Solar Orbiter mission takes off towards its orbit around the Sun

On February 9 will be launched, from Cape Canaveral (Florida, United States), the Solar Orbiter mission, developed by the European Space Agency (ESA) with the participation of NASA. Solar Orbiter will revolve around the Sun in an orbit with a minimum distance less than that of Mercury and outside the ecliptic, which will provide with a unique perspective and allow it to observe the Sun's poles. In addition, its instruments will take local and remote measurements, which will provide the first complete vision of both solar and heliospheric physics.

“This mission highlights the excellent position of our country in solar and heliospheric physics and in technological development for space. This is the first time that Spanish teams are at the head of two instruments aboard a space mission, in this case SO/PHI and EPD, co-led respectively by the Institute of Astrophysics of Andalusia (IAA-CSIC) and by the University of Alcalá”, says Jose Carlos del Toro, IAA-CSIC researcher and co-Principal Investigator of SO/PHI.

During the initial cruise phase, which will last until November 2021, Solar Orbiter will perform two gravitational assistance maneuvers around Venus and one around Earth to raise its orbital plane and access high latitudes, allowing it to obtain the first quality view of the magnetic field at the poles. At the same time, the mission will acquire in situ data and characterize and calibrate its remote-sensing instruments. The first approach to the Sun will take place in 2022, at about one third of the distance between the Earth and the Sun, and in its closest orbits it will be about forty-two million kilometres from the Sun, a distance somewhat less than that of Mercury.

The Solar Orbiter mission is ahead of its predecessors because it will address both the study of the Sun and the interplanetary environment: it will observe how the Sun influences its surroundings and what is the origin of that influence. In addition, it will provide the first quality view of the polar magnetic field, which is fundamental for understanding the change in magnetic polarity that takes place in the Sun every eleven years and whose functioning is unknown. Finally, the mission will use the technique of helioseismology to know what happens inside the Sun.

SO/PHI: THE MAGNETIC FIELD IN DETAIL
The Institute of Astrophysics of Andalusia (IAA-CSIC) co-leads the development and construction of the largest scientific instrument on board the spacecraft, the Polarimetric and Helioseismic Imager (PHI). Its objective lies in the realization of an accurate mapping of the solar magnetic field, responsible for most of the phenomena that we observe in the Sun, such as spots, solar storms or solar wind (a continuous flow of electrically charged particles emanating from the Sun which travel through interplanetary space). SO/PHI will also measure the plasma velocity in the photosphere, the innermost layer of the Sun's atmosphere and where the solar wind comes from.

"The important contribution of Spain to SO/PHI is a success thanks to the close collaboration between national institutes with long-term planning, specifically during the last eighteen years," says Alberto Álvarez Herrero, the researcher responsible at the National Institute of Aerospace Technology (INTA). "The result is that some key technologies for this instrument are Spanish contributions, such as the innovative optical systems we have developed."

SO/PHI is also unique because, instead of sending the original data, it will do science on board: a device designed at the Institute of Astrophysics of Andalusia (IAA-CSIC), with a speed greater than that of about fifty computers working on in parallel, will convert those measurements into maps of the solar physical magnitudes; the first ones will be destroyed to free memory and the second ones will be sent to Earth.

SO/PHI has been developed by an international consortium (45% Germany, 42% Spain, 10% France and the rest other countries). The coordination of the Spanish part is carried out from the IAA-CSIC, with the participation of the National Institute of Aerospace Technology (INTA), the University of Valencia, the Ignacio da Riva Microgravity Institute of the Polytechnic University of Madrid, the University from Barcelona and the Institute of Astrophysics of the Canary Islands.