NASA To Probe Atmospheric Substorms

A rocket lifts off from Cape Canaveral, Fla., with five satellites to study geomagnetic substorms. (By Peter Cosgrove -- Associated Press)

CAPE CANAVERAL, Feb. 17 -- Five science satellites on a single rocket blasted off into a golden sunset Saturday on a mission to try to figure out the source of powerful geomagnetic substorms in the Earth's atmosphere.

Scientists hope the $200 million Themis mission unravels the mystery behind the storms, which can damage communications satellites, disable power grids and shoot high levels of radiation on spacewalking astronauts and on airplane passengers flying over northern latitudes.

Scientists believe the storms also periodically intensify the spectacular light shows of the northern lights, or aurora borealis.

"For 30 years, people have tried to understand what causes the onset of these substorms," said Vassilis Angelopoulos of the University of California at Berkeley, principal investigator for the Themis mission. "Finding out the origin . . . has been so elusive."

NASA has never before launched so many probes on a single rocket. Last year a joint venture of Taiwan and the U.S. National Science Foundation launched six weather microsatellites on one rocket.

Little more than an hour after blast off, the first of the five probes separated from a Delta II rocket followed three seconds later by the four other probes. About two hours after launch, scientists at a Berkeley ground station initiated signals with each probe, officials said.

Each satellite will magnetically map North America every four days for about 15 to 20 hours in tandem with 20 ground stations.

"Everything went picture-perfect," said NASA spokeswoman Jessica Rye.

Scientists plan to begin receiving data from the probes in about two months and to continue receiving information for many years, officials said.

Scientists plan to begin receiving data from the probes in about two months and continue receiving information for many years, officials said.

The mission, if successful, will end the debate among scientists as to how the substorms are triggered.