Mission to the sun
June 28, 2013
NASA launched the Interface Region Imaging Spectrograph, IRIS, on a mission to find out how the sun heats its atmosphere to millions of degrees.
At its core, the sun melds hydrogen atoms into helium. Temperatures cool as energy travels outward through the layers. But then, in the lower atmosphere, known as the chromosphere, temperatures heat up again and peak in the sun's outer atmosphere, the corona reaching almost 3 million degrees Celsius (5.4 million degrees Fahrenheit).
Scientists hope that IRIS will help them understand why that is. They want to learn more about how this mysterious region drives solar wind, which is a stream of charged particles spewing from the sun.
"Every time we look at the sun in more detail, it opens up a new window for us," said Jeffrey Newmark, IRIS program scientist at NASA headquarters in Washington, DC.
This could help to better predict space weather that can disrupt communications signals on Earth. Solar activity directly impacts Earth's climate, and solar storms can knock out power grids, disrupt radio signals, and interfere with communications, navigation and other satellites in orbit.
IRIS is designed to capture detailed images of light moving from the sun's surface, known as the photosphere, into the chromosphere, as well as related data about conditions.
IRIS is 1.2 meters long (4 feet) and weighs just over 200 kilograms (440 pounds). It will be watching the sun from a distance of about 640 kilometers (400 miles) above Earth. It rode into orbit on a Pegasus rocket which was in turn dropped from an airplane that took off around sunset from the Vandenberg Air Force Base on California's central coast.
IRIS is designed to last for two years.
rg/mkg (Reuters, AP)