October 6, 2012
NASA SDO Team Overcoming Eclipse-Related Image Quality Degradation
redOrbit Staff & Wire Reports — Your Universe Online
A NASA satellite studying the sun saw its view obstructed by Earth for a brief period of time each day throughout much of the month of September. Those eclipses had an unusual effect on the images captured by the probe immediately afterwards, the U.S. space agency revealed on Friday.
NASA's Solar Dynamics Observatory (SDO) moved into what is known as its semi-annual eclipse phase from September 6 through September 29, officials from the organization explained. During each of those days, our planet temporarily obscured the satellite's view, with "a period of fuzzy imagery" following for a period of approximately 45 minutes afterwards.
"Scientists choose orbits for solar telescopes to minimize eclipses as much as possible, but they are a fact of life --- one that comes with a period of fuzzy imagery directly after the eclipse," NASA said. "The Helioseismic and Magnetic Imager (HMI) on SDO observes the sun through a glass window. The window can change shape in response to temperature changes, and does so dramatically and quickly when it doesn´t directly feel the sun´s heat."
“You´ve got a piece of glass looking at the sun, and then suddenly it isn´t,” Dean Pesnell, the project scientist for SDO at the Goddard Space Flight Center, added. “The glass gets colder and flexes. It becomes like a lens. It´s as if we put a set of eye glasses in front of the instrument, causing the observations to blur.”
In an attempt to counter that phenomenon, the HMI unit was fitted with special heaters that warm the windows during an eclipse. Ordinarily, with no adjustments to the heater, it took SDO roughly two hours to return to prime observation capabilities. Initially, with the heater, that time was reduced to 60 minutes, but in the two years since the satellite's 2010 launch, Pesnell and his colleagues have cut the waiting period for clear pictures down to 45-50 minutes.
SDO is studying the sun as the source of all space weather, which impacts our lives here on Earth, as well as the planet itself and everything located outside of its atmosphere, according to NASA's mission overview website.
It is the first satellite under the Living with a Star (LWS) program. It has also been designed to operate for five years and is capable of producing enough data to fill a single CD every 36 seconds, according to the U.S. space agency. The satellite is expected to enter its next eclipse season on March 3, 2013.