1. Solar Orbiter Exploring the Sun-heliosphere connection
Science questions
Mission overview
Status update
Introduction, structure of the talk

2. The Sun creates the heliosphere
Sun and solar system live in interstellar space
Sun’s hot atmosphere corona blows off into space as the solar wind, carving a cavity known as the heliosphere
Left: Hubble image of a young star’s heliosphere and bowshock in the Orion nebula
Right: coronagraph movie from SoHO. Speeded up but shows fine scale structure as well as large scale, related to global magnetic field. It is this

3. Why study the Sun-space connection?
Addresses ESA’s Cosmic Vision question “How does the solar system work?”
Study plasma phenomena which occur throughout the Universe
Shocks, particle acceleration, magnetic reconnection, turbulence, etc.
Also addresses Cosmic Vision question “What are the fundamental physical laws of the Universe?”
Solar wind and energetic particles directly affect life on Earth
Impact on space and ground-based assets
Builds on European heritage: Ulysses and SoHO
Just read through this. This is large scale motivation for the mission, including CV relevance, societal impact and European heritage

4. The need for near-Sun observations
In-situ density
Solar Orbiter
Distance
Why go close to the Sun? Variable and structured solar wind parcels collide and coalesce, smoothing out structures. Talk through figure.
Solar Orbiter will go close enough that this has not significantly occurred
Solar Orbiter 1 2 3 4 5 6
Days

5. Tu, Zhou, Marsch et al., Science 2005
How and where do the solar wind plasma and magnetic field originate in the corona?
Solar wind is variable and structured
Originates in complex magnetic “carpet”
Small scale transient jets are common
polar coronal hole
coronal funnel
Tu, Zhou, Marsch et al., Science 2005
Solar Orbiter will measure the spatial and temporal variability of the solar source and solar wind in unprecedented detail

6. Linking Sun and the solar wind
We need to measure the same parameter on the Sun and in space to make the link
Heavy ion charge states and composition
Magnetic polarity
Energetic particles
Solar Orbiter will make all of these measurements with both remote sensing and in situ instruments
He+ H+

7. How do solar transients drive heliospheric variability?
How are substructures of coronal mass ejections related to interplanetary transients?
How are CMEs processed as they travel from the Sun?
Solar Orbiter will image CMEs and measure their evolution in the inner heliosphere

8. Coronal mass ejections in space

9. How do solar eruptions produce energetic particle radiation?
Around 10% of coronal mass ejection energy is in accelerated particles
Understanding release and transport mechanisms requires going close to the Sun
Solar Orbiter will measure energetic particles within a mean free path of their acceleration site
0.3 AU
1.0 AU

10. How does the solar dynamo work?
The unexplored poles are central to the operation of the Sun’s dynamo
Solar Orbiter will provide the first accurate measurements of polar flows and magnetic fields

11. The Sun has changed

12. What is required Close to the Sun Out of the ecliptic
Long duration observations of the same region
Remote measurements of the Sun and corona
In situ measurements of fields and particles
It is this unique combination provided by Solar Orbiter that makes it possible to address the question of how the Sun creates and controls the heliosphere

13. Summary
Carefully optimised payload of ten remote sensing and in situ instruments
Launch: January 2017
Cruise Phase: 3 years
Nominal Mission: 3.5 years
Extended Mission: 2.5 years
Perihelion: 0.28 – 0.3 AU
Fast perihelion motion: solar features visible for almost complete rotation
Out of ecliptic: first good view of solar poles

14. Mission profile

15. Solar Orbiter spacecraft
Three-axis stabilised, Sun pointing
Heatshield at front
Re-use of BepiColombo unit designs as practical
Mass: 1750kg
Power: 1100W
Launch: ELV

16. Remote sensing instruments
In situ instruments
SWA
Solar wind analyser
Chris Owen, UK
Sampling protons, electrons and heavy ions in the solar wind
EPD
Energetic particle detector
Javier Rodriguez-Pacheco, Spain
Measuring timing and distribution functions of accelerated energetic particles
MAG
Magnetometer
Tim Horbury, UK
High-precision measurements of the heliospheric magnetic field
RPW
Radio and plasma wave analyser
Milan Maksimovic, France
Studying local electromagnetic and electrostatic waves and solar radio bursts
Remote sensing instruments
PHI
Polarimetric and heliospheric imager
Sami Solanki, Germany
Full-disc and high-resolution visible light imaging of the Sun
EUI
Extreme ultraviolet imager
Pierre Rochus, Belgium
Studying fine-scale processes and large-scale eruptions
STIX
Spectrometer/telescope for imaging X-rays
Arnold Benz, Switzerland
Studying hot plasmas and accelerated electrons
METIS
Multi-element telescope for imaging and spectroscopy
Ester Antonucci, Italy
High-resolution UV and extreme UV coronagraphy
SoloHI
Solar Orbiter heliospheric imager
Russ Howard, US
Observing light scattered by the solar wind over a wide field of view
SPICE
Spectral imaging of the coronal environment
Facility instrument, ESA provided
Spectroscopy on the solar disc and corona

17. SPICE and SIS
ESA tasked external review committee to study scientific impact of NASA decision not to support SPICE and SIS
Committee urged ESA to investigate ways to recover measurement capabilities of SIS and SPICE

18. SPICE – UV imaging spectrograph
Returns 2D high resolution spectral images
Intensity, Doppler shift, line width
Complete temperature coverage from chromosphere to flaring corona
Provides remote characterisation of plasma properties near the Sun
Map outflow velocities and composition of surface features to solar wind structures

19. SPICE - status Proposal exists for provision of SPICE instrument
Retains Red Book capabilities
Full on disk capabilities
Off-limb up to 1.3 solar radii
METIS augments this with off-limb spectroscopy beyond 1.3 solar radii
All mission science goals achieved

20. SIS – Supra-thermal ion spectrograph
Measures supra-thermal heavy ions
Part of EPD suite
Covers energy range between solar wind and energetic particles
Explores near-Sun ion pool, plus flares and shocks

21. SIS - status Proposal exists for provision of SIS instrument
Retains Red Book capability
All mission science goals achieved

22. Science windows High-latitude remote sensing Orbit: 150-168 days
Perihelion remote sensing
High-latitude remote sensing
Science windows
Orbit: days
In situ instruments on at all times
Three science “windows” of 10 days each
All remote sensing instruments operational
Observing strategies based on science targets
Active regions, coronal hole boundaries, flares, high speed wind, polar structures
Autonomous burst mode triggers for unpredictable events
Telemetry and mass memory tailored to return planned instrument data volumes

23. Links to Solar Probe Plus
Many conjunctions will occur between Solar Orbiter and Solar Probe Plus
Extends science return from both msisions
Solar Probe Plus is not required for any Solar Orbiter science goal

24. Solar Orbiter
Answers the Cosmic Vision question “How does the solar system work?”
Unique combination of orbit and instruments
Selected payload is optimised answer the most fundamental questions of solar and heliospheric physics
Timely, mature and well studied mission with compelling scientific objectives