Science NASA to visit “living, breathing star for the first time” | NASA to visit “living, breathing star for the first time” |
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| by William Atkins | |
| Thursday, 12 June 2008 | |
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Page 2 of 3 During the mission NASA foresees Solar Probe+ getting as close to the Sun as 4.4 million miles (7 million kilometers). (We are about 94 million miles [150 million kilometers] away from the Sun.) At such a close distance to the Sun, the spacecraft must withstand temperatures in excess of 2600 degrees Fahrenheit (1400 degrees Celsius) and radiation levels never experienced before by any other spacecraft. To do so it will contain a carbon composite heat shield. Not surprising, Solar Probe+ will be solar powered. It will produce electricity from liquid-cooled solar panels that will be able to expand and retract. Even these solar panels can't withstand such extreme conditions, and must be retracted at certain times. During its mission, scientists back on Earth hope to learn two important things they don’t currently know about the Sun: 1. The corona of the Sun is about 10800 degrees Fahrenheit (6000 degrees Celsius) in average temperature. As you get further away from the Sun, the temperature “should” decrease. It doesn’t. Instead, it increases. Scientists want to know “why.” 2. The solar wind whips past the Earth and other objects in our solar system at speeds of millions of miles per hour. However, at the Sun there is no particular direction of the wind—it's chaotic. Somehow, from the time these supercharged particles, which make up the solar wind, leaves the Sun to the time they reach Mercury, Venus, Earth, and the other bodies of the solar system, the solar wind begins moving in one direction. How this happens, when it happens, is all a mystery to astrophysicists. They want to know the answer to these questions.
Guhathakurta states, "To solve these mysteries, Solar Probe+ will actually enter the corona. That's where the action is." To unravel these questions and make some sense of them, Solar Probe + will contain a payload that includes many important sensing instruments. It will contain a magnetometer, a plasma wave sensor, a dust detector, electron and analyzers, and other such devices.
The spacecraft will also include the Hemispheric Imager (HI), a telescope that takes three-dimensional images of the corona. It uses a technique called coronal tomography. NASA calls it a "fundamentally new approach to solar imaging and is only possible because the photography is performed from a moving platform close to the sun, flying through coronal clouds and streamers and imaging them as it flies by and through them." |
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