To protect Earth from the potentially devastating effects of extreme space weather, scientists have proposed the construction of a giant magnetic shield around the planet to deflect disruptive particles away from it.

Solar storms are caused by eruptions on the sun’s surface. Flares, sunspots and coronal mass ejections (CMEs) are often the cause of this activity, with these phenomenon all involving the sudden release of magnetic energy that is carried through space on solar winds. If the charged particles from these events hit Earth directly, they can disrupt satellite systems and power lines, leading to blackouts and communication system failures.

In September 1859, the largest solar storm ever recorded took place. A CME hit Earth’s magnetosphere, leading to the failure of telegraph systems across Europe and North America, with pylons throwing sparks. In 2008, the National Research Council estimated a similar size solar storm hitting Earth today would result in damage that would cost the U.S. around $2 trillion. Globally, this figure could reach $10 trillion.

In their study, which is yet to be published in a peer-reviewed journal, Manasvi Lingam and Abraham Loeb, from the Harvard-Smithsonian Center for Astrophysics, calculated the economic losses that could arise from future solar storms over time. Using a mathematical model and a number of assumptions relating to electricity generation and the growth of grids globally, they estimate the maximum economic damage will “grow exponentially” over the coming years until reaching a saturation point, where technological growth slows down.

“The vulnerable phase is during the relatively short-lived regime of exponential amplification that is likely to begin a few decades henceforth,” they wrote. “The ideal scenario entails the identification and implementation of an effective strategy to mitigate the risks from extreme space weather events within the next century.”

So how to protect Earth from large solar storms of the future? Lingam and Loeb say a huge magnetic shield surrounding the Earth that could deflect charged particles would be a possible solution. They say the shield would need to be placed a “certain distance” between Earth and the sun.

The scientists acknowledge the proposal is not exhaustive from an engineering point of view and say there will be challenges, including how to maintain a current to the magnetic shield. However, they say that from an economic point of view the shield makes sense, estimating the cost of a 105 ton shield to be around $100 billion. “This value is comparable to the total cost of the International Space Station,” the scientists say, “and is three to four orders of magnitude lower than the current world GDP, or the economic damage from a flare around 100 years henceforth.”

As well as the economic value, Lingam and Loeb say their plan also has implications for the search for extraterrestrial life. They say that any advanced alien civilization may have faced a similar problem as it developed technologically and potentially came up with the same solution of a giant space shield—and we could search for “technosignatures” around other stars and planets.

“It seems reasonable to conclude that technologically advanced civilizations on planets orbiting these stars would be well aware of the economic and biological risks posed by flares and superflares,” they said. “In order to mitigate the damage wrought by extreme space weather events, it is very conceivable that they would adopt shielding strategies against such phenomena.… [This would] necessitate large-scale engineering projects that may be detectable by future observations.”