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  sci-tech > space > story pagecorner  

Forget Y2K: Prepare for the solar maximum

Solar corona image
A coronal mass ejection is expelled from the sun in this image taken Saturday by the SOHO spacecraft  

September 1, 1999
Web posted at: 2:11 p.m. EDT (1811 GMT)

In this story:

'A billion tons of matter moving a million miles per hour'

Improved prediction would help


By Robin Lloyd
CNN Interactive Senior Writer

(CNN) -- A few days ago, a handful of satellites in space watched the sun spit up an unusually high-energy flux of X-rays followed by what could have been an Earth-menacing cloud of charged particles.

The solar flare fell into the most powerful category of electromagnetic radiation, and the burp that followed, called a coronal mass ejection, had the potential to disrupt power grids on Earth and kill astronauts

Luckily, it was pointed the wrong way and ended up just glancing the planet. No troubles were reported.

But the event portends the upcoming "solar maximum" -- a fickle wave of even more energetic solar flares and ejections that could disrupt radio communications for pilots, blow out transformers and power grids and deliver lethal radiation doses to humans in space.

"We are certainly at the part of the sun's cycle where flares are popping off more frequently and affecting us more frequently," said David Hathaway, a solar physicist at NASA's Marshall Space Flight Center in Alabama.

Solar maximums, about as predictable as a child's moods, occur about every 11 years. The next one will peak in mid-2000 and last for a year or two, Hathaway said.

Flares and ejections like the high-energy burst on Saturday are expected daily during the maximum. The question is, which ones will be aimed at Earth and which ones will pass by leaving the planet unperturbed? In the past few months, one or two ejections sped toward Earth but were too weak to cause any trouble.

The last solar maximums peaked in 1980 and 1990. The upcoming maximum could bring about far more damage and disruption at least in space because there simply is more stuff there to harm due to the recent boom in the commercial satellite industry.

NASA also has more satellites in orbit than ever before as it moves from big-budget missions to more frequent, smaller budget satellites and spacecraft with less ambitious objectives closer to Earth and the sun.

'A billion tons of matter moving a million miles per hour'

Saturday's solar flare was picked up by NOAA weather satellites and lasted just a few minutes.

The flares can cause problems, as they drop X-rays into Earth's atmosphere, changing its electrical field and the propagation of radio waves in it.

That means pilots of jets and other planes may be unable to reach the frequency they need for landing and other navigational information, said Ron Zwickl, assistant director for NOAA's Space Environment Center in Boulder.

The ejection associated with Saturday's flare had the potential to affect even more people had it been aimed at Earth, Hathaway said.

The coronal burp that followed the flare was observed by NASA's Solar and Heliospheric Observatory, or SOHO, satellite, orbiting around a gravitational balance point between the sun and Earth.

Ejections are composed mainly of ionized hydrogen gas but it's the weight and speed of the wave that makes it so dangerous. It takes a few days for such waves to reach Earth.

"One way to think of it is that it's a billion tons of matter moving at a million miles an hour," Hathaway said. "They are big beasts. For the sun, it's a small hiccup. But for the Earth it's a big event.

The ejections cause shifts in the Earth's magnetic field that can send surges through power lines than can take out transformers and circuit breakers. Ejections of that magnitude could occur once every two months on average during the maximum, Zwickl said.

With enough warning time, power companies can redistribute power to mitigate the surges and flight operators can try to turn satellites out of harm's way.

The trouble is that there is a third type of energy associated with flares and ejections that also can cause problems -- energetic waves of protons and alpha particles that follow about eight minutes after the flare. They reach Earth an hour or two later and can harm solar panels used to power satellites in space.

That leaves little warning time to prevent such events.

In some cases, all three energy waves reach Earth at once, backed up like a logjam and then pushed over the edge by the ejection, Zwickl said.

"When it hits, the worst can happen all at once. During the largest event, all of them can occur at the same time: radiation and geomagnetic activity," he said.

Improved prediction would help

Scientists hope to improve their ability to predict the energetic waves and coronal mass ejections because they can literally kill astronauts, especially those beyond Earth's atmosphere and heading toward the moon or Mars.

The ability to detect the flares and ejections is there, but scientists currently lack the ability to predict how damaging they will be.

"All you can say now is sort of like a storm coming in. You can tell them there's a storm coming but you can't predict all the effects of it. You just know the problems increase and the potential is there," Zwickl said.

Hathaway said he enjoys watching the sun do its thing as it approaches its maximum activity period.

"It's just a reminder that it isn't a boring object sitting in the middle of our solar system," he said, "but a very active beast that acts up occasionally."

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NASA's Marshall Space Flight Center
SOHO: The Solar and Heliospheric Observatory
NOAA's Space Environment Center
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