It's a 550 million two-year mission.
CAPE CANAVERAL, Fla. (AP) -- Twin spacecraft blasted off Wednesday night on a mission to study huge eruptions from the sun that can damage satellites, disrupt electrical and communications systems on Earth and endanger spacewalking astronauts.
The two spacecraft, known as STEREO, for Solar Terrestrial Relations Observatory, lifted off, stacked one on top of the other, aboard a single Delta II rocket.
The liftoff was delayed by several minutes after launch managers became concerned late in the countdown that winds could blow toxic material over populated areas should there be an accidental explosion. However, the winds became acceptable about 15 minutes before launch, permitting the rocket to soar off the launch pad with a roar.
Scientists hope the 550 million two-year mission will help them understand why these eruptions occur, how they form and what path they take.
The eruptions -- called solar flares -- typically blow a billion tons of the sun's atmosphere into space at a speed of 1 million mph. The phenomenon is responsible for the Northern Lights, or aurora borealis, the luminous display of lights seen in the upper latitudes of the Northern Hemisphere.
"Of the bazillion stars that we have in our night sky, the sun is the only one that counts," said NASA scientist Madhulika Guhathakurta. "Any understanding or breakthrough we can make in understanding the sun's environment is of direct relevance to every human being on this planet."
The two observatories will provide scientists with the first-ever three-dimensional view of the sun by working in tandem, like a set of eyes, in different orbits.
NASA hopes information about the solar flares helps the astronauts who fly to moon and eventually Mars in the coming decades. Astronauts exposed to the eruptions can receive a year's worth of radiation.
The spacecraft's launch was delayed several times this year because of technical problems.
Scientists plan to release to the public movies and other images created by the STEREO spacecraft, though viewers may need to use the type of 3-D glasses worn for movies like "Creature From the Black Lagoon."
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