NASA - National Aeronautics and Space Administration

The International Space Station taken from Space Shuttle Discovery as the Sun rises from behind Earth. The STS-119 and Expedition 18 crew took this picture after leaving the Space Station in March 2009. (NASA/ESA)
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SOLAR consists of three complementary instruments: SOVIM (SOlar Variable and Irradiance Monitor) covers the near-ultraviolet, visible and thermal-infrared regions of the spectrum; SOL-ACES (SOLar Auto-Calibrating Extreme UV/UV Spectrophotometers) measures the extreme ultraviolet; and SOLSPEC (SOLar SPECtral Irradiance measurements) covers the 180–3000 nm wavelength range. (ESA)
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The Belgian User Support and Operations Centre is part of the ground segment for the International Space Station. It is open 24 hours a day to make sure in-orbit payloads operate as planned, provide astronaut training and process scientific data received from the experiments. It is located in Uccle, Belgium on the premises of the Belgian Institute for Space Aeronomy. (BUSOC)
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SOLAR installed on ESA's Columbus laboratory on the International Space Station. SOLAR consists of three complementary instruments: SOVIM (SOlar Variable and Irradiance Monitor) covers the near-ultraviolet, visible and thermal-infrared regions of the spectrum; SOL-ACES (SOLar Auto-Calibrating Extreme UV/UV Spectrophotometers) measures the extreme ultraviolet; and SOLSPEC (SOLar SPECtral Irradiance measurements) covers the 180–3000 nm wavelength range. (ESA/NASA)
View large image Recently the International Space Station turned itself to position the European Space Agency's SOLAR instrument for a better view of the sun. It was the first time the station changed attitude for scientific reasons alone.

"The European scientists requested this so they could increase science and bridge over the two solar cycles," said Julie Robinson, International Space Station Program scientist. "The International Space Station Program took a look at the request and we were glad that we could change attitude to support the scientists."

SOLAR has been monitoring our sun's output since it was installed on ESA's Columbus laboratory module in February 2008. The package will celebrate its fifth anniversary next year.

"That is quite an achievement," says Nadia This, operations engineer at the Belgian User Support and Operations Centre, which controls SOLAR. "The instrument was designed to work for only 18 months."

SOLAR needs to be in direct view of the sun to take measurements but the space station's normal orbit obscures the view for two weeks every month.

"We want to record a complete rotation of the sun and that takes around 25 days," explains This.

The solution is to rotate the whole station, but moving the almost 925,000-pound orbital outpost -- the size of a typical block of apartments -- is not a simple undertaking.

Aside from calculating the correct orbit to keep SOLAR in view of the sun, other factors need to be taken into account such as ensuring the solar panels that power the station are not left in the dark.

Communication antennas need to be reoriented to stay in contact with Earth and other scientific experiments must be adjusted.

High-level discussions with all five space station partners were needed before the go-ahead was given.

SOLAR started recording a full rotation of the Sun on Nov. 19. On Dec. 1 the station spent two hours turning about 7 degrees so that observations could continue. It held this angle for 10 days before returning to its original attitude. As usual, the Belgian center will be following SOLAR's progress 24 hours a day.

SOLAR's observations are improving our understanding of the sun and allowing scientists to create accurate computer models to predict its behavior. The more accurate data we acquire, the more we will understand our nearest star's influence on Earth.

Recently, the 11-year solar cycle has shown irregularities, and the next maximum is expected in 2013, so SOLAR's spectral readings are of particular interest to scientists.

This original story was written and published by the European Space Agency on Nov. 28, 2012.