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Message: <blockquote data-quote="Umbran" data-source="post: 6116967" data-attributes="member: 177">As well you should, seeing as a transmitter on top of a 100 foot tower has a direct line of sight to receivers perhaps 12 miles away - beyond that you're reaching over the horizon, and then you're talking about transmitting through rock, refracting through, or reflecting off the atmosphere, which gets kind of iffy.  Power isn't the largest issue there.The first antenna used to detect radio from an astronomical source was built in 1931.  The first parabolic dish radio telescope was built in 1937.  I don't see any reason to think we needed to wait for Voyager-era technology.  The Voyager probes didn't have much power (470 Watts when launched), and needed to be received from much farther away than mere Mars.  Land-based transmitters have *lots* more power to work with.</blockquote>