A Pegasus rocket is dropped from an aircraft off the Southern California coast, carrying a sun-observing satellite into space. The IRIS satellite will provide imagery that might help scientists better understand what goes on between the sun's surface at its extremely hot outer atmosphere.
NASA launched a satellite Thursday evening from off the California coast to find out how the sun generates the kind of intense energy that produces heat measured in millions of degrees as it moves away from the sun's surface.
Video: IRIS Launch Animation
IRIS, the Interface Region Imaging Spectrograph that might help scientists solve the solar mystery, was aboard a Pegasus XL rocket that was carried on a Lockheed L-1011 aircraft Thursday evening from Vandenberg Air Force Base, northwest of Santa Barbara. The aircraft soared over the Pacific to 39,000 feet before releasing the rocket and 7-foot-long satellite spacecraft into space.
The launch, originally scheduled for Wednesday, was rescheduled because of an electrical power issue at the base.
IRIS is tasked with providing information that will help researchers better understand what goes on between the sun's surface at its corona -- the glowing halo surrounding the sun that appears as a white ring during eclipses. Temperatures heat up from 6,000 degrees kelvin (about 10,340 Fahrenheit) -- to millions of degrees by the time that energy reaches the outer atmosphere.
The mysterious "interface region" in bewteen is where most of the sun's ultraviolet emission that affects Earth is generated.
The two-year, $182-million mission might help scientists understand solar wind, space weather, coronal mass ejections and solar flares, and how they affect Earth -- especially, communications equipment -- and spacecraft.
"IRIS will show the solar chromosphere in more detail than has ever been observed before," said Adrian Daw, deputy project scientist. "My opinion is that we are bound to see something we didn't expect to see.
"I think the biggest surprise will come once the mission is launched and it starts to observe the sun. We know to some extent what we hope to learn, what specific science questions we are going to answer, but there's always that element of surprise."
Whatever they see will be courtesy of the tiny IRIS satellite's ultraviolet telescope, capable of providing what could be stunning images, similar to those provided by the Hinode satellite (pictured, right), by discerning features as small as 150 miles across the face of the sun.
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