Solar Orbiter

Mission Overview

Solar Orbiter was selected as the first element in the European Space Agency (ESA) Cosmic Vision 2015-2025 programme in October 2011.  Following the launch, in February 2020, the Solar Orbiter spacecraft has orbited the Sun once every ~6 months.  A series of gravitational assist manouevres at the Earth and Venus (EGAM/VGAM) have lowered the closest approach to the Sun to 0.28 AU (1 AU – an astronomical unit – is the distance of the Earth from the Sun).  In February 2025 a VGAM occurred which started to raise the plane of the orbit out of the ecliptic, such that the spacecraft will reach higher and higher heliocentric latitudes (~34° by the end of the mission).  The near-Sun distances allow the spacecraft to orbit the Sun with a reduced angular speed relative to the solar rotation (~25.5 days), such that individual active regions on the surface, will remain beneath the spacecraft and visible to the remote sensing instruments for an extended period of time.  The tilted plane of the orbit will allow a more detailed view of the poles of the Sun and enhanced sampling of the solar wind emitted from these regions.

The spacecraft carries a payload comprising 10 separate instruments, or suites of instruments. These can be divided into two groups:  (i) The remote sensing instruments, which are tasked to observe the dynamics of the Sun and its surface layers in a variety of different wavelengths and through a variety of techniques; (ii) the in situ instruments which will study the particles, fields and waves fields in the solar wind immediately above those source regions on the Sun which are monitored by the remote sensing instruments.