The National Ocean and Atmospheric Administration (NOAA) has warned that the electrical grid of the United States is vulnerable to the effects of a major solar radiation storm. Widespread loss of communications or electricity is likely, and could even be life-threatening. An airline disaster caused by faulty communications and electrical blackout could easily kill over a thousand people.
How a radiation storm disrupts communications and satellites
In normal solar weather, most solar microwaves and shortwave radio waves are absorbed in the Earth's stratosphere. All long wave radio waves bounce off the ionosphere. All solar X-rays are blocked by the highest parts of the Earth's atmosphere. Charged particles from the solar wind are caught and deflected by the Earth's magnetic field.
During high intensity solar flares, so much solar radiation is released that the ionosphere itself is affected. This can disrupt radar and other radio transmissions, which rely on ionosphere reflection for long-distance communication. Even radio communications which are not lost in the ionosphere may be snowed under by the deluge of radio waves from the sun.
During a strong coronal mass ejection (CME), the charged particles of the solar wind may compress the "windward" side of Earth's magnetic field to the point that geosynchronous satellites are no longer protected by it. Uneven bombardment of ions can cause differential charges and arcing, which can damage communications and GPS satellites. Because of the expansion of the atmosphere when heated by increased radiation, Low-Earth Orbit satellites experience greater atmospheric friction and may fall out of orbit faster than expected.
Satellites which pass through the South Atlantic Anomaly, the place on Earth where the Van Allen radiation belts come nearest the surface, are especially vulnerable. Just passing through the region crashed laptops on board the Space Shuttle.
Charged particles travel much more slowly than electromagnetic radiation, so astronauts on board the International Space Station have enough time to take cover in a shielded area after a CME has been observed. Even so, an astronaut doing extra-vehicular activity can have no warning and no shelter from any increase in solar X-rays if the Earth's atmosphere is compressed too much.
Major solar events can also affect high altitude flights. The most common effects are slightly increased solar radiation levels and loss of both satellite and radio communications, especially for aircraft on great circle routes which take them near the North Magnetic Pole. These flights are usually rerouted during a major radiation storm.
During radiation storms, the associated auroral current can be strong enough to short out electrical grids and even cause fires. If there is widespread damage to transformers, extensive and prolonged blackouts will result. This will adversely affect every level and type of infrastructure, not just communication.
Cracks in the magnetic field
Cracks can occur whenever the magnetic field of the solar wind is opposite the magnetic field of the Earth. These cracks have been detected since 1979, although they were predicted much earlier. These cracks can be the size of California or even larger. Some cracks remain open for hours at a time.
The effects of these cracks are felt mostly in the Earth's ionosphere. Usually the only noticeable effect is a localized aurora, but cracks which occur during an intense radiation storm could magnify radio disruptions.
Radiation storms in history
The strongest confirmed solar storm in human history occurred on September 1 and 2, 1859. It started with a solar flare which was so intense that the amount of sunlight briefly doubled. When the solar particles from the flare reached Earth, they were in opposite alignment with the Earth's magnetic field and were strong enough to overwhelm it. Auroras were visible as far south as Hawaii, with the New York Times reporting that in Boston, the aurora was "so brilliant that about one o'clock ordinary print could be read by [its] light."
The auroral current was strong enough to short out most telegraph wires and even cause fires. Some telegraph operators were even able to cut off their battery power and communicate using only the geomagnetically induced current.
The radiation storm of 1989 was much less powerful, but it still caused the Hydro-Quebec power grid in Canada to go down for over 9 hours. A 1994 solar storm damaged 2 communications satellites and disrupted communications across Canada. The strongest effects of any solar storm are usually felt in Canada because it is the country which currently contains the North Magnetic Pole. Effects in Canada are also further aggravated because isolated northern communities are highly dependent upon satellite communication.
The current solar cycle will continue to be on the upswing through 2013. Even during solar minimums, a strong solar storm is always possible. To make matters worse, the electrical grid in the United States is 10 times as large as it was just 50 years ago. As a result, Earth communications are more vulnerable to radiation storms than ever before.