February 17, 2007
Five Science Satellites Blast Off on Rocket
By JIM ELLIS
CAPE CANAVERAL, Fla. - Five science satellites blasted off on a single rocket into a golden sunset Saturday on a mission to figure out the source of powerful geomagnetic substorms in the Earth's atmosphere.
The launch at 6:01 p.m. from the Cape Canaveral Air Force Station came a day after it was scrubbed Friday after strong upper winds forced officials to wait 24 hours, said Rani Gran, NASA spokeswoman.
Scientists hope the $200 million Themis mission unravels the mystery behind the storms that can damage communications satellites, disable power grids and shoot high levels of radiation down on spacewalking astronauts and airplane passengers flying over northern latitudes.
Scientists believe they also periodically intensify the spectacular light shows seen in 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, Berkeley, principal investigator for the Themis mission. "Finding out the origin ... has been so elusive."
It is the most probes NASA has ever launched on a single rocket. However, 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 University of California at 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 continue receiving information for many years, officials said.
The mission, if successful, will end the debate scientists hold as to when the substorms are triggered.
One theory holds that the substorms start about 50,000 miles above the Earth's equator, about a sixth of the way to the moon, when the electromagnetic turbulence disrupts the flow of intense space currents.
The other theory is that the substorms are triggered about 100,000 miles above the equator with the spontaneous conversion of magnetic energy into heat. Particle acceleration then triggers the substorm energy.
Associated Press writer Mike Schneider in Cape Canaveral contributed to this report.