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The trouble with radio waves is their invisibility. Rockets and spacesuits dominate the imagination. But human spaceflight -- let alone TV images of men walking on the moon -- would never have been possible without radio's invisible threads of information connecting the spacecraft to home.

In 1929, Richard E. Byrd made history -- not for reaching the South Pole, but for bringing on his Antarctic expedition 24 radio transmitters, 31 receivers, five radio engineers, three airplanes and an aerial camera. Unlike Ernest Shackleton's trans-Antarctic expedition, who 15 years earlier spent 17 months fighting for their lives after being trapped in the polar ice, Byrd's team was able to stay in constant communication with each other and with the outside world. It was the beginning of modern technology-aided exploration, and arguably the model for human spaceflight.

At midcentury, it wasn't clear that radio waves could pass beyond the earth's upper atmosphere. All we knew was that some of the shorter waves didn't get reflected back. In February 1945, Royal Air Force radar technician and aspiring science-fiction author Arthur C. Clarke, acting on behalf of the British Interplanetary Society, wrote a letter to the hobbyist magazine Wireless World noting that the German V2 rocket could be launched into the ionosphere and send measurements back to Earth. More powerful rockets still could launch what Clarke called "artificial satellites" into permanent geosynchronous orbit. "Three repeater stations, 120 degrees apart in the correct orbit," Clarke mused, "could give television and microwave coverage to the entire planet," a proposition he detailed at length in a full article that October.

How extraterrestrials phone home?  I think that's a rather presumptuous title, given that we have never met (officially, that is) any extraterrestrials. That's how WE "phone home."  But it may not be how extraterrestrials do it. To read the rest of the article, click here.
Category: Science