The Science of NASA's Newest Solar Explorer, IRIS
On June 27, 2013, NASA will launch the Interface Region Imaging Spectrograph (IRIS), which is its newest mission to study the sun. The IRIS investigation combines advanced numerical modeling with a high-resolution UV imaging spectrograph. IRIS will show the lowest levels of the sun's atmosphere - the interface region - in more detail than has even been observed before. This will help scientists understand how the energy coming through this area helps power the sun's million-degree upper atmosphere, the corona, as well as how this energy powers the solar wind constantly streaming off the sun to fill the entire solar system. The interface region is the greatest source of ultraviolet light that impacts the earth and the space around it.
Transcript
00:00:00 (music) Narrator: The secrets of the sun, are hidden in how energy travels up through its layers out into space. The sun's energy starts in its core; a giant fusion engine where hydrogen atoms are turned into helium atoms. The energy produced their moves up through the convection zone to the sun's surface, the photosphere. Moving magnetic fields contribute extra energy along the way. As energy moves outward, the temperature continually drops. This is just as one would expect, while moving away from a heat source.
00:00:41 Adrian Daw: Up until that point everything makes sense, in that the hottest part is in the middle, and everything gets gradually cooler as we move away. But then something very interesting starts to happen which is that it starts to get hotter again. Narrator: This layer, where the temperature mysteriously begins to rise again, is called the, chromosphere. It lies in an interface region between the photosphere and the corona the hottest and outer most region of the sun's atmosphere. Observations from the IRIS mission will help distinguish among numerous theories on how corona is powered. Adrian Daw: IRIS will show the solar chromosphere in more detail then has ever been seen before. It will be taking images
00:01:23 in spectra of specifically chosen wavelengths of ultra violet light and these will be the highest resolution, perhaps more importantly, a more rapid rate then has ever been done before. Narrator: The interphase region is the greatest source of ultra violet light that impacts the Earth and the space around it. Only a specifically designed spacecraft can image the wavelengths of light needed to study the chromosphere. Advance computer modeling will enable scientists to interpret the data, and better understand how the energy moves through the chromosphere. Adrian Daw: The light from the chromosphere is difficult to interpret because of the complicated interaction that the light has with the matter, bounces around if you will
00:02:04 many times before its final bounce, towards this. And this means that interaction between light and matter is to be modeled in great detail due to, not just advances in computational power of computers but, in the computational techniques that have been developed by the IRIS team. We are in a position to do this. Narrator: It takes only a small fraction of the chromospheres energy to power the corona. Adrian Daw: Although the corona is extremely hot, millions of degrees, it's at a low density, so it doesn't actually take a lot of energy to heat it to that temperature. The chromosphere on the other hand is a much higher density all be it,
00:02:46 lower temperature and there's much more energy deposited in the chromosphere in the corona. So that a tiny fraction of that energy in the chromosphere escaping into the corona is, is plenty to power all of the processes that we see from heating to such extreme temperatures, to driving the solar wind that fills the whole solar system; impacting all the planets, including our own. We hope to better understand these fascinating and important processes with IRIS. (beeping)
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