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all right welcome aboard the

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International Space Station

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I'm astronaut Ricki Arnold and I'm

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currently at one of our human research

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facilities on ISS where you can see

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centrifuges laptops and other scientific

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equipment across from me is another one

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ease experiment racks where you can see

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ultrasound imaging more laptops cameras

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other equipment all stuff that requires

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electrical power in fact we have so much

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equipment for science and life support

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that our electrical system has about

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eight miles or 13 kilometers of wiring

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to make it all work so where does this

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energy come from let's have a look from

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here in the cupola and through other

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windows you can easily see the solar

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rays soaking in the sunlight they are

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massive these four solar arrays are made

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of solar cell which are purified chunks

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of the element silicon together the

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solar arrays contain a total of 260

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2,400 solar cells and cover an area of

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about 27,000 square feet more than half

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the area of a football field that's huge

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when the station is in sunlight the

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solar arrays produce about 60 percent

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more power than we actually need during

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the daytime that extra power goes

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directly to charging our lithium-ion

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batteries now those batteries are

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essential because they provide the power

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we need during the 16 night times we

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have per day here on the space station

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the energy our solar arrays can produce

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is enough to power 40 homes and we can

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maximize the power we generate by

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rotating their arrays and two axes one

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like a windmill to track the Sun through

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the course of the day the other the

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track the sun's inclination or its angle

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in the sky

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the space stations electrical power

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system uses direct current to provide

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energy for our laptops lights water

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recovery system and science experiments

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thanks for coming aboard today now back

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to earth