To perform close-up, high-resolution studies of our Sun and inner heliosphere, ESA‘s Solar Orbiter is intended to brave the fierce heat and carry its telescopes to just one-fifth of Earth’s distance from our nearest star.ESA’s Solar Orbiter mission is conceived to perform a close-up study of our Sun and inner heliosphere – the uncharted innermost regions of our Solar System- to better understand, and even predict, the unruly behaviour of the star on which our lives depend. At its closest point, the spacecraft will be closer to the Sun than any previous spacecraft, braving the fierce heat and will carry its telescopes to almost one-fifth of Earth’s distance from our nearest star. It will provide unique data and imagery of the Sun.
Solar Orbiter will be the first satellite to provide close-up views of the Sun’s polar regions, which are very difficult to see from Earth, providing images from latitudes higher than 30 degrees. It will be able to tune to the Sun’s rotation around its axis for several days, and so it will be able for the first time to see solar storms building up over an extended period from the same viewpoint. It will also deliver data of the side of the Sun not visible from Earth.
At nearly one-fifth of Earth’s distance from the Sun, Solar Orbiter will be exposed to sunlight 20 times more intense than what we feel on Earth. The spacecraft must also endure powerful bursts of atomic particles from explosions in the solar atmosphere.
To withstand the harsh environment and extreme temperatures, Solar Orbiter must be well equipped. It will exploit new technologies being developed by ESA for the mission BepiColombo to Mercury, the planet closest to the Sun. This includes high-temperature solar arrays and a high-temperature high-gain antenna.
When travelling at its fastest along its orbit around the Sun, Solar Orbiter will be able to remain positioned over approximately the same region of the solar atmosphere, as the Sun rotates on its axis. It will be the first time in the history of solar exploration that this will be achieved by a solar spacecraft. Just as geostationary weather and telecommunications satellites are stationed over particular spots above Earth’s surface, so the spacecraft will seem to ‘hover’ for a while over the Sun. Solar Orbiter will therefore be able to watch storms building up in the atmosphere over several days.
Solar Orbiter is specially designed to always point to the Sun, and so, its Sun-facing side is protected by a sunshield. The spacecraft will also be kept cool by the positioning of special radiators, which will dissipate excess heat into space. The solar arrays and the communications system are inherited from the design of ESA’s BepiColombo mission to Mercury.
Following launch, currently foreseen for 2015, Solar Orbiter will begin its journey to the Sun. This will require a cruise phase lasting approximately 3.4 years. During this time, the instruments will be commissioned, and some in-situ data will be acquired. During the cruise, Solar Orbiter will use gravity assists from Venus and the Earth. These swing-bys will put Solar Orbiter into a 150-day-long orbit around the Sun from which the spacecraft will begin its scientific mission.