Solar Orbiter is a joint ESA/NASA collaboration that will address a central question of heliophysics: How does the sun create and control the giant bubble of magnetic fields around it, the heliosphere?
Solar Orbiter has been placed into an elliptical orbit around the sun coming as close to 26 million miles away from the star every five months -- even closer than Mercury. It will take three years to reach this orbit. When travelling at its fastest, Solar Orbiter has remained positioned over approximately the same region of the solar atmosphere as the sun rotates on its axis, allowing unprecedented observations. The inclined orbit has allowed Solar Orbiter to better image the regions around the sun’s poles than ever before.
Solar Orbiter makes in-situ measurements of the solar wind plasma, fields, waves, and energetic particles by traveling closer to the sun than the previous record-holders, Helios 1 and 2 – traveling nearly three-quarters of the way to the sun, a journey of approximately 67 million miles. At that distance, Solar Orbiter has been able to observe solar processes that are still relatively pristine and have not had their properties modified by subsequent transport and propagation processes.
On 27 December 2020, Solar Orbiter completed its first Venus flyby. By the end of 2021 all instruments will be working together in preparation to approach the sun. In 2022, Solar Orbiter will close to within 48 million kilometers of the Sun's surface, more than 20 million kilometers closer than it will go in 2021.