IRIS aims to solve mysteries of the sun’s atmosphere

NASA launches a mission to learn about the sun.

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Science Recorder | Rick Docksai | Saturday, June 29, 2013

A newly launched NASA satellite is training its telescope on the sun to capture new data on the workings of the solar atmosphere. The Interface Region Imaging Spectrograph (IRIS), as the spacecraft is named, will use ultraviolet-enabled telescope and other on-board instruments to gather detailed images of the sun’s outer layers and, its designers hope, help answer some questions about the processes that the sun’s heat energy goes before leaving the surface and reaching Earth and the other planets.

The satellite lifted into space Wednesday, June 26, from the Vandenberg Air Force Base in California. The private space-flight company Orbital Sciences Corporation provided the rocket that launched the satellite into space.

Now space-borne, the satellite will carry out a two-year mission to examine the interactions between the sun’s surface and the corona, the hottest region of the sun’s atmosphere. A region called the chromospheres lies between these two zones, and NASA researchers say that IRIS’s instruments will show the chromosphere in greater detail than has ever before been seen.

They are also hoping that the mission will help explain the mysterious heat surge that solar particles undergo when they reach the chromosphere. According to NASA, the sun’s mass rises up from its core, the sun’s hottest zone, and gradually lowers in temperature as it nears the surface. Then its temperature spikes again as it travels through the photosphere to the corona and, eventually, out into space.

Astronomers agree that some unidentified process is conveying heat energy to the corona and, in turn, to the chromosphere. IRIS may help them figure out what it is.
Whatever is taking place in the corona and chromosphere, it makes a big difference for life on Earth. These interactions drive the solar wind and are responsible for most of the sun’s ultraviolet radiation. The solar wind impacts Earth’s atmosphere, creates the aurora borealis phenomenon, and occasionally interferes with radio transmissions here on our planet, while the ultraviolet energy is what makes Earth’s climate hospitable to life.

IRIS will orbit stay in orbit around Earth while viewing the sun through its telescopic lenses. A team at NASA’s Ames Research Center in Moffett Field, California, will control IRIS throughout its mission. The spacecraft will transmit its information to an Earth-based NASA supercomputer, which will use it to construct 3-D models.

The mission follows nine previous robotic missions that the world’s space agencies have launched into space to study the sun. Several have viewed the sun from Earth orbit, like IRIS, while others docked at a closer location to the sun called the LaGrange point. One 2006 mission, NASA’s Solar Terrestrial Relations Observatory (STEREO), traveled to the sun’s own vicinity to view ejections of matter from the corona up close.

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