The satellite was boosted on a Pegasus XL rocket, dropped Wednesday from an L-1011 jet flying at 39,000 feet over the Pacific Ocean off the California coast, said NASA spokesman Jim Sahli.
"Everything is working well," Sahli said about 90 minutes after the evening launch. The satellite was in an orbit ranging in altitude from 324 nautical miles to 352 nautical miles.
The 469-pound Transition Region and Coronal Explorer satellite (TRACE) will observe the sun for a year. Its goal is to study the connection between the sun's magnetic fields and the heating of its corona.
Scientists want to know more about solar events that have the potential to threaten astronauts and disrupt use of orbiting satellites that have such critical functions as communications, navigation, weather forecasting, and national security.
Periods of intense solar activity - massive flarings and huge eruptions - will occur in the coming months of the sun's cycle. The big events are interspersed with periods of relative quiet. TRACE is intended to study the complete range of solar conditions.
The satellite was developed by the National Aeronautics and Space Administration's Small Explorer Program, intended for highly focused science missions.
The Pegasus XL is a winged rocket built by Orbital Sciences Corp. The rocket drops for five seconds before the first of three stages ignites.
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