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Solar Dynamics Observatory gives us a deeper look at the Sun by Matt Ford
Friday, April 30th 2010, 6:39 AM EDT
Co2sceptic (Site Admin)
Image AttachmentFirst light: A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. False colors trace different gas temperatures.
Image source and click to read more from NASA/Goddard/SDO AIA Team - NASA's New Eye on the Sun Delivers Stunning First Images

Tomorrow's weather can be determined (over)simply by looking at what the weather's like wherever the wind is blowing from. Figuring out what the weather will be in space follows the same basic principle: look at what the Sun is doing now, and you'll get a sense of what will happen to the Earth in the near future.

Predicting what the Sun is doing or is going to do, however, is a much more complicated problem than standard terrestrial weather prediction. I have heard it said that the space weather prediction capabilities of today are about 30 to 40 years behind the capabilities of the weather forecast on the local news. To help us understand space weather and climate, NASA recently launched the Solar Dynamics Observatory (SDO).

The Sun is an incredibly complex physical environment, one where gravity, pressure, fusion reactions, plasma physics, and multiple complicated magnetic fields come together to form a highly dynamic system. A system that, in a fraction of a second, can burp off an arc of material greater than the entire mass of Earth. To study it, the SDO has been placed in a geosyncronous orbit above a dedicated ground receiving station in New Mexico. Its trio of instruments are capable of taking images of the Sun with a resolution 10 times that of an HDTV, streaming over 1GB of data down to Earth every minute.


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The main scientific goals of the SDO focus on how and why the Sun's magnetic field changes, how energy is stored in the magnetic field, and, ultimately, how it is released into geospace. With an understanding of the physical dynamics of the Sun itself, the information can be used to more accurately predict space weather. Those predictions have big implications for the equipment that we have parked up there, and for the representatives of humanity who temporarily reside in space.

According to NASA, there are seven specific scientific questions that the SDO Project seeks to answer:

1. What drives the 11-year cycle of solar activity?

2. How is magnetic flux created and transported across the solar surface?

3. How does the breaking and reconnection of magnetic field lines affect the overall magnetic field and affect the outer reaches of the solar atmosphere?

4. Where do variations in the Sun's extreme ultraviolet brightness come from and are they linked to the magnetic field?

5. What magnetic field events lead to coronal mass ejections?

6. Can the solar wind that reaches Earth be predicted based on the magnetic field and near the Sun's atmosphere?

7. When will activity occur, and is it possible to make accurate and reliable forecasts of space weather and climate?

The SDO has three primary instruments for carrying out its science mission. The Helioseismic and Magnetic Imager (HMI) will primarily be used to try to track internal solar processes by studying what goes on at the surface of the Sun. Unlike the Earth, which has a relatively easy-to-describe magnetic field, the sun has countless magnetic fields that help drive solar flares, sunquakes, and a wide variety of other solar phenomena.

HMI's job will be to monitor the magnetic fields found on the surface of the Sun. It is hoped that a more detailed understanding of the magnetic fields on the surface will provide clues into the inner workings of the star.

Next up is the Atmospheric Imaging Assembly (AIA). Its primary role will be to image the solar corona—the outer layer of the Sun's atmosphere. Within the corona itself, temperatures can range from a relatively cool 20,000K to a scorching 20,000,000K.

The instrument will be capable of following solar mass ejections from their origin as microinstabilities where surface magnetic fields reconfigure, and track them as they grow into the largest explosions in the solar system. Mass ejections can send millions of tons of charged material streaming out into the solar system and, when they end up pointed at Earth, they cause what we experience as a solar storm. The four telescopes that make up AIA will provide eight full-Sun images every ten seconds, twenty-four hours a day, seven days a week.

Last up is EVE, the Extreme ultraviolet Variability Experiment. The Earth's upper atmosphere completely protects us from the effects of EUVs, but also prevent us from measuring light at these wavelengths from the surface of the planet. Solar scientists and space weather researchers are interested in why the brightness of EUVs changes when the magnetic fields of the Sun change. Measurements from EVE will be used to help space weather observers know when a burst of EUVs are headed towards a satellite or astronaut stuck outside the protection of a spacecraft.

The SDO has a planned mission life of five years. Hopefully, with the data gained from this mission, space weather prediction will become more modern and robust, where a solid understanding of the dynamical processes that create weather allow us to known when and how it will affect us.

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Source Link: arstechnica.com
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