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Predicting Space Weather Becomes More Precise


Predicting space weather is getting more precise. Twice in the past week, forecasters have warned us about two solar storms with the potential for creating havoc among Earth's electrical systems and orbiting satellites. The world is much better prepared to deal with ferocious solar activity than it used to be.

At one time, scientists thought the space between Earth and Sun was a vacuum. But we now know that the sun fills it with gusts of hot, electrically charged atomic particles called the solar wind.

Sometimes this wind blows very hard, as it has with the two most recent solar flares. When the sun's outer layer, the corona, is very active, it hurls nearly one-third of its gaseous matter outward at supersonic speeds. A heavy blast can produce a shock wave that compresses our planet's magnetic field.

The U.S. government's oceans and atmosphere agency NOAA has a Space Environment Center that monitors these discharges. Center director Ernest Hildner says intense solar emissions are not dangerous to people on the ground, but can shut down satellites, power networks, communications, and other technical systems.

"When there are variations in the sun's output, when the sun has a storm, an eruption of plasma and magnetic field, it smacks the Earth's magnetic field and it causes difficulties to our technological systems," he said. "That is what we think of as space weather."

The intensity of these solar blasts varies over an 11-year cycle as the sun's magnetic field grows stronger, then weaker. The peak of the most recent 11-year solar cycle came in 2000, but is still a few years from the bottom.

"So we are anticipating a higher frequency of more severe space weather storms this period of time lasting a few years around the absolute maximum of the cycle," said Ernest Hildner.

Solar eruptions can do powerful damage. One in 1989 caused a nine-hour power blackout in Quebec, Canada. We have come to depend on technology more than ever in the ensuing years, but the difference between 1989 and now is that the world is better equipped to predict a solar flare on short notice.

Several U.S., European, and Japanese satellites have gone into orbit during the past decade to measure the sun and its emissions. One of them is at a point where it can warn us that solar particles are just one-hour away. Mr. Hildner says these orbiters have improved short-term space weather predictions.

"We are still not much better than we were on the one-day, two-day, three-day prediction, but on the one-hour prediction; we are much better than 90 percent correct now," he said.

This gives just enough time for Mr. Hildner's Space Environment Center to issue alerts so managers of vulnerable systems can take protective action, such as shutting off a satellite's power temporarily.

Crewmembers aboard the international space station take precautions, too, such as retreating to special areas shielded from this radiation. In addition, their sleeping bags are lined with a protective material made of high-density plastic called polyethylene.

An industry has emerged to advise businesses on how to prepare for solar flares. The Metatech Corporation is a firm that consults with electric power suppliers. Metatech executive John Kappenman says his company uses a solar storm forecast to predict how the blast will affect a power network and tell its managers where to regulate voltage to avoid an overwhelming surge.

"The good news is that we do have that capability now, an advance geomagnetic storm forecasting system," said John Kappenman. "It continuously updates the space environment conditions as well as impact conditions to the power grid on a minute-by-minute basis. It needs to be that fast because storm conditions are changing that rapidly."

But the satellite industry is less advanced in this regard. An engineer who advises it, David DesRocher of The Aerospace Corporation, says the industry must become more aware of the problem.

"We are not at all at the point right now where we could say this satellite will experience this effect," said David DesRocher. "We are trying to close in on that. It is a very complex problem. Every satellite is different. The way to get there is to open the eyes of industry to say there is an economic interest for it here to learn more about cause and effect."

The latest outbursts from the sun should be a good test of how well the improved space weather forecasts are minimizing solar storm damage.

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