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How Strong is the Signal from the Voyager 1 Spacecraft When it Reaches Earth?

-- | October 24, 2015

Question: What is the signal strength in watts received by the VLBA that is transmitted from Voyager 1? I recall that Voyager 1 transmits at 22 watts and is nearly 20 billion km away, so how weak is the signal here? — Robert

Answer: The answer to your question happens to be included in a story about the VLBA detecting Voyager 1 in 2014. As you said, the radio strength of Voyager 1 is about 23 watts. This signal is directed toward Earth, but since Voyager 1 is about 15 billion kilometers from Earth, by the time Voyager 1’s signal reaches us its power is less than an attowatt, or a billionth of a billionth of a watt.

Jeff Mangum

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