The Impact of Flares
Flares can be like gremlins to us Earth-dwellers. The highly-energetic protons and electrons expand the ionosphere, thus disrupting long distance radio signals. Our LEO satellites can have their orbits changed because of the expansion of the atmosphere and the resulting drag. Among these are the ISS. During sunspot maximums, when flares are most prevalent, the ISS loses 400 meters of altitude per day. During spot minimums it loses only 80 meters a day (the Shuttle boosts it back to altitude on each visit).
But that’s not the worst flares can do to our satellites. The high energy particles can disrupt or even destroy their sensitive circuitry. Many satellites have had their performance severely degraded by flares.
Flares can even shut down power grids. On Aug. 14, 2003, a large solar flare erupted. Shortly thereafter a large part of southern New Jersey was blacked out due to a blown transformer. The transformer blew because of currents generated in it by the flare.
Flares even affect airline routes. United Airlines, which flies many routes over the poles, reroutes flights during solar flares because aa flare can give passengers and crew the equivalent of a chest x-ray dose of radiation. They pose a particular danger to astronauts. Had astronauts been on their way to the moon during the '03 flare, they would have received a potentially fatal radiation dose.
The solar flare cycle generally follows the sunspot cycle, hitting a maximum every 11 years. But major flares have occurred during spot minimums.