A NASA-supplied Atlas 5 rocket launched the European Space Agency’s Solar Orbiter spacecraft 9 February, kicking off an innovative mission to study the Sun in unprecedented detail, complementing close-in observations by NASA’s Parker Solar Probe while giving scientists their first looks at the star’s polar regions.
The long-awaited mission marks “the first time that we (have sent) a satellite out to take images of the Sun’s poles and in addition, getting the first ever data of the polar magnetic field,” said ESA Project Scientist Daniel Mueller. “We believe this really holds the keys to unraveling the mysteries of the Sun’s (11-year) activity cycle.
“We will also monitor the far side of the Sun, which we cannot see from Earth, and combine that with data from satellites and ground-based telescopes to provide a full 3D view of our star,” he added. “And so the orbiter is really a laboratory, we have a suite of 10 sophisticated instruments that we will (work) together to track the evolution of eruptions on the Sun from the surface out into space, all the way down to Earth.”
The Atlas 5’s Centaur upper stage released the Solar Orbiter on an Earth-escape trajectory that will carry it past Venus in late December for the first in a series of gravity-assist flybys. The flybys are designed to change the probe’s course and put it into an elliptical orbit around the Sun that will repeatedly carry it closer to the star than Mercury.
The flybys also will tilt the orbit with respect to the Sun’s equator, giving the Solar Orbiter a direct view of the star’s poles. The initial “polar pass,” at an elevation of about 17 degrees, is expected in march 2025. By July 2029, the tilt will reach more than 33 degrees.
The Solar Orbiter mission follows on the heels of the Parker Solar Probe, flying in an elliptical orbit that periodically flies through the sun’s corona. Extreme temperatures preclude the use of sun-facing cameras, but Parker is equipped with a suite of other instruments to study the Sun’s magnetic fields, the supersonic solar wind and the mechanisms that heat the corona to millions of degrees.
The Solar Orbiter will within 26 million miles of the sun, far enough out to enable cameras and telescopes, looking through “peepholes” in the spacecraft’s thick heat shield, to capture what should be spectacular views.
Along with four “in situ” instruments to study the solar wind and nearby space environment, “we have six telescopes that observe the light from the sun in different parts of the rainbow spectrum,” Mueller said. “Two of those are so called coronagraphs where we block out the light of the sun itself to image the faint emission of the environment around the sun, the so called corona.
“In addition, we have these sensors that measure, for example, ions in space. Elements on the sun are not only hydrogen and helium, but also sprinkling of heavier elements like iron, oxygen, neon. We measure those at the location of the spacecraft, we really weigh the particles, but we can also measure the light that they emit on the surface and thereby we have a unique way of linking the two.”
If all goes well, the Solar Orbiter and the Parker Solar Probe will be able to study the Sun at the same time from different vantage points, providing a more complete picture of the processes at work on and deep inside the star.
Said Guenther Hasinger, director of science for the European Space Agency: “It’s really a perfect dream marriage (made) in heaven.”