WEBVTT - How do Voyager 1 and 2 transmit messages from far away?

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<v Speaker 1>Welcome to brain Stuff from how Stuff Works dot com

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<v Speaker 1>where smart Happens. Hi, I'm Marshall Brain with today's question,

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<v Speaker 1>how are the Voyager spacecraft able to transmit radio messages?

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<v Speaker 1>So far? The two Voyager spacecraft certainly have an amazing

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<v Speaker 1>track record. They were sent to photograph planets like Jupiter, Saturn,

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<v Speaker 1>and Neptune, and they've just kept on going towards the

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<v Speaker 1>outer edge of the Solar System. Voyager one is currently

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<v Speaker 1>over ten billion miles or about sixteen billion kilometers away

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<v Speaker 1>from Earth and it's still transmitting. It takes about fifteen

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<v Speaker 1>hours for the signal to travel from the spacecraft to Earth.

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<v Speaker 1>The Voyager spacecraft used twenty three watt radios. For comparison,

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<v Speaker 1>your cell phone typically has a three watt radio inside,

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<v Speaker 1>So in the grand scheme of things, the voice Woyager

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<v Speaker 1>radios aren't really that high power in terms of transmitters.

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<v Speaker 1>Big radio stations on Earth transmitted ten thousand watts or more,

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<v Speaker 1>and they still fade out fairly quickly. The key to

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<v Speaker 1>receiving the signals here on Earth is therefore not the

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<v Speaker 1>power of the radio, but a combination of three other things. First,

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<v Speaker 1>NASA is using extremely large antennas. Second, those antennas are

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<v Speaker 1>directional and they point right at each other. And third,

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<v Speaker 1>the radio frequencies used by Voyager don't have a lot

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<v Speaker 1>of man made interference on them. The antennas that the

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<v Speaker 1>Voyager spacecraft use are huge. You may have seen people

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<v Speaker 1>who have large satellite dish antennas in their yards. These

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<v Speaker 1>are typically two or three meters or six to ten

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<v Speaker 1>feet in diameter. The Voyager spacecraft has an antenna that

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<v Speaker 1>is three point seven meters or about fourteen feet in diameter,

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<v Speaker 1>and it transmits to a thirty four meter a hundred

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<v Speaker 1>feet or so antenna on Earth. The Voyager antenna and

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<v Speaker 1>the Earth antenna are pointed right at each other. When

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<v Speaker 1>you compare your phone stubby, little omnidirectional antenna to a

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<v Speaker 1>thirty four meter directional antenna, you can see the main

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<v Speaker 1>thing that makes a difference in getting signals back from Voyager.

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<v Speaker 1>The Voyager satellites are also transmitting in the eight giga

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<v Speaker 1>Hurts range, and there's not a lot of interference at

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<v Speaker 1>this frequency. Therefore, the antenna on Earth can use an

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<v Speaker 1>extremely sensitive amplifier and still makes sense of the faint

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<v Speaker 1>signals it receives. Then, when the Earth antenna transmits back

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<v Speaker 1>to the spacecraft, it uses extremely high power tens of

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<v Speaker 1>thousands of watts to make sure the spacecraft gets the

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<v Speaker 1>message for moral this and thousands of other topics because

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