ESA’s Solar Orbiter will be the first spacecraft to study the sun’s polar zones

A new sungazing spacecraft has launched on a mission to chart the sun’s unexplored polar regions and to understand how our star creates and controls the vast bubble of plasma that envelops the solar system.

At 11:03 pm ET on February 9, the European Space Agency’s Solar Orbiter rocketed away from Cape Canaveral, Fla. The spacecraft now begins a nearly two-year convoluted journey — getting two gravity assists from Venus and one from Earth — to an orbit that will repeatedly take it a bit closer to the sun than Mercury gets.

Slated to study the sun for at least four years starting in November 2021, Solar Orbiter is going where few spacecraft have gone. The probe will soar above and below the orbits of the planets to get a peek at the sun’s north and south poles — a region no one has yet seen. One of the mission’s many goals is to see how the poles change when the sun’s magnetic field flips at the height of the next solar cycle, sometime in the middle of this decade.  

The probe carries a suite of 10 science instruments, including cameras and devices to measure the sun’s magnetic field and the solar wind, a stream of plasma that flows from the sun and eventually peters out at the solar system’s border with interstellar space (SN: 11/4/19). At Solar Orbiter’s closest approach to the sun, about 42 million kilometers above the surface, the sun will appear 13 times as bright as it does from Earth, heating the spacecraft to nearly 500° Celsius. To view the sun safely, most of its instruments will peek through protective windows tucked behind sliding doors in the spacecraft’s heat shield.

Solar Orbiter is part of a trifecta of new missions dedicated to unraveling the sun’s mysteries. NASA’s Parker Solar Probe is already spiraling closer and closer to the sun (SN: 12/4/19). Parker won’t ever view the sun directly or explore the poles, but it will get much closer than Solar Orbiter and directly measure the solar wind from just 6 million kilometers above the sun’s surface.

Meanwhile, the Daniel K. Inouye Solar Telescope in Hawaii — slated to be the largest solar telescope on Earth — will open for business this summer. It will provide a big picture view of the sun and its magnetic field with the highest resolution images yet taken (SN: 1/29/20).