The five dishwasher-size probes, to be launched on February 15, will be looking for the places where substorms start.
The mission, dubbed Time History of Events and Macroscale Interactions during Substorms (THEMIS), marks the largest number of scientific satellites NASA has ever launched into orbit aboard a single rocket.
"Substorms start from a single point in space and within minutes progress past the moon's orbit, which is why we need multiple satellites," Angelopoulos said. "A single satellite cannot pinpoint the location."
The probes will orbit for about ten months before they assume their desired position in an arc over North America (see image at left).
From there the probes will map the continent's magnetic fields every four days. Angelopoulos expects that the orbiters will observe more than 30 substorms during the two-year mission.
"By taking the knowledge we gain from this discipline, we can develop the ability to both monitor and eventually forecast the effects of space weather throughout the solar system," said Jim Slavin, director of the Goddard Space Flight Center's heliophysics division in Greenbelt, Maryland.
Predicting space weather is important for keeping spacecraft and astronauts safe during a strong magnetic storm.
(Related news: "Space Weather Could Scrub Manned Mars Mission" [August 9, 2005].)
Accurate predictions could also help prevent disruption of communications and avoid power-line transmission failures on Earth's surface.
Studying space weather "has become more and more important," Angelopoulos said, "due to our increasing reliance on sophisticated space systems."
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