The UK-built Solar Orbiter spacecraft has now begun its nearly two year journey towards the Sun to observe the Sun close-up and study its polar regions for the first time. It launched from Cape Canaveral on 10 February at 04:03am GMT, on board an Atlas V411 rocket. The mission will travel within the orbit of Mercury to get up close to the Sun, climb out of the ecliptic and give us the first clear view of the Sun’s poles. These observations will help us understand sources of the solar activity and discover how the Sun affects the heliosphere. The science phase of the mission is due to start in November 2021.

STFC’s RAL Space, University College London and Imperial College London have led international teams to design and build three of the 10 science instruments on board. UCL also contributed to the fourth instrument. The payload commissioning activities began two weeks after launch on 24 February. A brief status of the four instruments with the UK involvement is given below:

EUI: The Extreme Ultraviolet Imager (EUI) was developed by a consortium of 6 European groups. The Mullard Space Science Laboratory, University College London contributed the Common Electronics Box (CEB). The CEB was successfully powered on on 25th Feb. The “brains” of EUI manages the operation of all 3 EUI telescopes; the Full Sun Imager, the High Resolution Imager in Lyman alpha, and the High Resolution Imager in Extreme UltraViolet. The EUI camera switch-on will take place on 5 March, with the first light images expected at the end of April.

MAG: The magnetometer (MAG) from Imperial College London was successfully powered on to record data for boom deployment and was subsequently powered for a fully successful commissioning on the 24th of February. MAG remains on, recording solar wind data and measuring the magnetic signatures of other instruments as they undergo their commissioning activities. Preliminary analysis indicates that the instrument has the same excellent low noise levels measured during ground testing.

SPICE: The SPICE EUV spectrometer, developed and built by an international consortium led by STFC RAL Space, was switched-on in orbit for the first time on 24 February. All activities in the first three days of commissioning were successful, including basic checks on the Electronics Box, uploading a new set of on-board tables, and switching on the Contamination Monitoring System for the first contamination readings that show clean environment. SPICE has a 3-month commissioning schedule, with each subsystem to be tested individually before obtaining first calibration data.

SWA: The 3 sensors in the SWA suite remain switched off, as planned, to allow sufficient outgassing before powering up the various high-voltage systems. The SWA DPU box will be powered up on March 4th for a flight software update, and commissioning proper begins on March 9th, and lasts for several weeks, first with step-by-step turn on of the heavy ion sensor, then the proton and alpha particle sensor and finally the electron analyser system.

Andrzej Fludra, Tim Horbury, David Long, Chris Owen