October 24, 2003
kmbc

Scientists say they are expecting a strong geomagnetic storm to hit Earth Friday -- and there could be some problems for electrical grids and satellite communications.

Forecasters at the National Oceanic and Atmospheric Administration in Boulder say they have watched one of the largest sunspot clusters in years develop over the last three days.

They say that produced what is called a coronal mass ejection -- and that's similar to a solar flare.

A coronal mass ejection is an explosion of gas and charged particles into space from the corona -- the outermost layer of the sun's atmosphere.

Solar storms can damage satellites, power grids and pipelines, as well as other electrical disturbances that can affect cable TV, pager and cellular telephone service.

Satellites in orbit high above the Earth's protective atmosphere are particularly susceptible to solar radiation. High-energy electrons from the storm can penetrate spacecraft, zapping the electronics and turning data bits from "0" to "1" or vice versa, causing the satellites to go into unexpected modes and maneuvers.

The list of major satellites knocked out by solar storms is long and costly. A recent example is the $200 million AT&T Telstar 401 satellite that experienced a massive power failure in 1997 only days after a solar storm arrived at Earth. Among networks affected were ABC, Fox and PBS, which used the satellite to beam programming to affiliate stations. The satellite also carried pager service, which was knocked out to 45 million people.

Three earlier-model satellites were also disabled in 1994 by a solar storm which triggered electrical failures in them.

The administration says a similar storm could happen again sometime over the next two weeks.