NASA satellite sent warning of magnetic storm cloud First readings of its kind doubted at first

scientists waited to give public alert

November 15, 1995|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

A NASA satellite patrolling interplanetary space 650,000 miles from Earth last month triggered the first warning the planet has ever had of an approaching magnetic storm cloud.

Scientists at the Goddard Space Flight Center initially doubted the new satellite's readings, however, and waited a day before LTC issuing a public alert, they said. The cloud of charged atomic particles, meanwhile, swept the Earth less than 30 minutes after the first warning, causing a surge on a Wisconsin power grid and two days of northern lights from Denver to Sweden.

Some magnetic storms also have the power to disrupt satellite communications and threaten astronauts, but no such effects were reported last month to Goddard.

"We said it was going to be not a large one, but a medium storm. And that was pretty much borne out by the observations," said Dr. Mario Acuna, project scientist with Goddard's solar-terrestrial physics program.

The magnetic cloud, created by an eruption on the surface of the sun, was detected by NASA's Wind spacecraft. Launched a year ago, Wind is en route to a spot 1 million miles from Earth, where it will watch for magnetic storms.

At 4 p.m. Oct. 18, Wind detected the cloud racing toward Earth at 2.1 million mph. Its power and other characteristics were relayed to Goddard, and from there to the U.S. Air Force and the federal Space Environment Laboratory in Colorado.

Satellite operators and utility managers would have had a half-hour to protect their systems from the barrage of charged particles carried by the cloud. But the "space weather alert" was delayed, Dr. Acuna said.

"The field was so strong and funny that people thought the [Wind] instruments were broken," he said. "We had to verify that they were all functioning, and that took a day."

Wind is scheduled to take up its final position next summer.

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