares

26. Seminar in association with the MEDOC 12 campaign, Nov 2003 Q: Dust, neutrals and neutrons....  What are the sources and properties of dust in the inner heliosphere. Do Sun-grazing comets contribute to the dust?  What is the role played by the near-Sun dust for the interplanetary pick-up ions?  What are the fluxes and spectra of low-energy solar neutrons?  Can one probe remotely nuclear reactions and ion acceleration on the Sun?  Is there a neutral solar wind, and what are its properties?  How does the solar corona look like when being imaged by energetic neutral atoms?  How does the solar luminosity vary, and does it change globally (depend on latitude)?

27. Seminar in association with the MEDOC 12 campaign, Nov 2003 Science Definition Team (SDT) Chair: E. Marsch. The SDT is currently:  reviewing the scientific goals of the mission as presently understood  refining these goals where needed  prioritising them in order to achieve a well-balanced, and highly focused scientific mission  defining the sets of measurements needed (baseline and minimum) to achieve the mission’s scientific goals, taking into account the output of the Payload Working Group  Output: Science Requirements Document to be completed by SDT in November 2003

28. Seminar in association with the MEDOC 12 campaign, Nov 2003 Baseline mission (SDT) InstrumentMass kg Power W Rate kbps Plasma Package (SWA)15.51114 Fields Package (MAG +RPW + CRS)11135.8 Particles Package (incl. Neutrons,gammas & dust) 15 4.5 Visible Light Imager & Magnetograph (VIM) 302520 EU Imager (3 telescopes incl. FSI)302520 EU Spectrometer25 17 Spectrometer/Telescope Imaging X- rays (STIX) 4 40.2 Coronagraph (COR)10 7 Total140.512888.5

29. Seminar in association with the MEDOC 12 campaign, Nov 2003 Summary q The exciting mission concept for Solar Orbiter has led to intensive studies demonstrating technical feasibility of this challenging mission and a strong scientific and multinational desire to realise it in a timely manner. q Solar Orbiter offers unique scientific opportunities for:  Exploration of unknown territory near the Sun  Investigation of the solar poles  Observations of the Sun at unprecedented high resolution  Understanding the links between Sun and heliosphere q Given such a strong scientific case, we believe that Solar Orbiter is an indispensable part of ESA’s future science programme.

30. Seminar in association with the MEDOC 12 campaign, Nov 2003

31. Comparison with other missions The multi-national solar/heliospheric strategy  We have SOHO (ESA/NASA) – the World‘s flagship solar observatory  We had Helios and have Ulysses (ESA), together providing solar wind data to 0.3 AU in the ecliptic, and over all latitudes beyond 1 AU – neither with remote sensing  We had Yohkoh (ISAS) and have TRACE (NASA) providing solar X-ray and UV imaging  What next?

32. Seminar in association with the MEDOC 12 campaign, Nov 2003 Comparison with other missions In the Solar Orbiter time-frame (launch 2011/12):  SOHO, TRACE, Ulysses missions will be over  STEREO, Solar-B missions likely to be complete  Solar Dynamics Observatory (SDO) may be operational However, Solar Orbiter will open a new research chapter, because:  The orbit is unique  exploration and potential revelations  No solar imaging mission has yet ‘encountered’ the Sun or climbed out of the ecliptic  unprecedented views