Inside a solar storm inferno: NASA's Stereo-A spacecraft to "feel" a solar eruption

NASA spacecraft called STEREO-A will be visiting Earth after 17 long years of watching the Sun. Even as it does so, it will be passing inside a solar storm and sending the valuable data back to Earth to better chart our closest star. In effect, STEREO-A will be inside a solar eruption and that means it’s not just what STEREO-A will see as it flies by Earth, but also what it will “feel,” that could lead to major discoveries.

To put things in perspective, the Sun regularly spews out what is known as coronal mass ejection (CME). This is a vast amount of solar material that has the power of disrupting satellites, radio communications and even knocking out the power grid back on Earth. The STEREO-A spacecraft will now allow scientists to better study the phenomenon, from inside, as it will get to travel inside one that has been spewed out by the Sun.

Considering that CMEs are very dangerous for Earth, there is still much to be learned about them. Now STEREO-A presents a golden opportunity as it will likely be hit by a CME as it travels towards Earth. Yes, it will actually be inside a CME.

How important is it? Currently, the information is not as deep as it ought to be. “It's like the parable about the blind men and the elephant – the one who feels the legs says ‘it’s like a tree trunk,’ and the one who feels the tail says ‘it’s like a snake,’" said Toni Galvin, principal investigator for one of STEREO-A’s instruments. “That's what we're stuck with right now with CMEs.”

How it will work: NASA explains

When a plume of solar material known as a coronal mass ejection, or CME, arrives at Earth, it can disrupt satellite and radio signals, or even cause surges in our power grids.

Or, it may have hardly any effect at all. It all depends on the magnetic field embedded within it, which can change dramatically in the 93 million miles that it travels to the Earth.

NASA says that to understand how a CME’s magnetic field evolves on the way to Earth, scientists build computer models of these solar eruptions, updating them with each new spacecraft observation. But a single spacecraft's data can only tell us so much.

During the months before and after STEREO-A’s Earth flyby, any Earth-directed CMEs will pass over STEREO-A and other near-Earth spacecraft, giving scientists much-needed multipoint measurements from inside a CME.