Features

SAN FRANCISCO — The $5.5 billion Iridium global telephone system couldn’t attract enough customers to keep the company out of bankruptcy court, but its network of 66-plus satellites is paying off for scientists. 

The 1,500-pound satellites are taking the most comprehensive global measurements ever of space weather, the interaction of the Earth’s magnetic field with charged particles that stream off the sun, scientists said Friday. 

“The Iridium system provides a marvelous opportunity for viewing space weather,” said Brian Anderson of the Johns Hopkins University Applied Physics Laboratory.  

“You essentially have a network of space weather stations.” 

Though the electrical currents that stream toward the Earth’s poles during space “storms” drive the Northern and Southern lights, they can damage spacecraft electronics, harm astronauts, knock out electrical grids and reduce the life span of satellites. 

Eventually, researchers believe they will have enough data to predict space weather and its effects – much as meteorologists on the ground better understand the paths and effects of storms by studying historical records. 

“Diagnosing the space environment is very important for predicting what effects will occur and when they will occur,” Anderson said at the annual fall meeting of the American Geophysical Union. 

Space storms have been difficult to understand, because no system was in place to constantly monitor global changes in electrical currents and magnetic fields.  

The 66 Iridium satellites and several spares swarm around the planet at an altitude of 470 miles in various polar orbits. 

Iridium, a multinational partnership led until this week by Motorola Corp., was built to provide global wireless telephone and pager service.  

Each satellite was equipped with a magnetometer, an instrument that helps keep the solar panels pointed at the sun. 

Scientists realized that the magnetometers also can be used to measure changes in Earth’s magnetic field. The data were combined with radar to create global maps of electric power flowing to the polar atmosphere. 

“For the first time, Iridium measurements enable us to track the location and the magnitude of electrical power coming into this vast region,” said Colin Waters of Australia’s University of Newcastle, New South Wales. 

The research was sponsored by the National Science Foundation. 

Though an accidental scientific success, Iridium flopped commercially. Though the phones and pagers worked from anywhere on the planet, the bulky handsets that cost $3,000 and stratospheric rates of up to $7 a minute alienated customers. 

Iridium LLC filed for bankruptcy protection in August 1999. Earlier this week, all the company’s assets, including the satellites, were sold for $25 million to a group of private investors who plan to offer service to government and industrial clients. 

It was not immediately clear whether the sale would affect the system’s secondary scientific mission, Waters said. Until recently, however, Motorola had planned to deorbit the satellites. 

Iridium, developed over 12 years, was originally to consist of 77 active satellites and named after the element with 77 electrons. Later, organizers realized they needed only 66 satellites but didn’t change the name to Dysprosium, which is Greek for “hard to get at.” 

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On the Net: 

National Science Foundation: http://www.nsf.gov 

Johns Hopkins Iridium information: http://sd-www.jhuapl.edu/constel—mag—science/