Spacecraft used to forecast solar storm 15 hours before it hit Earth

One day we could provide powerful solar storms capable of devastating earth electronics more than half a day in advance, following a successful test of the approach using the solar orbit spacecraft.

The sun occasionally releases powerful plasma explosions called coronal mass ejections (CME), which can generate strong magnetic fields that could damage electronics on earth. However, although we have satellites and telescopes that look at the signs of a CME, we cannot predict with precision which ejections represent a threat, because it depends on the magnetic field inside the CME themselves.

Among our most reliable tools to measure these magnetic fields are satellites in stable gravitational orbits around the earth called Lagrange points. These satellites are located hundreds of thousands of kilometers from the earth – but they are still positioned only about 1% of the distance between our planet and the sun, which helps to explain why they can only give the power of the power of a CME less than an hour before it strikes.

Now, Emma Davies at the Austrian Métée Office of Graz and her colleagues found a way to provide a previous warning using the solar orbiter of the European Space Agency, which orbit our star between 30 and 90% of the distance between the sun and the earth. “Solar Orbiter is a scientific mission, it is not really designed for this purpose,” explains Davies. “It is only a bonus that we were able to use it for a fortuitous alignment when a CME arrives.”

On March 17 and 23 of this year, Solar Orbiter passed between the earth and the sun when two pairs of CME began to run to our planet. Davies and his team used the measurements of the magnetic field spatial machine and the speed of the solar wind to model the internal magnetic structures of each CME, which they could then use to predict the force of the geomagnetic storm that each CME would produce. The entire process took less than 5 minutes and allowed researchers to predict the strength of storms 7 and 15 hours, respectively, before reaching the earth.

The predictions corresponded closely to the geomagnetic forces of the real storm, explains Davies. This is actually surprising, she says, given the change that the magnetic field of a CME can feel when it moves to the earth. “The fact that not too much more happened to this was quite lucky, and these CMEs apparently behaved well,” explains Davies.

Future storms may not be so predictable, she warns, and it was always difficult to predict exactly when they arrived, with at least several hours of uncertainty for both.

Despite this, measuring the CMEs shortly after leaving the sun is an interesting activity, explains Chris Scott at the University of Reading, in the United Kingdom, which was not involved in the study. “This gives us an early warning as to the likely configuration of the magnetic field in each eruption,” he says, which can help us predict the power of a solar storm.

However, the data of two events will not be sufficient to refine the predictive models and many other observations will be necessary before we can have tailor -made solar storm monitoring missions that orbit near the sun, explains Scott.

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