‘We don’t know how bad it could get’: Are we ready for the worst space weather?

Imagine being told a storm is heading your way, but you won’t know how bad the winds are or whether they’ll knock out power until just minutes before it hits. That’s the challenge scientists face when it comes to predicting solar storms.

We’ve come a long way in understanding space weather. We can spot solar storm eruptions, track their speed, and estimate when they’ll arrive at Earth, sometimes with up to a day’s warning. However, one critical piece of information remains frustratingly out of reach until the last moment: the orientation of the storm’s magnetic field, known as the Bz component.

When a coronal mass ejection (CME) erupts from the sun, it carries with it plasma and magnetic field from our star. The orientation of the magnetic field will either be a northward or southward Bz, or a combination of the two, and that magnetic orientation determines how strongly the incoming solar storm will interact with Earth’s magnetic field. A southward Bz connects more easily with Earth’s own field, allowing energy to pour in and supercharge auroras — or in extreme cases, disrupt satellites, radio signals, power grids, and GPS. A northward Bz, on the other hand, may pass by with minimal impact.

Scientists say knowing the Bz component of an oncoming CME can make a significant difference in helping us prepare for the effects of a solar storm. “We need to start predicting what Bz is going to be as soon as the CME has occurred, not when we measure it at L1 [Lagrange 1], where we only have one or two hours’ warning,” Valentín Martínez Pillet, solar physicist and director of the Instituto de Astrofísica de Canarias told Space.com in an interview while attending science and music festival Starmus La Palma.

We have the science — what we’re missing is data

Martínez Pillet predicts it will take about 50 years for space weather forecasting to reach the same accuracy and predictability as Earth weather predictions.

“We are getting close,” Martínez Pillet says. “Operational predictions from the NOAA Space Weather Prediction Center (SWPC) are good, but what we’re missing is more data from all sides of the sun.”

Most of our current monitoring comes from a single vantage point: spacecraft located around Lagrange Point 1 (L1), roughly 1 million miles (1.5 million kilometers) sunward of Earth. These spacecraft, like NASA’s ACE and DSCOVR missions, can detect solar wind properties and measure Bz — but only when the storm is already nearly upon us. At that point, there is just one or two hours’ advanced warning.

To truly forecast the strength of a solar storm before it hits, we need to take measurements earlier, much earlier. Ideally, we would perch satellites at a variety of Lagrange points, not just L1, to allow us to view these magnetic structures while they’re still leaving the sun.

“The models are there, so we know the equation we have to solve, but we don’t have good data,” Martínez Pillet says.

Parking sun-observing satellites at L5, L4 and L3 won’t be cheap, but it is very much possible, according to Martínez Pillet.

“We’re going to have it. I’m totally convinced that that’s where we’re heading,” Martínez Pillet said.

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