Two blankets of solar cells make up a solar array wing, or SAW. Each wing is 115 feet long by 38 feet wide. Each SAW weighs more than 2,400 pounds and uses 32,800 solar array cells. Image Credit: NASAHow do you get electricity 220 miles above Earth? No extension cord or power cable is available for that job. The best source of energy for spacecraft is sunlight. Engineers have developed technologies to convert solar energy to electrical power efficiently.
Two solar array wings make up a set of solar arrays. The two wings are deployed in opposite directions. The total wingspan is more than 240 feet, including equipment that connects the two halves and allows the SAW to turn toward the sun. Image Credit: NASAThe space station's solar arrays were installed over several space shuttle missions. When astronaut Bill McArthur was on the station, it had one set of solar array wings. McArthur was the commander of Expedition 12 from October 2005 through April 2006. In March 2009, the STS-119 space shuttle crew installed and deployed the fourth and final set of solar arrays.
The International Space Station has four sets of solar arrays. Image Credit: NASAOn Earth, the electricity that comes from power plants is called alternating current, or AC. In the United States, this means that the direction of the current, or flow, of electricity changes about 60 times per second. The alternating current is the best way for electricity to travel over long distances. On the station, the electricity does not have to travel as far. The solar arrays convert sunlight to direct current, or DC, power. DC flows in the same direction at all times.
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