On June 15 2020, ESA’s new Sun-explorer Solar Orbiter reached its first perihelion, the point on its orbit closest to the Sun.
The spacecraft got as close as 77 million kilometres to the star’s surface during this perihelion, about half the distance between Earth and the star.
All of the spacecraft’s ten scientific instruments were on during the week around the closest approach, measuring properties of the surrounding environment, such as the magnetic field and the solar wind, but also taking close-up images of the Sun’s surface.
No other spacecraft before had taken closer images of the Sun, even though NASA’s Parker Solar Probe, launched in 2018, makes closer approaches. The spacecraft, however, doesn’t carry instruments capable of looking directly at the Sun. Ground-based telescopes can obtain higher resolution images, but due to the effects of Earth’s atmosphere cannot capture the entire solar spectrum.
The first perihelion also marked the end of Solar Orbiter’s commissioning phase and the beginning of the cruise phase, which will last until late 2021. During the science phase that follows, the spacecraft will get as close as 42 million kilometres to the Sun’s surface, closer than the planet Mercury.
The spacecraft’s operators will then use the gravity of Venus to shift Solar orbiter’s orbit out of the ecliptic plane, in which the planets of the Solar System orbit, to enable the telescopes to get the first ever proper views of the Sun’s poles. Studying the activity in the polar regions will help the scientists to better understand the behaviour of the Sun’s magnetic field, which drives the creation of the solar wind that in turn affects the environment of the entire Solar System.