Most T.V. channels straddle the 54-890 MHz (megahertz) frequency band. But even as technology changes, and more closed circuit-type T.V. transmission methods are used en masse, it is likely that future video signals will still leak into space. But for our discussion, we're interested in those early broadcast analog T.V. signals-signals out there. Somewhere.
What would happen if terrestrial audio-and-visual signals, dating back to the Golden Age of Television, were detected by extraterrestrials on distant planets? Is such an idea possible? And what would extraterrestrials make of our earliest T.V. signals?
Even with today's digital television retooling efforts, television is disseminated widely by an old medium-radio transmission. Broadcast T.V., in its purest sense, is a form of radio; that is, radio with pictures. It may come as a surprise to discover that the first powerful broadcast T.V. signals leaving planet Earth were neither the shortwave experiments by pioneering sci-fi writer and experimenter Hugo Gernsback in New York in the 1920s nor the broadcasts of 1950s American T.V. shows. Instead, the first T.V. signals to leave the Earth originated in Nazi Germany.
Earth's earliest, far-ranging video signals were German propaganda broadcasts between the 1930s and mid 1940s. While its video propaganda plans never panned out, the socialist Nazi government had hoped to equip every German household with a free T.V. set. While the technology existed for German television by the mid 1930s, the cost of CRT (cathode-ray tube) manufacturing and the infant medium's transmission infrastructure remained elusive. Hilter's opening remarks at the 1936 Berlin Olympic Games appear to qualify it as the first deep-space signal.
Radio astronomer Chris Davis, of Britain's Rutherford Appleton Laboratory, claims that terrestrial T.V.-radio signals like the Nazicasts of the '30s and '40s could be picked up on distant planets with the proper hardware and software.
"A good amount of Earth's artificial radiowaves, like the shortwave frequency variety, never get past the ionosphere," Davis said in a recent BBC interview. "However, modern broadcast television signals can pierce the atmosphere. These signals easily traverse space at the speed of light."
But as these signals cross interstellar medium, they would become very diffuse and difficult to focus at the receiving end.
"There are two things that you would need to get such a signal-firstly, it has to be able to leave our planet, secondly it would have to have as much power as possible," Davis noted. "As you go into space that power would dissipate. They would need more and more sensitive equipment to pick it up."
I'm sure that if advanced civilizations exist, they will have the ability to detect Earth's faintest television-radio signals. Of the question, what would aliens make of these signals, well, that's anybody's guess.
But, somewhere-out there-the television broadcasts of the Apollo 11 lunar landing, and original episodes of "Star Trek" and "The Brady Bunch" are approaching the recently discovered planetary system of Zeta Reticuli.
Farther out into space, the original broadcast signals of "The Lone Ranger" and "Howdy Doody" are approaching the planets orbiting Pi Mensae.
And reaching even farther into the vastness of the Milky Way, hypothetical extraterrestrials 73 light years distant may be watching humanity's first interstellar greeting-from none other than Adolph Hitler.
What's in the Sky: As we saw last week, many deep space objects congregate in Cassiopeia this month. The brighter ones are NGC 884, NGC 869, and Cr 33.
Lou Varricchio, M.Sc., is a former NASA science writer. He is a NASA-JPL Solar System Ambassador in Vermont and the 2009 recipient of U.S. Civil Air Patrol-USAF auxiliary's Maj. Gen. Chuck Yeager Aerospace Education Achievement Award.