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

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

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

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

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

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+

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

Coronal mass ejections in space

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

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

The Sun has changed

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

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

Mission profile

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

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

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

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

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

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

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

Science windows High-latitude remote sensing Orbit: 150-168 days Perihelion remote sensing High-latitude remote sensing Science windows Orbit: 150-168 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

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

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