Solar Orbiter

Solar Orbiter: High-Resolution Mission to the Sun and Inner Heliosphere addressing the Sun-Heliosphere and Sun-Earth connections

Solar Orbiter is a mission dedicated to solar and heliospheric physics. It was selected as the first medium-class mission of ESA's Cosmic Vision 2015-2025 Program and is scheduled for launch in February 2020.

The scientific rationale of the Solar Orbiter is to provide, at high spatial and temporal resolution, multi-wavelength observations of the solar atmosphere and comprehensive in-situ measurements of the unexplored inner heliosphere. By approaching the Sun as close as 0.28 AU (Astronomical Unit, the mean Earth to Sun distance), Solar Orbiter will view and diagnose the solar atmosphere with high spatial resolution and combine this with measurements of particles and fields made in-situ. Over its extended mission periods the Solar Orbiter will move out of the ecliptic plane to deliver images and related data that will cover the polar regions of the Sun. By its payload complement, Solar Orbiter will investigate the key topic of heliophysics: How does the Sun create and control the heliosphere?

The four main scientific questions addressed by the Solar Orbiter mission are:

  • How and where do the solar wind plasma and magnetic field originate in the corona?
  • How do solar transients drive heliospheric variability?
  • How do solar eruptions produce energetic particle radiation that fills the heliosphere?
  • How does the solar dynamo work and drive connections between the Sun and the heliosphere?

A selection of 10 instruments has been made for the scientific payload of the Solar Orbiter mission. This comprehensive suite of instruments will support multiple scientific investigations ranging from near-Sun and out-of-ecliptic in-situ measurements to remote-sensing observations of the Sun and its environment.



PHI: Polarimetric and Helioseismic Imager
PI: S.K. Solanki, Max-Planck-Institut für Sonnensystemforschung, Germany

full-disc photospheric vector magnetic field and line-of-sight (LOS) velocity as well as the continuum intensity in the visible wavelength range

EUI: Extreme Ultraviolet Imager
PI: P. Rochus, Centre Spatial de Liège, Belgium

simultaneous intermediate resolution full-disk and high-resolution partial-disk EUV image sequences of the solar atmospheric layers above the photosphere

Metis: Coronagraph
PI: M. Romoli, University of Florence, Italy

visible (polarized and unpolarized), and UV imaging of the solar corona

SPICE: Spectral Imaging of the Coronal Environment
Consortium Lead: A. Fludra, Rutherford Appleton Laboratory, UK

EUV imaging spectroscopy of the corona

SoloHI: Heliospheric Imager
PI: R. A. Howard, NRL, USA

visible sunlight scattered by solar wind electrons

STIX: X-ray Spectrometer/Telescope
PI: S. Krucker, FHNW, Switzerland

imaging spectroscopy of solar thermal and non-thermal X-ray emission

EPD: Energetic Particle Detector
PI: J. Rodríguez-Pacheco, University of Alcala, Spain

composition, timing and distribution functions of suprathermal and energetic particles

MAG: Magnetometer
PI: T. Horbury, Imperial College, UK

in situ measurements of the heliospheric magnetic field

RPW: Radio and Plasma Waves
PI: M. Maksimovic, Observatoire de Paris, France

magnetic and electric fields at high time resolution (in-situ and remote)

SWA: Solar Wind Plasma Analyser
PI: C. Owen, Mullard Space Science Lab, UK

ion and electron bulk properties (incl. density, velocity, and temperature) of the solar wind; ion composition for key elements of the solar wind


Solar Orbiter will be launched in February 2020 from Cape Canaveral aboard a NASA-provided launch vehicle. The space probe will reach its operational orbit 3 years after launch by using gravity assist manoeuvres at Earth and Venus.

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