Space weather, determined mainly by solar activity, rarely troubles us on Earth. We are not bothered if satellites are buffeted by solar winds, unless they stop working. However, extreme solar events may cause real problems down here. Giant, once-a-century solar storms are a known threat to power grids, but aircraft may be at risk from far more frequent events according to a new study of data from a neutron storm in February 1956.
There is a steady background drizzle of neutrons, but when a large solar flare strikes the Earth’s atmosphere it can produce a cloudburst of them. We are shielded from most of the neutrons by the atmosphere, but radiation is more intense the higher you go. During the event in 1956, monitors showed 50 times the base level of neutrons at sea level. Airliners at the time mainly flew below 20,000 feet and were at little risk.
Clive Dyer, of University of Surrey Space Centre, one of the report’s authors, says modern airliners, which cruise at twice the altitude of the earlier aircraft, would be exposed to 15 times as much radiation. A neutron storm like the event in 1956 would expose passengers to radiation equivalent to the annual working limit for air crews, and could also cause critical flight electronics to fail.
Such storms occur in clusters, and Dyer warns they can occur as often as seven times a century. A warning system could direct planes to fly at lower altitudes to avoid dangerous neutron showers.
