COSMIC STORMS COMING

By J. Madeleine Nash/Chicago

For nearly five years the Canadian communications satellite known as Anik E-1 circled the earth without a serious hitch. Last spring, though, the $220 million spacecraft faltered. For hours, until users could switch over to backup systems, the transmission of all sorts of critical data--credit-card transactions, newspaper layouts, electronic paging requests, television and radio broadcasts--stopped. It took scientists a while, but they finally figured out what had caused the outage: storm damage.

Bad weather in outer space? No doubt about it. Experts think a spark shorted out the connections between the satellite's solar-power panels and several dozen of its radio relays. The spark, in turn, was caused by an electromagnetic storm triggered when a blast of solar gas slammed into the earth's magnetic field at supersonic speed.

To the satellite industry, glitches like this are as familiar as they are vexing. But engineers and scientists are concerned about the potential for more serious problems. Just last month, at a conference at Montana State University, scientists warned that storms in space--like hurricanes and earthquakes--could have a devastating impact on society. Among other things, a large storm could totally disrupt communications over large swaths of the planet and cause power outages capable of paralyzing major urban centers.

The need to understand these so-called geomagnetic storms is an unanticipated consequence of the electronics breakthroughs of the past half-century. As a result, space meteorology lags far behind its terrestrial counterpart. But now, thanks to a new generation of satellites--including one, the Fast Auroral Snapshot Explorer, that was launched two weeks ago--scientists are getting unprecedented insights into both the electromagnetic weather patterns that affect the earth and the solar dynamo that powers them.

Already one of these new satellites, the Solar and Heliospheric Observatory, or SOHO, has taken movies of hot gas streaming into space from a magnetic belt girdling the sun. And the Polar Satellite, so-called because it passes over the North Pole, recently snapped the clearest pictures ever seen of the aurora borealis, the shimmering curtains of light that are the visible fallout from space storms.

What's most surprising, observes Joe Gurman, a space physicist at NASA Goddard Space Flight Center, is that all this is occurring despite the fact that we're currently in a solar minimum--the interval of relative calm that reigns between the end of one 11-year sunspot cycle and the beginning of another. Sunspots always signal more violent solar activity than average. But, says Gurman: "We now know that there's no such thing as a quiet sun."

What drives space weather is the solar wind, a never-ending gush of magnetized gas spewed out by the corona, the sun's glowing outer shell. This gas is so hot (two million degrees Fahrenheit) that atoms of hydrogen and helium are homogenized into a dilute plasma, composed mainly of negatively charged electrons and positively charged protons. Yet the solar wind is a gossamer thing, far less substantial than a whisper. "What you have," marvels Gurman, "is a million tons of matter moving at a million miles per hour. But its density is so low that essentially you're dealing with the physics of a vacuum."

As the solar wind races toward the edges of the solar system, it smashes into the magnetosphere, a long, teardrop-shaped region of space that marks the boundaries of the earth's magnetic field. The magnetosphere protects the earth by deflecting most of the solar wind around the planet the way a windshield deflects air around a car. Still, untold trillions of charged particles manage to leak through. Some are trapped to form the Van Allen radiation belts that surround the earth. Others spiral down the magnetic field lines that project from the North and South poles. Energy unleashed by this disturbance excites atoms of nitrogen and oxygen, which in turn emit pulses of colored light. The result: an aurora.

The leakage is greatest during geomagnetic storms, which happen when the sun turbocharges the solar wind by spewing out giant blobs of plasma. Ejected at extremely high speeds, they push particles through the magnetosphere with an unusual amount of oomph. During solar minimum, the biggest blobs come from openings in the sun's magnetic field called coronal holes. "Gas spews out of these holes," explains University of Colorado space physicist Daniel Baker, "like water from a fire hose's nozzle." If the nozzle is aimed toward earth, the consequences can be dramatic. Plasma from coronal holes may well have triggered the geomagnetic storms that crippled the Anik E-1 satellite and temporarily disabled at least six others.

The danger of geomagnetic storms is even worse, however, during solar maximum. At that time, long tongues of fiery plasma leap from the surface of the sun and rush toward earth like guided missiles. Sometimes the force of their impact is so great that the magnetosphere convulsively contracts. Even spacecraft in near-earth orbit can find themselves outside the magnetosphere's protective embrace, exposed to blasts of high-energy protons. A direct hit by these protons, experts warn, could prove lethal to astronauts working in space.

The most violent space storms of all occur when magnetic field lines in the solar wind connect with those that surround the earth, creating a kind of funnel that channels huge quantities of solar plasma into the magnetosphere. In response, powerful currents surge through the high reaches of the atmosphere, where they can utterly scramble broadcast signals, and even through seawater and bedrock. These surface currents can corrode buried pipelines, interrupt transatlantic phone conversations and overheat electrical transformers. In 1989, during the most recent solar maximum, currents induced by a geomagnetic storm brought down the power grid that supplies Canada's Quebec province.

The next solar maximum, due sometime around the year 2000, could create worse nightmares. For one thing, modern societies, with their cellular phones and satellite navigation and communications systems, have become more vulnerable than ever to electronic disruptions. Equally worrisome is the fact that electrical utilities have created enormous, interconnected power grids in an attempt to save money. The power outages that plagued the American West this summer provide a dramatic illustration of how vulnerable these systems have become. "The scale," says transmission expert John Kappenman of Minnesota Power and Light, "is scary." Financial losses alone would amount to billions of dollars, and if the blackouts occurred during a cold snap, or a heat wave, there could be a human toll as well.

With just a little warning, though, the people who manage satellites, pipelines and electric utilities might be able to limit damage by powering down damage-prone electronics or temporarily severing the connections among power grids. But first scientists must figure out how to make more accurate forecasts of the complex interaction between the solar wind and the earth.

The new satellites may help, but unfortunately SOHO and the Polar are research satellites, meaning that they do not transmit data continuously. But next year NASA will launch the Advanced Composition Explorer, or ACE satellite, and place it in permanent orbit between the earth and the sun. Moment by moment, ACE will sample the solar wind and, almost as quickly, relay its findings back. If a blob of plasma heads this way, then ACE will see it--and alert forecasters like Hildner that a big one is about to hit.